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Full text of "Insects, their ways and means of living" 5MITH$ONIAN
SCI ENTI FIC 8ERI ES
Editor-in-chie/
CHARLES GREELEY ABBOT, D.Se.
Secretary of the
Smithsonian Institution
Published by
S,I'ITHS©NIAN [NSTITUTI©N SER[ES.
N EW YOEE
THEIR
INSECTS
WAYS AND
OF LIVING
MEANS
ROBERT Ev.NS SNODGRASS
United States Bureau o Entomology
VOLUME FIVE
OF THE
SMITHSONIAN SCIENTIFIC SERIES
193o
COPYRIGHT 1930, BY
SMITHSONI/N INSTITUTION SERIES, Inc.
[Printed in the United States of America]
]lll rights rtsertd
Copyright Under the Articles of the Copyright Convention
of the Pan-American Republics and the
United States, August I I, 9o
CONTENTS
Il.
III.
IV.
V.
VI.
VII.
VIII.
IX..
X.
PREFACE
THE GRASSHOPPER
THE GRASSHOPPER'S COUSINS
ROACES AND OTHER ANCENT [NSECTS
WAYS AND MEANS OF LIVING
TERMITES
PLANT IICE
THE PERIODICAL CICADA
INSECT vIETAMORPHOSIS .
THE CATERPILLAR AND THE IOTH
MOSQUITOES AND FLIES
INDEX
i
26
77
99
25
52
i82
226
262
314
355
ILLUSTRATIONS
LIST OF PLATES
The Carolina Locust
. Miscellaneous insects
. The Green Apple Aphis
3- The Rosy Apple Aphis
4. The Apple-grain Aphis . .
. Nymph of the Periodical Cicada .
;. Newly emerged Cicada
7- Cicada laying eggs ........
8. Egg nests and eggs of the Periodical Cicada
9. Two species of large moths ......
o. The Cecropia Moth and the Polyphemus Moth
 . The Ribbed-cocoon Maker
IOE. The Peach-borer Moth
3- The Red-humped Caterpillar
4. The Tent Caterpillar
Fronttspiece
8
6o
7 o
92
98
212
OE6o
LIST OF TEXT FIGURES
i. Young grasshoppers ...... 2
OE. End structures of a grasshopper's body . 3
3- Grasshopper laying eggs ..... 4
4- Egg-pods of a grasshopper 5
ç. Eggs of a grasshopper ....... 6
. Young grasshopper emerging from the egg . 8
7- Eggs of a katydid ........ o
8. A young grasshopper ....... *OE
9- The growth stages of a grasshopper . 3
o. A parasitic fly ......... OEo
. Blister beetles ......... OEOE
IOE. A triungulin larva of a blister beetle OE3
13. Second-stage larva of a blister beetle OE4
I 4. Examples of Arthropoda .... OE7
 5. A "'singing'" grasshopper ..... OE9
I6. Another"singing" grasshopper 31
17. The feet of Orthoptera .......... 33
 8. Sound-making organs of a meadow grasshopper 34
19. Sound-making organs and ears of a conehead katydid 35
20. Auditory organ of a katydid ........ 37
2. A bush katydid ...... 38
22. The oblong-winged katydid 40
23. The angular-winged katydid . 4
24. The true katydid ..... 44
25. The katydid in various attitudes 45
26. Sound-making organs of the katydid" 48
27. A conehead katydid ..... 5o
28. The robust katydid . 5
29. The common meadow lat3did
3 o. The handsome meadow katydid . 53
3- The slender meadow katydid . 53
32. The Coulee cricket .... 55
33- Wings of a tree cricket 56
34- A mole cricket .... 57
35- The striped ground cricket 59
36. The common black cricket
37- The snowy tree cricket .... 64
38. Antennal marks of the tree crickets . 66
39- The narrow-winged tree cricket . 67
4o. A broad-winged tree cricket ...... 68
4- Back glands of a tree cricket ....... 68
42. The jumping bush cricket • - 7o
43- The common walking-stick insect
44. A gigantic walking-stick insect 7
45- A leaf insect ..... 73
46. The praying mantis 74
47- A shield-bearing manti 75
48. Egg case ofa mantis . . 75
49- Common household roaches 78
5o. Egg cases of roaches 79
5" Young of the Croton bg . 8
52. The house centipede 83
53- Wings of a cockroach . 84
54. A Paleozoic forest . 86
55- Fossil roaches . 90
56. Early fossil insects . 9 
57- Machilis ...... 93
58. Dragonflies . . 94
59- A young dragonfly . 96
60. A mayfly • • 97
61. A young mayfly ........ 98
6OE. The relation of the germ cells and body cells 1oo
63. External structure of an insect .....
64. Leg of a young grasshopper .........
65. Legs of a honeybee ........... o
66. Head and mouth parts of a grasshopper
67. Internal organs of a grasshopper .
68. Alimentary canal of a grasshopper
69. Heart of an insect ......
7 o. Respiratory system of a caterpillar
71. The brain of a grasshopper .
7 OE. Nervous system of a grasshopper
73- Reproductive organs of an insect
74- Ovipositor of a katydid
75- Termites .......
76. Termite work in a piece of wood ......
77. Worker and soldier castes and young of a termite
78. Heads of termite soldiers ........
79- Winged caste of a termite ......
8o. Short-winged reproductive caste of a termite
81. A wingless termite queen ......
8oE. Termite king and queen
83- Wing of an ordinary termite .
84. Wings of a Mastoterraes .....
85. Section of an underground termite nest .
86. Four types of termite nests .....
87. Large termite nest .....
88. Group of aphids feeding
89. How an aphis feeds ....
9 o. Section of the beak of an aphis
91. Aphis eggs ........
9 OE. Aphis eggs just belote hatching
93- Young aphis emerging from the egg .
94- Young aphids on apple buds ....
95- Young of three species of apple aphids .
96. Apple leaves infested by green apple aphis .
97- The green apple aphis .......
98. The rosy apple aphis on apple .
99- The rosy apple aphis on plantain
lOO. Maie and female of the rosy apple aphis
lol. Some common aphids of the garden .
lOoE. A ladybird beetle ......
1o3. The aphis-lion ....
lO4. The golden-eye, Chr.sopa .....
lO 5. Larva of a syrphus fly feeding on aphids
lO6. Adult syrphus flies .......
lO 7. A parasitized aphis
1o8. An aphis parasite, z¢phidius ........
lO 9. A female z¢phidius inserting an egg in a living aphis .
11o. Parasitized aphids on parasite cocoons ....
11t. A parasitized lady-beetle larva ......
llZ. A common cicada ..........
1o6
1o8
IO 9
l OEO
128
1.o
133
135
38
141
 46
147
149
 50
53
154
156
157
158
159
162
163
16ç
6
169
 7 °
173
174
176
176
77
178
178
78
179
8
183
! 13. Young nymph of the periodical cicada
114. Older nymph of the periodical cicada
I 15" Underground cells of the periodical cicada .
116. Fore leg of a cicada nymph ....
117. Cicada turrets .....
118. Transformation of tbe cicada .
119. Two forms of tbe periodical cicada
IoEO. Maie of tbe periodical cicada ....
loE!. Tbe bead and beak ofa cicada
1oEoE. Tbe sucking organ of a cicada
IoE 3. Section of a cicada's body
l oE 4. Sound-making organs of a cicada ....
1oE 5. Egg and newly-batcbed nymph of tbe cicada
1oE6. Young cicada nymph
IOE7- Motbs ofthe rail webworm . .
loE8. Tbe celery caterpillar and butterfly .
1oE9- Tbe Luna motb ......
13o. Lire of a cutworm
131. A maybeetle and its grub .
13oE- Lire stages of a lady-beetle
133. Lire stages of a wasp
!34. A dragonfly nymph ........
135. Various habitats of plant-feeding caterpillars
136. External structure of a caterpillar ....
137. Adult and larval forms of beetles
138. Diagram ofinsect metamorphosis
139. Springtails ..........
14o. A bristletail, Therrnobia ......
141. Tbe relation of a pupa to otber insect forms
147.. Muscle attachment on the body wall
143- Young tent caterpillars ......
!44- Eggs and newly-hatched tent caterpillars
145- First tent of young tent caterpillars .
146. Young tent caterpillars on a sbeet of silk
147. Mature tent caterpillars feeding ....
!48. Mature tent caterpillars ......
149- Twigs denuded by tent caterpillars
15o. A tent caterpillar jumping from a tree
15 l. Co£oon of a tent caterpillar
15 OE. Head of a tent caterpillar ....
153. Jaws ofa tent caterpillar . .
154- Internal organs of a caterpillar
155. Tbe spinning organs of a caterpillar . .
156. Tbe alimentary canal of a tent caterpillar .....
157. Crystals formed in tbe Malpigbian tubules .....
158. The fat-body of a caterpillar .........
l 9" Transformation of tbe tent caterpillar ......
186
187
I88
19o
I96
OE36
OE4 I
OE48
OE67
OE71
OE73
OE84
OE88
OE94
I60. Contents of the pupal blood
I6i. Moths of the tent caterpillar .
169.. Head of a tent caterpillar moth .
163. Head of a peach borer moth ....
164. Transformation of the alimentary canal
165. Reproductive organs of a female moth
166. Young tent caterpillars in the egg
167. A robber fly .......
168. Wings of insects
169 . The black horsefly . .
17o. Mouth parts of a horsefly .
171. Structure of a fly maggot .
179.. Rat-tailed maggots
173. Larva and pupa of a horsefly .
174. Life stages of a mosquito .
175. Structure of a mosquito larva
176. Mouth parts of a mosquito
177. A maie mosquito
178. Mosquito larvae
179. Mosquito pupae ....
18o. The female malaria mosquito . . .
181. Feeding positions of mosquito lavae
18oE. Life stages of the house fly ......
183. Head and mouth parts of the house fly .
184. Head of the stable fly .......
185. A tsetse fly ............
86. Head and mouth parts of the tsetse fly ....
3o3
3o7
3o8
3o8
31o
319.
313
316
317
33 °
334
335
337
339
34 °
341
344
346
347
349
INSECTS
THEIR WAYS AND MEANS
OF LIVING
PREFACE
IN the early days of zoology there were naturalists who
spent much time out of doors observing the ways of the
birds, the insects, and the other creatures of the fields and
woods. These men were hot steeped in technical learning.
Nature was a source of inspiration and a delight to them;
ber manifestations were to be taken fi»r granted and hot
questioned too closely. A mind able to accept appear-
ances for truth can express itself in the words of everyday
language--for language was invented long ago when
people did hot bother themselves much with facts- and
some of those early writers, inspired direct from nature,
bave left us a delightful literature based on their observa-
tions and reflections on the things of nature. The public
has liked to read the works of these men because they tell
of interesting things in an interesting way and in words
that can be understood.
At the saine time there was another class of nature
students who did hot care particu]arly what an animal did,
but who wanted to know how it was ruade. The devotees
of this cuit looked at things through microscopes; they
dissected ail kinds of creatures in order to learn their con-
struction and their structura] relationships. But they
round many t]aings on the inside of animais that had never
been named, so for these things they invented names; and
when their books were printed the public could hot read
them because of the strange words they contained. More-
over, since nature does hot usually embellish ber hidden
works, the anatomists could hot enhance their writings
with descriptive metaphors in the way the outdoor
naturalists could. Consequently, the students of struc-
ture bave never corne into favor with the reading public,
and their works are denounced as dry and tedious.
Iii
PREFACE
Then there arose still another group of inquiring minds.
Members of this school could hOt see anything worth while
in knowing merely either what an animal did or how it was
ruade. They devoted their efforts to discovering the
secrets of its workings. They invented instruments for
measuring the power of its muscles, for testing the nature
of the force that resides in its nerves; they ruade analyses
of its food and its tissues; they devised ail kinds of experi-
ments for revealing the causes of its behavior. The work-
ers in this branch, the physiologists, had to have a con-
siderable grounding in physics ànd chemistry; conse-
quently they came to write more or less in the languages
of those sciences and to express themselves in chemicai and
mathematical formulae. Their writings are hard for the
public to understand. Their statements, moreover, are
often at odds with preconceivedideas, since precon-
ceived ideas are conceived in ignorance, and the public at
large does hot take to this sort of thing--it cherishes above
ail its inherited opinions.
Therefore the old-time naturalist is still venerated, as
he deserves to be, and those who call themselves "nature
loyers" stili like to decry the iaboratory worker as an evil
being who would take the beauty from nature and destroy
the soul of man. A modern writer of the old schooi may
sell his wares, but when something goes wrong with his
stomach or his nerves, or when his plants or his animais
are attacked by disease, itis the knowledge of the labora-
torv scientist that cornes to his aid.
"J'he reason that the specific truths of nature must be
round out in laboratories is that there are too many things
mixed together in the fields. The laboratory naturalist
endeavors to untangle the confusion of elements in the
outdoor environment and to isolate the different factors
that affect the lire and behavior of an animal, in order
that he may be sure with just what he is dealing in his ef-
forts to determine the value of each one separately. By
creating a set of artificial environments in each of which
Iii]
PREFACE
only one natural factor is allowed to be operative at the
saine time, he is in a position to observe correctly, after
repeated experiments, just what effects proceed from this
cause and what from that.
Nature study, in the superficial sense, may be enter-
taining. We of the present age, however, must learn to
take a deeper insight into the lires of the other living
things about us. Insects, for example, are not curiosities;
they are creatures in common with ourselves bound by
the laws of the physical universe, which laws decree that
everything alive must live by observing the saine ele-
mental principles that make lire possible. t is only in
the ways and means by which we comply with the condi-
tions laid down by physical nature that we differ.
Many sincere people find it diflcult to believe in evolu-
tion. Their difficulty arises largely from the fact that
they look to the differences in structure between the
diverse types of living things and do not see the unity in
function that underlies ail physical forms of lire. Conse-
quently they do not understand that evolution means the
progressive structural divergence of the various lire forms
from one another, resulting from the different ways that
each has adopted and perfected for accomplishing the
saine ends. Man and the insects represent the extremi-
ties of two most divergent lines of animal evolution, and
by reason of the very disparity in structure between us the
bond of unity in function becomes ail the more apparent.
A study of insects, therefore, will help us the better to
understand ourselves in so far as it helps us to grasp the
fundamental principles of lire.
Some writers seem to think that the sole purpose of
writing is that it shall be read. Just as reasonable would
it be to claire that the only purpose of food is that
it shall be eaten. In the following chapters the reader
is offered an entomological menu in which the consider-
ation of nutrient value and the requirements of a balanced
meal have been given first attention. As a concession to
[iii l
PREFACE
palatability, however, as much as possible of the dis-
tastefil matter of technical terminology bas been ex-
tracted, and an attempt bas been ruade to avoid the pure
scientific style of literary cuisine, which forbids the use of
ail those ingredients whose object is that of inflation but
which, if properly admixed, will greatly aid in the process
of digestion.
Much of the material in several chapters is taken from
articles already printed in the ltnnttal Reports of the
Smithsonian Institution. The original drawings of most
of the color plates and line cuts are the property of the
United States Bureau of Entomology, though some of
them are here published for the first time.
R. E. S.
[ivl
INSECTS
THEIR WAYS AND MEANS OF I.IVING
CHAPTER I
THE GRASSHOPPER
SOMETIIVlE in spring, earlier or later according to the lati-
tude or the season, the fields, the lawns, the gardens, sud-
denly are teeming with young grasshoppers. Comical little
fellows are they, with big heads, no wings, and strong hind
legs (Fig. J. Thev feed on the fresh herbage and hop
lightly here and there, as if their existence in no way in-
volved the mystery of lire nor raised any questions as to
why they are here, how they came to be here, and whence
they came. Of these questions, the last is the only one
to which at present we can give a definite answer.
If we should search the ground closely at this season,
it might be possible to see that the infant and apparently
motherless grasshoppers are delivered into the visible
world from the earth itself. D,'ith this information, a
nature student of ancient times would have been satisfied
--grasshoppers, he would then announce, are bred spon-
taneously from marrer in the earth; the public would
believe him, and thereafter would countenance no con-
trary opinion. There came a rime in history, however,
when some naturalist succeeded in overthrowing this idea
and established in its place the dictum that every life cornes
from an egg. This being still our creed, we must look for
the grasshopper's egg.
[i]
INSECTS
The entomologist who plans to investigate the lives of
grasshoppers finds it easier to begin his studies the year
belote; instead of sifting the earth to find the eggs from
which the young insects are hatched in the swing, he ob-
serves the mature insects in the rail and secures a supply of
eggs freshly laid bv the females, either in the field or in
cages properly equiiped for them. In the laboratory then
Fro. . Young grasshoppers
he can closely watch the hatching and observe with ac-
curacy the details of the emergence. So, let us reverse the
calendar and take note of what the mature grasshoppers of
last season's crop are doing in August and September.
First, however, itis necessary to know just what insect
is a grasshopper, or what insect we designate by the naine;
for, unfortunately, names do hot always signify the saine
thing in different countries, nor is the saine naine always
applied to the saine thing in different parts of the saine
country. It happens to be thus with the terre "grass-
hopper." In most other countries they call grasshoppers
"locusts," or rather, the truth is that we in the United
States call locusts "grasshoppers," for we must, of course,
concede priority to Old World usage. When you read of
a "plague of locusts," therefore, you must understand
"grasshoppers." But a swarm of"seventeen-year locusts"
means quite another insect, neither locust nor grasshopper
--correctly, a cicada. Ail this mix-up of names and mal.ay
other misfits in out popular natural history parlance we
THE GRASSHOPPER
can blame probably on the earlv settlers ofour States, who
bestowed upon the creatures encountered in the New
World the names of animals familiar at home; but, having
no zoologists along for their guidance, thev ruade many
errors of identification. Scientists have sought to estab-
lish a better state of nomenclatural affairs by creating a
set of international names for all living things, but since
their names are in I.atin,
or I.atinized Greek, thev
are seldom practicable
for everyday purposes.
Knowing now that a
grasshopper is a locust,
it onlv needs to be
said that a true locust
is any grasshopperlike
insect with short horns,
or antelnae (see b'ron-
tispiece). A similar in-
sect with long slender
antennae s either a
katydid (Figs. 23, 24),
or a member of
the
cricket family (Fig. 39)-
If you will collect and
examine a few specimens
of locusts, which we will
proceed to call grass-
hoppers, vou may ob-
serve that some bave
_'eov P
B
I;J;. 2. The end of the bod y of a maie and
a female grasshopper
"]'he body, or abdomen, of a maie (AI is
bluntly rounded; that of the fernale (1
bears two pairs of thick prongs, which
constitute the egg-lasing organ, or ovi-
posltor
the rear end of the body smoothly rounded and that others
have the body ending in four horny prongs. The second
kind are females IFig. 2 B); the others (A) are males and
may be disregarded for the present. It is one of the pro-
visions of nature that whatever any creature is compelled
by its instinct to do, for the doing of that thing it is pro-
vided with appropriate tools. Its tools, however, unless
INSECTS
it is a human animal, are alwavs parts of its body, or of its
jaws or its legs. The set of prongs at the end of the body
of the female grasshopper constitutes a digging tool, an
instrument by means of which the insect makes a hole in
the ground wherein she deposits ber eggs. Entomologists
call the organ an o'ipositor, or egg-placer. Figure 2 B
F1c. 3- .'i le)hale grasshopper in the position of depositing a pod of eggs in a
hole in the ground dug with ber ovipositor. (Drawn from a photograph in"
U. S. But. Ent.)
shows the general form of a grasshopper's ovipositor; the
prongs are short and thick, the points of the upper pair are
curved upward, those of the lower bent downward.
When the female grasshopper is ready to deposit a
batch of eggs, she selects a suitable spot, which is almost
any place in an open sunny field where ber ovipositor can
penetrate the soil, and there she inserts the tip of ber
organ with the prongs tightly closed. When the latter
are well withit the ground, they are probably spread
apart so as to compress the earth outward, for the dri]]ing
[41
THE GRASSHOPPER
process brings no detritus to the surface, and gradually
the end of the insect's body sinks deeper and deeper, until
a considerable length of it is buried in the ground (Fig. 3)-
Now ail is ready for the discharge of the eggs. The exit
duct from the tubes of the ovary, which are filled with
eggs already ripe, opens just below and between the bases
of the lower prongs of the ovipositor, so that, when the
upper and lower prongs are separated, the eggs escape
from the passage between them. While the eggs are
being placed in the bottom of the well, a frothv gluelike
substance from the body of
the insect is discharged
over them. This sub-
stance hardens about the
eggs as it dries, but not in
a solid mass, for its frothv
nature leaves it full fil
cavities, like a sponge, and
affords the eggs, and the
young grasshoppers when
they hatch, an abundance
of space for air. To the
outside of the covering
substance, while it is ffesh
and sticky, particles of
earth adhere and make a
finely granular coating
Fc. 4- Egg pods of a grasshopper, show-
ing various shapes: one opened exposing
the eggs within. (Much enlarged)
over the mass, which, when hardened, looks like a small
pod or capsule that has been molded into the shape of the
cavity containing it (Fig. 4)- The number of eggs within
each pod varies greatly, some pods coritaining only hall
a dozen eggs, and others as many as one hundred and
fifty. Each female also deposits several batches of eggs,
each lot in a separate burrow and pod, before ber egg
supply is exhausted. Some species arrange the eggs
regularly in the pods, while others cram them in hap-
hazard.
INSECTS
The egg of a grasshopper is elongate-oval in shape
I Fig. 5), those of ordinary-sized grasshoppers being about
rhree-sixteenths of an inch in lengrh, or a little longer.
The ends of the
 eggs are rounded
or bluntly
pointed, and the
Iower extremity
(the egg being
generally placed
on end) appears
to have a small
cap over it. One
side of the egg is
always more
J .... curved than the
IFm. ç. Eggsofagrasshopper;onesplitattheupper opposite side,
end, howing the young grasshopper about to emerge which may be al-
most straight.
The surface is smooth and lustrous to the naked eye, but
under the microscope it is seen to be marked off by slightly
raised lines into many small polygonal areas.
Within each egg is the germ that is to produce a new
grasshopper. This germ, the living matter of the egg, is
but a minute fraction of the entire egg contents, for the
bulk of the latter consists of a nutrient substance, called
yolk, the purpose of which is to nourish the embryo as it
develops. The tiny germ contains in some form, that even
the strongest microscope will hot reveal, the properties
which will determine every detail of structure in the future
grasshopper, except such as may be caused by external cir-
cumstances. It would be highly interesting to follow the
course of the development of the embryo insect within the
egg, and most of the important facts about it are known;
but the story would be entirelv too long to be given here,
though a few things about the grasshopper's development
should be noted.
[61
THE GRASSHOPPER
The egg germ begins its development as soon as the eggs
are laid in the fall. In temperate or northern latitudes,
however, low temperatures soon intervene, and develop-
ment is thereby checked until the return of warmth in the
spring--or until some entomologist takes the eggs into an
artificially heated laboratory. The eggs ofsome species of
grasshoppers, if brought indoors before the advent of
freezing weather and kept in a warm place, will proceed
with their development, and young grasshoppers will
emerge from them in about six weeks. On the other hand,
the eggs of certain species, when thus treated, will hot
hatch at ail; the embryos within them reach a certain
stage of development and there they stop, and most of
them never will resume their growth unless they are sub-
jected to a freezing temperature! But, after a thorough
chilling, the young grasshoppers will corne out, even in
January, if the eggs are then transferred to a warm place.
To refuse to complete its development until frozen and
then warmed seems like a preposterous bit of inconsistency
on the part of an insect embryo; but the embryos ofmany
kinds of insects besides the grasshopper bave this saine
habit from which they will hot depart, and so we must con-
clude that itis hot a whim but a useful physiological prop-
erty with which they are endowed. The special deity of
nature delegated to look after living creatures knows well
that Boreas sometimes oversleeps and that an egg laid in
the fall, if it depended entirely on warmth for its develop-
ment, might hatch that saine season if mild weather should
continue. And then, what chance would the poor fledgling
have when a delayed winter cornes upon it? None at ail,
of course, and the whole scheme for perpetuation of the
species would be tlpset. But, if it is so arranged.that
development within the egg can reach completion only
after the chilling effect of freezing weather, the emergence
of the young insect will be deferred until the return of
warmth in the spring, and thus the species will bave a
guarantee that its members will hot be cut down by unsea-
[71
INSECTS
sonable hatching. There are, however, species hOt thus in-
sured, and these do sufier losses from rail hatching every
time winter makes a late arrival. Eggs laid in the spring
are designed to hatch the saine season, and the eggs of
species that lire in warm climates never require freezing
for their development.
The tough shell of the grasshopper's
 egg is composed of two distinct coats, an
outer, thicker, opaque one of a pale
brown color, and an inner one which is
thin and transparent. Just before hatch-
 ing, the outer coat splits open in an ir-
regular break over the upper end of the
egg, and usually half or two-thirds of the
way down the fiat side. This outer coat
can easily be removed artificially, and
 the inner coat then appears as a glisten-
, ing capsule, through the semitransparent
walls of which the little grasshopper in-
side can be seen, its members all tightly
folded beneath its body. When the
hatching takes place normally, however,
both layers of the eggshell are split, and
v,,. 6. Vou,g grss- the young grasshopper emerges by slowly
hopper emerging from
its eggshell making its way out of the cleft (Fig. 6).
Newly-hatched grasshoppers that have
corne out of eggs which some meddlesome investigator has
removed from their pods for observation very soon proceed
to shed an outer skin from their bodies. This skin, which is
already loosened at the rime of hatching, appears now as a
rather tightly fitting garment that cramps the sort legs and
feet ofthe delicate creature within it. The latter, however,
after a few forward heaves of the body, accompanied by
expansions of two swellings on the back of the neck (Fig.
6), succeeds in splitting the skin over the neck and the
back of the head, and the pellicle then rapidly shrinks and
slides down over the body. The insect, thus first exposed,
[81
THE GRASSHOPPER
liberates itself frorn the shriveled rernnant of its hatching
skin, and becornes a free new creature in the world. Being
a grasshopper, it proceeds to jurnp, and with its first ef-
forts clears a distance of four or rive inches, sornething like
fifteen or twenty tirnes the length of its own body.
When the young locusts hatch under normal undisturbed
conditions, however, we rnust picture them as coming out
of the eggs into the cavernous spaces of the egg pod, and
ail buried in the earth. They are by no rneans yet free
creatures, and they can gain their liberty only by burrow-
ing upward until they corne out at the surface of the
ground. Of course, they are hot very far beneath the sur-
face, and rnost of the way will be through the easily pene-
trated walls of the cells of the egg covering. But above the
latter is a thin layer of soli which rnay be hard-packed
after the winter's rains, and breaking through this layer
can hot ordinarily be an easy task. Not many entomolo-
gists have closely watched the newly-hatched grasshopper
ernerge from the earth, but Fabre has studied thern under
artificial conditions, covered with soli in a glass tube. He
relis of the arduous efforts the tiny creatures rnake, press-
ing their delicate bodies upward through the earth by
rneans of their straightened hind legs, while the vesicles on
the back of the neck alternately contract and expand to
widen the passage above. Ail this, Fabre says, is done
before the hatching skin is shed, and it is only after the
surface is reached and the insect has attained the ffeedom
of the upper world that the inclosing membrane is cast off
and the limbs are unencurnbered.
The things that insects do and the ways in which they do
thern are always interesting as mere facts, but how much
wiser might we be if we could discover why they do them!
Consider the young locust buried in the earth, for example,
scarcely yet more than an embryo. How does it know
that it is hot destined to live here in this dark cavitv in
which it first finds itself? What force activates the mech-
anism that propels it through the earth? And finally,
I9]
INSECTS
 7
what tells the creature that liberty is to be found above,
and hOt horizontally or downward? Many people believe
that these questions are hOt to be answered by human
knowledge, but the scientist has faith in the ultimate solu-
tion of ail problems, at least in terres of the elemental
forces that control the activities of the universe.
We know that ail the activities of animais depend upon
the nervous system, within which a form of energy resides
that is delicately responsive to external influences. Any
kind of energy harnessed to a physical mechanism will
produce results depending on the con-
struction of the mechanism. So the ef-
fects of the nerve force within a living
animal are determined by the physical
structure of the animal. An instinctive
action, then, is the expression of nerve
energy working in a particular kind of
machine. It would involve a digression
too long to explain here the modern con-
ception of the nature of instinct; it is
sufficient to say that something in the
surroundings encountered by the newly-
hatched grasshopper, or some substance
generated within it, sers its nerve energy
into action, that the nerve energy work-
ing on a definite mechanism produces the
motions of the insect, and that the
mechanism is of such a nature that it
FI6. 7- Eggs of a
pecies of katydid at- works against the pull ofgravity. Hence
tached to a twig; the the creature, if normal and healthy in ail
young insect in suc-
cessivestagesofernerg- respects, and if the obstacles are hOt too
ing from an egg; and great, arrives at the surface of the ground
the newly-hatched
young as inevitably as a submerged cork cornes
to the surface of the water. Some
readers will object that an idea like this destroys the
romance of lire, but whoever wants romance must go to
the fiction writers; and even romance is hot good fiction
[
THE GRASSHOPPER
unless it represents an effort to portray some truth.
lnsects hatched from eggs laid in the open may begin life
under conditions a little easier than those imposed upon
the young grasshopper. Here, for example (Fig. 7), are
some eggs of insects belonging to the katydid family.
They look like fiat oval seeds stuck in overlapping rows,
some on a twig, others along the edge of a leaf. When
about to hatch, each egg splits halfway down one edge and
crosswise on the exposed fiat surface, allowing a flap to
open on thls side, which gives an easy exit to the young
insect about to emerge. The latter is inclosed in a delicate
transparent sheath, within which its long legs and an-
tennae are closely doubled up beneath the body; but when
the egg breaks open, the sheath splits also, and as the
young insect emerges it sheds the skin and leaves it within
the shell. The new creature bas nothing to do now but to
stretch its long legs, upon which it walks away, and, if
given suitable food, it will soon be contentedly feeding.
l.et us now take closer notice of the little grasshoppers
(Fig. 8) that have just corne into the great world from the
dark subterranean chambers of their egg-pods. Such an
inordinatelv large head surely, you would say, must over-
balance the short tapering body, though supported on
three pairs of legs. But, whatever the proportions, nature's
works never have the appearance of being out of drawing;
because of some law of recompense, they never give you
the uneasy feeling of an error in construction. In spite of
its enormous head, the grasshopper infant is an agile crea-
ture. lts six legs are ail attached to the part of the bodv
immediately behind the head, which is known as the
thorax (Fig. 63, Th), and the rest of the body, called the
abdomen (,lb), projects free without support. .n insect,
according to its name, is a creature divided into parts,
"insect" means ïn-cut." A fly or a wasp, therefore, cornes
closer to being the ideal insect; but, while l,ot literally in-
sectcd between the thorax and abdomen, the grasshopper,
like the tir and the wasp and ail othcr insects, consists of a
[ll]
INSECTS
head, a thorax bearing the legs, and a terminal abdomen
(Fig. 63). On the head is located a pair of long, slender
antennae (Int) and a pair of large eyes (E). Winged in-
sects bave usually two pairs of wings attached to the back
of the thorax (II, II).
The outside of the insect's body, instead of presenting a
continuous surface like that of most animais, shows many
encircling rings where the hard integument appears to be
infolded, as it really is, dividing each body region except
the head into a series of short overlapping sections. These
body sections are called
Fç. 8. A young grasshopper, or nymph,
in the second stage after hatching
segments, and ail insects
and their relatives, in-
cluding the centipedes,
the shrimps, lobsters, and
crabs, and the scorpions
and spiders, are seg-
mented animais. Thein-
sect's thorax consists of
three segments, the first
of which carries the first
pair of legs, the second
the middle pair of legs, and the third the hind pair of legs.
The abdomen usually consists of ten or eleven segments,
but generally has no appendages, except a pair of small
peglike organs at the end known as the cerci, and, in the
adult female, the prongs of the ovipositor (Fig. 2 .B), which
belong to the eighth and ninth segments.
The head, besides carrying the antennae (Fig. 63,/lnt),
has three pairs of appendages grouped about the mouth,
which serve as feeding organs and are known collectively
as the mouth parts. The presence of four pairs of append-
ages on the head raises the question, then, as to why the
head is hot segmented like the thorax and the abdomen.
At an early stage of embryonic growth the head is seg-
mented, and each pair of its appendages is borne by a
single segment, but the head segments are later condensed
[2]
THE GRASSHOPPER
into the solid capsule of the cranium. Thus we see that
the entire body of an insect is composed of a series of seg-
ments which have become grouped into the three body
regions. Note that the insect does hot have a
"nose" or any breathing apertures on its head.
It has, however, many nostrils, called spirades
(Fig. 7 o, Sp), distributed along each side of
the thorax and the abdomen, lts breathing
system is quite different from ours, but will
be described in another chapter treating of
the internal organization (page  4)-
Most young insects grow rapidly be-
cause they must compress their entire
lives within the limits of a
single season. Generally a few
weeks suffice for them to reach
maturity, or at least the ma-
ture growth of the form in
which they leave the egg, for,
as we shall see, many in-
sects complicate their lires
by having several different
stages, in each of which
they present quite a dif-
ferent form. The grass-
hopper, however, is an in-
sect that grows by
a direct course from
its form at hatch-
ing to that of the
adult, and at ail
stages it is recog-
nizable as a grass-
hopper (Fig. 9)- A
young moth, on
the other hand,
hatching in the
FIG. 9- The metamorphosis of a grasshopper,
Melanoplus atlanus, showing its six stages of develop-
ment from the newly-hatched nymph to the fully-
winged adult. (Twice natural size)
INSECTS
form of a caterpillar, bas no resemblance toits parent, and
the saine is true of a young fly, which is a maggot, and of
the grublike young of a bee. The changes of form that
insects undergo during their growth are known as meta-
rnorphosis. There are different degrees of such trans-
formation; the grasshopper and its relatives bave a simple
metamorphosis.
An insect differs from a vertebrate animal in that its
muscles are attached to its skin. Most species of insects
bave the skin hardened by the formation of a strong out-
side c««tic««la to give a firm support to the muscles and to
reslst their pull. This function of the cuticula, however,
imposes a condition of permanency on it after it is once
formed. As a consequence the growing insect is con-
fronted with the alternatives, after reaching a certain
size, of being cramped to death within its own skin, or of
discarding the old covering and getting a new and larger
one. It bas adopted the course of expedlency, and peri-
odically molts. Thus it cornes about that the lire of an
insect progresses by stages separated by the molts, or the
shedding of the cuticula.
The grasshopper makes six molts between the time of
hatching and its attainment of the final adult form, a
period of about six weeks, and goes through six post-
embryonic stages (Fig. 9)- The first molt is the shedding
of the embryonic skin, which, we have seen, takes place
normally as soon as the young insect emerges from the
earth. The grasshopper now lires uneventfully for about
a week, feeding by preference on young clover leaves, but
taking almost any green thing at hand. During this time
its abdomen lengthens by the extension of the membranes
between its segments, but the hard parts of the body do
hot change either in slze or in shape. At the end ofseven
«r eight days, the insect ceases its activities and remains
quiet for a while until the cuticula opens in a lengthwise
sp[it over the back of the thorax and on the top of the
hcad. "l'he dead skin is then cast off, or rather, the grass-
THE GRASSHOPPER
hopper emerges from it, carefully pulling its legs and an-
tennae from their containing sheaths. The whole process
consumes only a few minutes. The emerged grasshopper
is now entering its third stage after hatching, but the shed-
ding of the hatching skin is usually not counted in the
series of molts, and the first subsequent molt, then, we will
say, ushers it into its second stage of aboveground life.
In this state the insect is different in some respects from
what it was in the first stage: it is hOt onlv larger, but the
body is longer in proportion to the size of'the head, as are
also the antennae, and particularly the hind legs. Again
the insect becomes active and pursues its routine life for
another week; then it undergoes a second molting, ac-
companied by changes in form and proportions that make
it a little more like a mature grasshopper. After shedding
its cuticula on three succeeding occasions, it appears in the
adult form, which it will retain throughout the remainder
of its life.
The grasshopper developed its legs, its antennae, and
most of its other organs while it was in the egg. It was
hatched, however, without wings, and yet, as everyone
knows, most full-grown grasshoppers have two pairs of
wings (Fig. 63, kk',/4/'3), one pair attached to the back of
the middle segment of the thorax, the other to the third
segment. It has acquired its wings, therefore, during its
growth from youth to maturity, and by examining the
msect in its different stages (Fig. 9), we may learn some-
thing of how the wings are developed. In the first stage,
evidence of the coming wings is scarcely apparent, but in
the second, the lower hind angles of the plates covering the
back of the second and third thoracic segments are a little
enlarged and project very slightly as a pair of lobes. In
the third stage, the lobes have increased in size and may
now be suspected of being rudiments of the wings, which,
indeed, they are. At the next molt, when the insect
enters its fourth stage, the little wing pads are turned
upward and laid over the back, which disposition hot only
I N S ECTS
reverses the natural position of the wings, but brings the
hind pair outside the front pair. At the next molt, the
wings retain their reversed positions, but they are once
more increased in size, though they still remain far short
of the dimensions of the wings of an adult grasshopper.
At the time of the last molt, the grasshopper takes a
position with its head downward on some stem or twig,
which it grasps securely with the claws of its feet. Then,
when its cuticula splits, it crawls downward out of the
skin. Once free, however, it reverses its position, and the
wisdom of this act is seen on observing the rapidly expand-
ing and lengthening wings, which can now bang down-
ward and spread out freely without danger of crumpling.
In a quarter of an hour the wings have enlarged from small,
insignificant pads to long, rhin, membranous fans that
reach to the tip of the body. This rapid growth is ex-
plained by the fact that the wings are hollow sacs; their
visible increase in size is a mere distention of their wrinkled
walls, for they were fully formed beneath the old cuticula
and lay there before the molt as little crumpled wads,
which, when released by the removal of the cases that
cramped them, rapidly spread out to their full dimensions.
"Fheir rhin, soft walls then corne together, dry, and harden,
and the limp, flabby bags are converted into organs of
flight.
t is important to understand the process of molting as
it takes place in the grasshopper, because the processes of
metamorphosis, such as those which accomplish the trans-
formation of a caterpillar into a butterfly, differ only in
degree from those that accompany the shedding of the
skin between any two stages of the grasshopper's life. The
principal growth of the insect is ruade during those resting
periods preceding the molts. It is then that the various
parts enlarge and make whatever alterations in shape they
are to bave. "l'he old cuticula is already loosened and the
changes go on beneath it, while at the saine time a new
cuticula is generated over the remodeled surfaces. The
l'61
THE GRASSHOPPER
increased size of the antennae, legs, and wings causes them
to be compressed in the narrow space between the new and
the old cuticula, and, when the latter is cast off, the
crumpled appendages expand to their full size. The ob-
server then gets the impression that he is witnessing a sud-
den transformation. The impression, however, is a false
one; what is really going on is comparable with the display
of new dresses and coats that the merchant puts into his
show windows at the proper season for their use, which he
has just unpacked from their cases but which were pro-
duced in the factories long before.
The adult grasshoppers lead prosaic lires, but, like a
great many good people, they fill the places allotted to
them in the world, and see toit that there will be other
occupants of their own kind for these saine places when
they themselves are forced to vacate. If they seldom tir
high, it is because it is hot the nature of locusts to do so;
and if, in the East, one does sometimes soar above his
fellows, he accomplishes nothing, unless he happens to
land on the upper regions of a Manhattan skyscraper,
when he may attain the glory of a newspaper mention of
his exploit--most likely, though, with his naine spelled
wrong.
On the other hand, like ali common folk born to ob-
scurity and enduring impotency as individuals, the grass-
hopper in masses of his kind becomes a formidable creature.
Plagues of locusts are of historic renown in countries south
of the Mediterranean, and even in out own country hordes
of grasshoppers known as the Rocky Mountain locust did
such damage atone time in the States of the Middle West
that the government sent out a commission of entomolo-
gists to investigate them. This was in the years following
the Civil V'ar, when, for some reason, the iocusts that
normaily inhabited the Northwest, east of the Rocky
Mountains, became dissatisfied with their usual breeding
grounds and migrated in great swarms into the States of
the Mississippi valley, where they brought destruction to
[7]
INSECTS
ail kinds of crops wherever they chanced to alight. In
the new localities thev. would lay their eggs, and the young
of the next season, after acquiring their wings, would
rnigrate back toward the region whence the parent swarrn
had corne the year belote.
The entornologists of the investigating commission in
the vear 877 tell us that on a favorable day the rnigrating
locu'ts "rise early in the forenoon, frorn eight to ten
o'clock, and settle down to eat frorn four to rive in the
afternoon. The rate at which they travel is variously
estirnated frorn three to fifteen or twenty mlles an hour,
deterrnined by the velocity of the wind. Thus, insects
which began to fly in Montana by the middle of July may
hot reach lklissouri until August or early September, a
period of about six weeks elapsing before they reach their
destined breeding grounds." The appearance of a swarrn
in the air was described as being like that of "a vast body
cf t']eecy clouds," or a "cloud of snowflakes," the rnass of
flying insects "often having a depth that reaches frorn
cornparatively near the ground to a height that baffles
rhe keenest eye to distinguish the insects in the upper
stratum." It was estirnated that the locusts could fly
at an elevation of two and a hall rniles from the general
surface of the ground, or 5,ooo feet above sea level. The
descending swarrn falls upon the country "like a plague
or a blight," said one of the entornologists of the com-
mission, Dr. C. V. Riley, who bas left us the following
graphic picture of the circumstances:
The fariner plows and plants. He cultivates in hope, watching his
growing grain in graceful, wave-like motion wafted to and fro by the
warm summer winds. The green begins to golden; the harvest is at
hand. Joy lightens his labor as the fruit of past toil is about to be
realized. The day breaks with a smiling sun that sends his ripening
rays through laden orchards and-promising fields. Kine and stock
of every sort are sleek with plenty, and ail the earth seems glad. The
day grows. Suddenlv the sun's'face is darkened, and clouds obscure
the skv. The joy o(the morn gives way to ominous fear. The day
closes, and ravenous Iocust-swarms have fallen upon the land. The
[18]
THE GRASSH(}PPER
morrow cornes, and, ah! what a change it brings! The fertile land of
promise and plenty bas hecome a desolate waste, and old Sol, even at
his hrightest, shines sadlv through an atm«»sphere alive with mvriads
«]f glittering insects.
Even today the farmers of the Middle Western States
are often hard put toit to harvest crops, especially alfalfa
and grasses, from fields that are teeming with hungry
grasshoppers. Bv two means, principally, they seek relief
from the devouring hordes. One method is that of driv-
ing across the fields a device known as a "hopperdozer,"
which collects the insects bodily and destroys them. The
dozer consists essentially of a long shallow pan, twelve or
fifteen feet in length, set on low runners and provided with
a high back ruade either of metal or of cloth stretched over
a wooden frame. The pan contains water with a rhin
film of kerosene «»ver it. As the dozer is driven over the
field, great numbers of the grasshoppers that fly up before it
either land directlv in the pan or fall into it after striking
the back, and the k-erosene film on the water does the test,
for kerosene even in very small quantity is fatal to the
insects. In this manner, many bushels of dead locusts
are taken often from each acre of an al/alfa field; but still
great num}ers of them escape, and the dozer naturally
can hot be used on rough or uneven ground, in pastures,
or in fields with standing crops. A more generally effec-
tive method of killing the pests is that of poisoning them.
A mixture is prepared of bran, arsenic, cheap molasses, and
water, suPficient]v moist to adhere in small ]umps, with
usually some substance added which is supposed to make
the "mash" more attractive to the insects. The deadlv
bait is then finelv broadcast over the infested fields.
While such methods of destruction are effective, thev
bear the crude and c(}mmonplac¢ stamp (}f human wavs.
See how the thing is done when insect contends agai:st
insect. A fly, hot an ordinarv fly, but one known to
entomologists as A'arcoph«,a ('«/lvi I I;ig. o), being
n:tmed after l}r. E. {I. G. Kclly,vho has given us a
INSECTS
description of its habits, frequents the fields in Kansas
where grasshoppers are abundant. Individuals of this
fly, according to Doctor Keily's account, are often seen
to dart af ter grass-
FIG. IO. A fly whose larvae are parasitic on grass-
hoppers, 8arcopaga kellyi. (Much enlarged)
hoppers on the
wing and strike
against them.
The stricken in-
sect at once drops
to the ground.
Examination re-
veals no physical
injury to the vic-
tire, but on a dose
inspection there
may be round ad-
hering to the tln-
der gurface of a
wing severai tiny, sofi, white bodies. Poison piiis?
Pellets of infection? Nothing so ordinary. The things
are alive, they creep along the foids of the wing toward
its base- they are, in short, young files born at the instant
the body of the mother fly struck the wing of the grass-
hopper. But a young fly wouid never be recognized as the
offspring ofits parent; it is a wormlike creature, or maggot,
having neither wings nor legs and capable of moving only
by extending and contracting its sort, flexible body (Fig.
 g'_ D).
In form, the young Sarcophaga kellvi does hot differ par-
ticu]ar]y from the maggots ofother kinds of flies, but the
.qarcophaga flies in general differ from most other insects
in that their eggs are hatched within the bodies of the
females, and these flies, therefore, give birth to young
maggots instead of iaying eggs. The female of Sarcophaga
kell),i, then, when she ]aunches ber attack on the flying
grasshopper, is munitioned with a ]oad of young maggots
readv to be discharged and stuck by the moisture of their
[ 20]
THE GRASSHOPPER
bodies to the object of contact. The young parasites thus
palmed off by their mother on the grasshopper, who has no
idea what has happened to him, make their way to the base
of the wing of their unwitting host, where thev find a ten-
der membranous area which thev penetrate and thereby
enter the body of the victim. 12lere they feed upon the
liquids or tissues of the now helpless insect and grow to
maturity in from ten to thirty days. Meanwhile, how-
ever, the grasshopper bas died; and when the parasites are
full grown, they leave the dead bodv and burv themselves
in the earth to a depth of from two to six inches. Here
they undergo the transformation that will give them the
form of their parents, and when thev attain this stage they
issue from the earth as adult winged files. Thus, one
insect is destroved that another may lire.
ls the .'arcophaga kellvi a creature of uncanny shrewd-
ness, an ingenious inventor of a novel way for avoiding the
work of caring for ber offspring? Certainly her method
is an improvement on that of leaving one's newborn prog-
eny on a stranger's doorstep, for the victim of the flv must
accept the responsibility thrust upon him whether "he will
or hot. But Doctor Kelly tells us that the flies do hot
know grasshoppers from other flying insects, such as
moths and butterflies, in which their maggots do hot find
congenial hosts and never reach maturity. Furthermore,
he says, the ardent tir mothers will go after pieces of
crumpled paper thrown into the wind and will discharge
their maggots upon them, to which the helpless in fan ts cling
without hope of survival. Such performances, and many
similar ones that could be recounted of other insects, show
that instinct is indeed blind and depends, hot upon fore-
sight, but on some mechanical action of the nervous sys-
rem, which gives the desired result in the majority of cases
but which is hot guarded against unusual conditions or
emergencies.
When we consider the manv perfected instincts among
insects, we are often shocked to find apparent cases of
[21]
INSECTS
flagrant neglect on the part of nature for her creatures,
where it would seem a remedy for their ills would be easy
to supply.
In human society of modern rimes the criminal element
bas corne to look no different from the law-abiding class of
citizens. Formerly, if we may judge from pictures and
stage representations, thieves and thugs were tough-look-
ing individuals that could hot be mistaken on sight, but
A
Ftt.. h Two blister beetles whose larvae feed on grasshopper
eggs. (Twice natural size)
A, Epicauta marginata. B, Eplauta :'ittata
today our bandits are spruce young tllows that pass with-
out suspicion in the crowd. And thus it is with the in-
sects, ail unsuspectingly one may be rubbing elbows with
another that overnight will despoil his home, or that bas
already committed some act of violence against his neigh-
bot. Here, for example, in the saine field with the grass-
hoppers, is ara innocent-looking beetle, about three-
quarters of an inch in length, black and striped with yellow
(Fig. Il B). His entomological naine is Epicauta ,ittata,
which, of course, means nothing to a locust. He is now
a vegetarian, but in his younger days he ravished the nest
of a grasshopper and devoured the eggs, and his progeny
will do the same again. Epicauta and others of his family
THE GRASSHOPPER
are known as "blister beetles" because they have a sub-
stance in their blood, called cantharidin, famous for its
blistering properties and formerly much used in medicine.
The female blister beetles of several species lay their eggs
in the ground in regions frequented by grasshoppers, where
the young on hatching can find the egg-pods of the latter.
The little beetles (Fig. 1_) hatch in a form quite different
from that of their parents and are known as triungulins
hecause of two spines beside the single claw on each of
their feet, which gives the foot a three-clawed appearance.
Though the young scapegrace of a beetle is a housebreaker
and a thief, his story, like that of too many criminals,
unfortunately, makes interesting read-
ing, and the following account is taken,
with a few omissions, from the history
of Epicauta vittata as given bv Dr.
C. V. Riley:
From July till the middle of October the
eggs are being laid in the ground in loose, irreg-
ular masses of about 3 o on an average--the
female excavating a hole for the purpose, and
afterwards covering up the mass by scratching
with ber feet. She lays at several different
intervals, producing in the aggregate probably
from four to rive hundred ova. She prefers for
purposes of oviposition the very saine warm
sunny locations chosen by the locusts, and
doubtless instinctively places ner eggs near
those of these last, as I bave on several occa- Fw,. I. The first-
sions round them in close proximity. In the stage larva, or °°triun-
gulin,'" of the strlped
course of abo'ut fo days--more 6r less accord- blister beetle ¢fig. 
ing to the temperature of the grotlnd--the BI. Enlarged ltimes.
first larva or triungulin hatches. These little (From Riley)
triungulins (Fig. ioE), at first feeble ara per-
fectly white, soon assume their natt.ral light-br«»wn culor and commence
to more ahout. At night, or during cold or wct weather, ail tll«»Se
of a batch huddle together with littlc motion, but when warnlcd bv
the sun they become very active, running with thcir hmg legs over thc
ground, and prying with their large heads and strong jaws into everv
crease and crevice in the soli, into which, in dut. time, thcy hurrow
[231
INSECTS
and hide. As becomes a carnivorous creature whose prey must be
industriously sought, they display great powers of endurance, and
will survive for a fortnight without food in a moderate temperature.
Yet in the search for locust eggs many are, without doubt, doomed
to perish, and only the more fortunate succeed in finding appropriate
diet.
Reaching a locust egg-pod, out triungulin, by chance, or instinct,
or both combined, commences to burrow through the mucous neck,
or covering, and makes its first repast thereon. If it bas been long
in search, and its jaws are well hardened, it makes quick work through
this porous and :ellular marrer, and at once gnaws away at an egg,
first devouring a portion of the shell, and then, in the course of two
or three days, sucking up the contents. Should two or more triun-
gulins enter the saine egg-pod, a deadly conflict sooner or later ensues
until one alone remains the victorious possessor.
The surviving triungulin then attacks a second egg and
more or ]ess comp]ete]y exhausts its contents, when, after
about eight days from the time of its hatching, it ceases
from its feeding and enters a period of
rest. Soon the skin splits along the
back, and the creature issues in the
second stage of its existence. Very
curiously, it is now quite different in
appearance, being white and soft-bodied
and having much shorter legs than
before (Fig. 13). After feeding again on
the eggs for about a week, the creature
molrs a second time and appears in a
still different form. Then once more,
and yet a fourth time, it sheds its skin
and changes its form. Just before the
fourth molt, however, it quits the eggs
FI. 3- The second-
s,g h.-,., o« ,h¢ and burrows a short distance into the
striped blister beetle, soli, where it composes itself for a
(Frorn Riley)
period of retirement, and here undergoes
another mo]t, in which the skin is hot cast off. Thus the
half-grown insect passes the winter, and in spring molts a
sixth time and becomes active again, but hot for long- its
larval lire is now about to close, and with anoher molt
[4]
THE GRASSHOPPER
it changes to a pupa, the stage in which it is to be trans-
formed back into the form of its beetle parents. The final
change is accomplished in less than a week, and the
creature then emerges from the soli, now a fully-formed
striped blister beetle.
The grasshoppers' eggs furnish food for many other
insects besides the young blister beetles. There are species
of flies and of small wasplike insects whose larvae feed in
the egg-pods in much the saine manner as do the triungu-
lins, and there are still other species of general feeders
that devour the locust eggs as a part of their miscellaneous
diet. Notwithstanding ail this destruction of the germs
of their future progeny, however, the grasshoppers still
thrive in abundance, for grasshoppers, like most other
insects, put their trust in the admonition that there is
safety in numbers. So many eggs are produced and stored
away in the ground each season that the whole force of
their enemies combined can hot destroy them ail, and
enough are sure to corne through intact to render certain
the continuance of the species. Thus we see that nature
has various ways of accomplishing her ends--she might
have given the grasshopper eggs better protection in the
pods, but, being usually careless of individuals, she chose
to guarantee perpetuance with fertility.
[251
CHAPTER 1I
THE GRASSHOPPER'S COUSINS
N.TURE'S tendency is to produce groups rather than in-
dividuals. Any animal you can think of resembles in
sol.ne way another animal or a numnber of other animnals.
An insect resemnbles on the one hand a shrimnp or a crab,
and on the other a centipede or a spider. Resel.nblances
amnong animnals are either superficial or fundamnental. For
examnple, a whale or a porpoise resel.nbles a fish and lires
the lire of a fish, but has the skeleton and other organs of
land-inhabiting mnamnmnals. Therefore, notwithstanding
their formn and aquatic habits, whales and porpoises are
classed as mammnals and hot as fishes.
When resemnblances between animais are of a funda-
mental nature, we believe that they represent actual blood
relationships carried down frol.n sol'ne far-distant colmmon
ancestor; but the determination of relationships between
animnals is hot always an easy l'natter, because it is often
diflïcult to know what are fundal.nental characters and
what are superficial ones. It is a part of the work of
zoologists, however, to investigate closely the structure of
ail animnals and to establish their true relationships. The
ideas of relationship which the zoologist deduces frol.n his
studies of the structure of animais are expressed in his
classification of thel.n. The primnary divisions of the
Animal Kingdomn, which is generally likened to a tree, are
called branches, or loh_vla (singular, lohylum).
The insects, the centipedes, the spiders, and the shrimps,
crayfish, lobsters, crabs, and other such creatures belong to
the phylurn ,qrthrolooda. The naine of this phylumn means
[61
THE GRASSHOPPER'S COUSINS
"jointed-legs"; but, since many other animais have jointed
legs, the naine is hot distinctive, except in that the legs of
the arthropods are particularly jointed, each being com-
posed of a series of pieces that bend upon each other in
different directions. A naine, however, as evervbodv
knows, does hot have to mean anything, for Mr. mit[a
1:,. 4- Examples of fi»ur common classes of the Arthropoda
A,a crab /Crustacea). B,a spider (Arachnida). C, a centipede (Chilopoda).
1), a fly Ilnsecta, or Hexapoda)
mav be a carpentér, and Mr. Carpenter a smith. A phylum
is c]ivided into classes, a class into orders, an order into
/amilies, a family into genera (singular, genus), and a genus
is composed ofspecies (the singular of which is also species).
Species are hard to define, but they are what we ordinarily
regard as the individual kinds of animals. Species are
given double names, first the genus naine, and second a
specific naine. },'or example, species of a common grass-
hopper genus named :lelanoplus are distinguished as
,1 tela,«oplus atlanus, ,,l lelanoplus f emur-rubrum, l$1elanoplus
diflerentialis, etc.
[27]
INSECTS
The insects belong to the class of the Arthropoda known
as the Inse'ta, or t-Iexatoda. The word "insect," as we
have seen, means "in-cut," while "hexapod" means "six-
legged"--either term, then, doing very well for insects.
The centipedes (Fig. 4 C) are the ;$IyriaIoda , or many-
footed arthropods; the crabs (A), shrimps, lobsters, and
others of their kind are the Oustacea, so called because
most of them have hard shells; the spiders (B) are the
.grack,,ida, named after that ancient Greek maiden so
boastful of her spinning that Minerva turned her into a
spider; but some arachnids, such as the scorpion, do not
make webs.
The principal groups of insects are the orders. The
grasshopper and its relatives constitute an order; the
beetles are an order; the moths and butterflies are another
order; the flies another; the wasps, bees, and ants still
another. The grasshopper's order is called the Ortottera,
the word meaning "straight-wings," but, again, hot sig-
nificant in ail cases, though serving very well as a name.
The order is a group of related families, and, in the Or-
thoptera, the grasshoppers, or locusts, make one family,
the katydids another, the crickets a third; and ail these in-
sects, together with some others less familiar, may be said
to be the grasshopper's cousins.
The orthopteran families are notable in many ways,
some for the great size attained by their members, some
for their remarkable forms, and some for musical talent.
While this chapter will be devoted principally to the
cousins of the grasshopper, a few things of interest may
still be said about the grasshopper himself, in addition to
what was given in the preceding chapter.
THE GRASSHOPPER FaMLV
The family of the grasshoppers, or locusts, is the
Acrididae. Ail the members are much alike in form and
habits, though some have long wings and some short wings,
and mme reach the enormous size of nearly six inches in
PLATE 1
A group of insects representing rive common entomological Orders.
Figure 2 is a damselfly, a kind of dralonfly , from New Guinea, Order
Odonata; 4 is a grasshopper, and 6 a winged walking-stick of Japan,
representing two familles of Orthoptera;  and 8 are sucking bugs,
Order Hemiptera, which includes also the aphids and the cicadas:
3 is a wasp ri'oto Paragmy, and 7 a solitarv bee from Chile, Order
tlymenoptera; 5 is a two-winged tir of the Order Diptera, from Japan.
To entomologists these insects are known as follows: , Pm:vphes
laetus; OE, unidentified; 3, Pepsis completa; 4, Heliastus benjamini; 5,
Pantophthahnus vittatus; 6, 3licadina çhh«ctanoides; 7, Caupolicana
Fuk'icolli.,; 8, .llargasus afzeH
THE GRASSHOPPER'S COUSINS
iength. The front wings are long and narrow (Fig. 63,
H'_), somewhat stiff, and of a leathery texture. They are
laid over the thinner hind wings as a protection to the
latter when the wings are foided over the back, and for
this reason they are called the tegmina (singular, tegmen).
The hind wings, when spread (lI'), are seen to be large
fans, each with many ribs, or veins, springing from the
base. These wings are gliders rather than organs of flight.
For most grasshoppers leap into the air by means of
their strong hind legs and then saii off on the outspread
wings as far as a weak fluttering of the latter wili
carry them. One of our common species, however, the
Carolina Iocust (Frontispiece), is a strong flyer, and when
F. I 5. A grasshopper, Chloealtis conspersa, that rnakes a sound by scraping
its hind thighs over sharp-edged veins of its wings
A, the maie grasshopper, showing the sound-rnaking veins of the wing (b). B,
inner surface of right hind leg, showing row of teeth (a) on the fernur. C,
severa teeth of the fernur (enlargedJ
flushed flits away on an undulating course over the
weeds and bushes and sometimes over the tops of small
trees, but always swerving this wav and that as if unde-
cided where to alight. The great fl'ights of the migratory
locusts, described in the last chapter, are said to have been
accomplished more by the winds than bv the insects'
strength of wing.
The iocusts are distinguished by the possession of large
[zg]
INSECTS
organs on the sides of the body that appear to be designed
for purposes of hearing. No insect, of course, bas "ears"
on its head; the grasshopper's supposed hearing organs are
located on the base of the abdomen, one on each side
(Fig. 63, Tre). Each consists of an oval depression of the
body wall with a thin eardrumlike membrane, or tympa-
hum, stretched over it. Air sacs lie against the inner face
of the membrane, furnishing the equilibrium of air pressure
necessary for free vibration in response to sound waves,
and a complicated sensory apparatus is attached to its
inner wall. Even with such large ears, however, attempts
at making the grasshopper hear are never very succeasful;
but its tympanal organs bave the saine structure as those
of insects noted for their singing, which presumably,
therefore, can hear their own sound productions.
Not many of the grasshoppers are muscial. They are
mostly sedate creatures that conceal their sentiments, if
they bave any. They are awake in the daytime and they
sleep at night -commendable traits, but habits that seldom
beget much in the way of artistic attainment. Yet a few
of the grasshoppers make sounds that are perhaps music
in their own ears. One such is an unpretentious little
brown species (Fig. 15) about seven-eighths of an inch in
length, marked by a large black spot on each side of the
saddlelike shield that covers his back between the head and
the wings. He bas no other naine than his scientific oneof
Ckloealtis conspersa, for he is hot widely known, since his
music is of a very feeble sort. According to Scudder, his
only notes resemble tsikk-tsikk-tsikk, repeated ten or twelve
times in about three seconds in the sun, but at a slightly
lower rate in the shade. Chloealtis is a fiddler and plays
two instruments at once. The fiddles are his front wings,
and the bows his hind legs. On the inner surïace f each
hind thigh, or./e»mr, there is a row of minute teeth (Fig.
5 B, a), shown more magnified at C. When the thighs
are rulbed ()ver thc edges of the wings, their teeth scrape
,m a sharp-edged rein indicated bv b. This produces the
[3ol
THE GRASSHOPPER'S COUSINS
tsikk-sound just mentioned. Such notes contain little
music to us, but Scudder says he has seen three males sing-
ing to one female at the same time. This female, however,
B cu
\_.; C
F«. 16. .tf grasshopper, Mecostethus gracilis, that makes a sound
by scraping sharp ridges on the inner surfaces of its hind thighs
over toothed veins of the wings
A, the maie grasshopper. B, left front wing; the rasping rein is
the one marked I. C, a part of the rasping rein and its branches
more enlarged, showing rows of teeth
was.busy laying her eggs in a near-by stump, and there is
no evidence given to show that even she appreciated the
efforts of her serenaders.
Several other little grasshoppers fiddle after the manner
of Chloealtis; but another, Mecostethus gracilis by naine
(Fig. J6), instead of having the rasping points on the legs,
has on each ri)re wing one rein (B, I) and its branches pro-
vided with many small teeth, shown enlarged at C, upon
which it scrapes a sharp ridge situated on the inner sur-
face of the hind thigh.
In another group of grasshoppers there are certair
species that make a noise as they fly, a crackling sound
[3 t ]
INSECTS
apparently produced in some way by the wings themselves.
One of these, common through the Northern States, is
known as the cracker locust, Circotettix verruculatus, on
account of the loud snapping notes it emits. Several
other members of the saine genus are also cracklers, the
noisiest being a western species called C. carlingianus.
Scudder says he has had his attention drawn to this grass-
hopper "by its obstreperous crackle more than a quarter of
a toile away. In the arid parts of the West it has a
great fondness for rocky hillsides and the hot vicinity of
abrupt cliffs in the full exposure to the sun, where its
clattering rattle re-echoes from the walls."
TuE KATYDID ITAMIL¥
While the grasshoppers give examples of the more
primitive attempts of insects at musical production and
may be compared in this respect to the more primitive of
human faces, the katydids show the highest development
of the art attained by insects. But, just as the accom-
plishments of one member of a human family may give
prestige to ail his relations and descendants, so the talent
of one noted member of the katydid family bas given
notoriety to ail his congeners, and his justly deserved
naine has corne to be applied by the undiscriminating
public to a whole tribe of singers of lesser or very mediocre
talent whose only claire to the naine of katydid is that of
family relationship. In Europe the katydids are called
simply the longhorn grasshoppers. In entomology the
family is now the Tettigoniidae, though it had long been
known asthe Locustidae.
The katydids in general are most easily distinguished
from the locusts, or shorthorn grasshoppers, by the great
length of their antennae, those delicate, sensitive, tapering
threads projecting from the forehead. But the two fami-
lles differ also in the number of joints in their feet, the
grasshoppers having three (Fig. 17 A) and the katydids
four (B). The grasshoppers place the entire foot on the
[31
THE GRASSHOPPER'S COUSINS
ground, while the katydids ordinarily walk on the three
basal segments only, carrying the long terminal joint
elevated. The basal segments have pads on their under
sides that adhere to any smooth surface such as that of a
leaf, but the terminal joint bears a pair of claws used
when it is necessary to grasp the edge of a support. The
katydids are mostly creatures of the night and, though
usually plain green in color, many of them have elegant
forms. Their attitudes and general
comportment suggest much more re-
finement and a higher breeding than
that of the heavy-bodied locusts.
Though some members of the katydid
family live in the fields and are very
grasshopperlike or even cricketlike
in form and manners, the character-
istic species are seclusive inhabitants
of shrubbery or trees. These are the
true aristocrats of the Orthoptera.
An insect nmsician differs in many
respects from a human musician,
aside from that of being an insect in-
stead of a human being. The insect
artists are ail instrtlmentalists; but
since the poets and other,,ignorant
people alwavs speak of the singing"
of the crickêts and katydids, it will be
Fie.. 17. Distinctive char-
acters in the feet of the
three familles of singing
Orthoptera
A, hind foot of a grass-
hopper. B, hind foot of a
katydid. C, hind foot of
a cricket
easier to use the language of the public than to correct it,
especially since we have nothing better to offer than the
word stridldatbg, a l.atin derivative meaning "'to creak."
But words do hot matter if we explain what we mean by
them. It must be understood, therefore, that though we
speak of the "songs" of insects, insects do not have true
voices in the sense that "voice" is the production of sound
by the breath playing on vocal cords. Ail the musical
instruments of insects, it is true, are parts of their bodies;
but they are to be likened to fiddles or drums, since, for the
[331
INSECTS
production of sound, they depend upon rasping and vibrat-
mg surfaces. The rasping surfaces are usually, as in the
instruments of the grasshoppers (Figs. 5, 6), parts of
the legs and the wings. The sound may be intensified, as
in the bGdy of a stringed instrument, by special resonating
Fro. 8. The front wings, or tegmina, of a
meadow grasshopper, Orchelimum laticauda,
il[ustrating the sound-making organs typical
of the katydid farnily
_, left front wing and basal part of right wing
of maie, showing the four main veins: subcosta
(Se), radius (R), media (M), and cubitus (Cu);
also the enlarged basal vibrating area, or
tympanum (Tre), of each wing, the thick file
rein (ft') on the left, and the scraper (s) on
the rlght
B, lower surface of base of left wing of maie,
showing the file (]) on under side of the file
rein (A, fv)
C, right front wing of ferrmle, which bas no
sound-making organs, showing simple normal
venation
areas, sometimes on
the wings, sometimes
on the body. The
cicadas, a group of
musical insects to be
described in a special
chapter, have large
drumheads in the wall
of the body with
which they produce
their shrill music.
They do hot beat
these drums, but
cause them to vibrate
by muscles in the
body. The musical
members of the insect
familles are in nearly
ail cases the males,
and it is usually sup-
posed that they give
their concerts for the
purpose of engaging
the females, but that
this is so in ail cases
we can hot be certain.
The musical instru-
ments of the katydids
are quite different
from those of the
grasshoppers, being
situated on the over-
[341
THE GRASSHOPPER'S COUSINS
lapping bases of the Iront wings, or tegmina. On this
account the front wings of the males are alwavs different
flore those of the females, the latter retaining the usual or
primitive structure. The right wing of a female in one of
the more grasshopperlike species, Orchelimum laticauda
(Fig. 3o),is shown at C of Figure 8. Thewingis trav-
ersed by four principal veins springing flore the base.
The one nearest the inner
edge is called the cubitus
(Cu) and the space be-
tween it and this margin
of the wing is filled with
a network of small veins
having no particular ar-
rangement. In thewings
of the maie, however,
shown at A of the saine
figure, this inner basal ..f
field is much enlarged
and consists of a thin, C
crisp membrane (Tre),
braced by a number of
veins branching from the
cubitus (Cu). One of
these (fv), running cross-
wise through the mem-
brane, is very thick on
the left wing, and when
the wing is turned over
(B) it is seen to have a
close series of small cross-
ridges on its under sur-
face which convert it into
FIG. 19. Wings, sound-making organs,
and the "ears" of a conehead grasshopper,
Neoconocephalus ensiger, a member of the
katydid family
A, B, right" and left wings, showing the
scraper (s) on the right, and the file vein
fv) on the left. C, under surface of the
file vein, showing the file (f). D, front
leg, showing slits (e) on the tibia opening
into pockets containi.ng the hearing
organs (fig. :zo A)
a veritable file (f). On the right wing this saine rein is
much more slender and its file is very weak, but on the
basal angle of this wing there is a stiff ridge (s) hOt de-
veloped on the other. The katydids always fold the
[35]
INSECTS °
wings with the ]eft overlappingthe right, and in this position
the file of the former lies above the ridge (s) of the latter.
If now the wings are moved sidewise, thefile grating on the
ridge or scraper causes a rasping sound, and this is the way
the katydid makes the notes of its music. The tone and
w)lume of the sound, however, are probably in large part
produced by the vibration of the thin basal membranes of
the wings, which are called the t_vmpam (Tre).
The instruments of different players differ somewhat in
the details of their structure. There are variations in the
form and size of the file and the scraper on the wings of dif-
ferent species, and differences in the veins supporting the
tympanal areas, as shown in the drawings of these parts
from a conehead (Fig. 27) given at A, B, and C, of Figure
9- In the true katydid, the greatest singer of the family,
the file, the scraper, the tympana, and the wings them-
selves (Fig. 26) are ail ver)' highly developed to form an
instrument ofgreat efficiencv. But, in general, the instru-
ments of different species do hot differ nearlv so much as
do the notes produced (rom them bv their owners. An
endless number of tunes mav be played upon the saine
fiddle. With the insects each musician knows onlv one
tune, or a few simple variations of it, and this he bas in-
herited from his ancestors along with a knowledge of how
to play it on his inherited instrument. The stridulating
organs are hOt functionally developed until maturity, and
then the insect forthwith plays his native air. He never
disturbs the neighbors with doleful notes while learning.
Very curiously, none of the katydids nor any member of
their family ha ; the earlike organs on the sides of the body
possessed by the locusts. What are commonly supposed
to be their organs of hearing are located in their front legs,
as are the similar organs of the crickets. Two vertical
slits on the upper parts of the shins, or tibiae (Fig. i 9 D, e),
open each into a small pocket (Fig. 2o A, E) with a tym-
panumlike membrane (Tre) stretched across its inner wall.
Between the membranes are air cavities (Tra) and a coin-
[36 ]
THE GRASSHOPPER'S COUSINS
plicated sensorv receptive apparatus (B) connected by a
nerve through the basal part of the leg with the central
nervous system.
There are several groups of katydids, classed as sub-
Fie. o. The probable auditory organ of the front leg of Decticus,
a member of the katydid family. (Simplified from Schwabe)
Pi» cross-section of the leg through the auditory organ, showing
the ear slits (e, e) leading into the large ear cavities (E, E) with
the tympana (Tre, Tre) on their inner faces. Between the
tympana are two tracheae (Tra» Tra) dividing the leg cavity into
an upper and a iower channel (BC, BC). Tlie sensory apparatus
forms a crest on the outer surface of the inner trachea, each ele-
ment consisting of a cap cell (CCI), an enveloping cell (ECI) con-
taining a sense rod &o), and a sense ,.ell (8Cl). Ct, the thick
cuticula forming the hard wall of the leg
B, surface view of the sensory organ, showing the elements
graded in size from above downward. The sense oeils (8Cl) are
attached to the nerve (Nv) along the inncr side of the leg
families. A subfamily naine ends in inae to distinguish it
from a family naine, which, after the Latin fashion, termi-
nates in idae.
THE ROUND-HEADED KATYDIDS
The members of this first group of the katydid family
are characterized by having large wings and a smooth
[37]
INSECTS
round forehead. Thev compose the subfamily Phanerop-
terinae, which includés species that attain the acme of
grace, elegance, and refinement to be round in the entire
orthopteran order. Nearlv ail the round-headed katydids
ar musical to some degree, but their productions are not
Fro. OE. A bush katydid, Scuddtriafurcata
t'ppcr figure, a maie; Iowr, a female in the act of cleaning a
hind foot
of a high'order. On rhe other hand, though their notes
are in a high key, they are usuallv hot loud and hot of the
kind that keep you awake at night.
Among this group are the bush katydids, the species of
which are of medium size with slenderer wings than rhe
others, and are comprised in the genus usually known as
Scudderia but also called Ptzaneroptera. They bave ac-
quired the naine of bush katydids because they are usually
found on low shrubbery, particularly along the edges of
moist meadows, though they inhabit other places, too, and
their notes are often heard at nighr about the bouse. Out
I381
THE GRASSHOPPER'S COUSINS
commonest species, and one that occurs over most of the
United States, is the fork-tailed bush katydid (Scudderia
furcata). Figure 21 shows a male and a femme, the female
in the act of cleaning the pads on one of her hind feet. The
katydids are ail very particular about keeping their feet
clean, for it is quite essential to have their adhesive pads
always in perfect working order; but they are so con-
tinually stopping whatever they may be doing to lick one
foot or another, like a dog scratching fleas, that it looks
more like an ingrown habit with them than a necessary act
of cleanliness. The fork-tailed katydid is an unpreten-
tious singer and has only one note, a high-pitched zeep re-
iterated several times in succession. But it does not re-
peat the series continuously, as most other singers do, and
its music is likely to be lost to human ears in the general
din from the jazzing bands of crickets. Yet occasionally
its sort zeep, zeep, zeep may be heard from a near-by bush
or from the lower branches of a tree.
The notes of other species have been described as zikk,
zikk, zikk, or zeet, zeet, zeet, and some observers have re-
corded two notes for the saine species. Thus Scudder says
that the day notes and the night notes of Scudderia curvi-
cauda differ considerably, the day note being represented
by bzrwi, the night note, which is only hall as long as the
other, by tchw. (With a little practice the reader should
be able to give a good imitation of this katydid.) Scudder
furthermore says that they change from the day note to
the night note when a cloud passes over the sun as they are
singing by day.
The genus ztmblycorypha includes a group of species hav-
ing wider wings than those of the bush katydids. Most of
them are indifferent singers; but one, the oblong-winged
katydid (A/. oblongifolia), found over ail the eastern halfof
the United States and southern Canada, is noted for its
large size and dignified manners. A mme (Fig. _), kept
by the writer one summer in a cage, never once lost his
decorum by the humiliation of confinement. He lived ap-
[391
INSECTS
parently a natural and contented life, feeding on grape
leaves and on ripe grapes, obtaining the pulp of the latter
by gnawing holes through the skin. He was always sedate,
always composed, his motions always slow and deliberate.
In walking he carefully lifted each foot and brought the leg
forward with a steady movement to the new position,
where the foot was carefully set down again. Only in the
act of jumping did he ever make a quick movement of any
sort. But his preparations for the leap were as calm and
unhurried as his other acts: pointing the head upward,
dipping the abdomen slowly downward, the two long hind
legs bending up in a sharp inverted V on each side of the
body, he would lead one to think he was deiiberately pre-
paring to sit down on a tack; but, ail at once, a catch
seems to be released somewhere as he suddenly springs
upward into the leaves overhead at wh]ch he had talen
such long and careful aire.
For a long rime the aristocratic prisoner uttered no
sound, but at last one evening he repeated three rimes a
[40]
THE GRASSHOPPER'S COUSINS
squeaking note resembling shriek with the s much aspi-
rated and with a prolonged vibration on the ie. The next
evening he played again, making at first a weak swish,
swish, swish, with the s verv sibilant and the i very vibra-
tory. But after giving thi as a prelud, e he began a sh iii
shrie-e-e-e-k, shrie-e-e-e-k, repeated sx times, a loud
sound described by Blatchlev as a "creaking squawk-- like
the noise ruade by drawing a fine-toothed comb over a
taut string."
The best-known members of the round-headed katydids,
and perhaps of the whole familv, are the angular-winged
katydids (Fig. 23). These are large, maple-leaf green in-
sects, much flattened from side to side, with the leaflike
wings folded high over the back and abruptly bent on their
upper margins, giving the creatures the humpbacked ap-
pearance from which they get their name of angular-
winged katydids. The sloping surface of the back in front
of the hump makes a large fiat triangle, plain in the female,
but in the maie corrugated and roughened bv the veins of
the musical apparatus.
There are two species of the angular-winged katydids in
the United States, both belonging to the genus Microcen-
trum, one distinguished as the larger angular-winged katy-
did, 31. rhombifolium, and the other as the smaller angu-
lar-winged katydid, M. retinerve. The females of the
larger species (Fig. 23) , which is the more common one,
reach a length of 23. 8 inches measured to the tips of the
wings. They lay fiat, oral eggs, stuck in rows overlapping
like scales along the surface of some twig or on the edge
of a leaf.
The angular-winged katydids are attracted to lights and
may frequently be round on warm summer nights in the
shrubbery about the house, or even on the porch and the
screen doors. Members of the larger species usually make
their presence known by their sort but high-pitched notes
resembling tzeet uttered in short series, the first notes re-
peated rapidly, the others successively more slowly as the
[41 ]
INSECTS
tone becomes also less sharp and piercing. The song
may be written tzeet-tzeet-tzeet-tzeet-tzek-tzek-tzek-tzuk-tzuk,
though the high key and shrill tones of the notes must be
F*. 3- The larger angular-winged katydid, Microcentrum rhombifolium
Upper figure, a maie; lower, a female
imagined. Riley describes the song as a series of raspings
"as of a stiff quill drawn across a coarse file," and Allard
14]
THE GRASSHOPPER'S COUSINS
savs the notes "are sharp, snapping crepitations and sound
like the slow snapping of the teeth of a stiff comb as some
object is slowly drawn across it." He represents them
thus: tek-ek-ek-ek-ek-ek-ek-ek-ek-ek-ek-tzip. But, however
the song of Microcentrum is to be translated into English,
it contains no suggestion of the notes of his famous cousin,
the true katydid. Yet most people confuse the two species,
or rather, hearing the one and seeing the other, they draw
the obvious but erroneous conclusion that the one seen
makes the sounds that are heard.
The smaller angular-winged katydid, Jlicrocentrun reti-
r, erae, is hOt so frequently seen as the other, but it has simi-
lar habits, and may be heard in the vines or shrubbery
about the house at night, lts song is a sharp zeet, zeet, zeet,
the three syllables spaced as in ka-l.v-did, and it is probable
that many people mistake these notes for those of the true
katvdid.
"I;he angular-winged katydids are very gentle and un-
suspicious creatures, allowing themselves to be picked up
without an}" attempt at escaping. But they are good
ff.vers, and when launched into the air sail about like minia-
ture airplanes, with their large wings spread out straight
on each side. \¥hen at test thev have a comical habit of
leaning over sidewise as if their fiat forms were top-heavy.
"FHE TRUE KAT'DID
\,'e now corne to that artist who bears by right the naine
of "katydid," the insect /Fig. 2 4 ) known to science as
Pteroph.vlla camellfolia and to the American public as the
greatest of insect smgers. D,'hether the katydid is really a
musician or hot, of course, depends upon the critic, but of
his faine there can be no question, for his naine is a house-
hold terre as familiar as that of any of out own great
artists, notwithstanding that there is no phonographic
record of his music. To be sure, the cicada has more of a
world-wide reputation than the katydid, for he has repre-
sentatives in many lands, but he has hot put his song into
[431
]NSECTS
words the public can understand. And ifsimplicity be the
test of true art, the song of the katydid stands the test, for
nothing could be simpler than merely katy-did, or its easy
variations, such as katy, katy-she-did, and katv-didn't.
Yet though the music of the katydid is known by ear or
by reputation to almost every native American, few of us
FG. -4. The true katydid, Pterophylla camelloEolia, a maie
are acquainted with the musician himself. This is because
he almost invariably chooses the tops of the tallest trees for
his stage and seldom descends from it. His lofty platform,
moreover, is also his studio, his home, and his world, and
the reporter who would have a personal interview must be
efficient in tree climbing. Occasionally, though, it happens
that a singer may be located in a smaller tree where access
to him is easier or from which he may be dislodged by
shaking. A specimen, secured in this way on August
lived till October g and firnished material for the follow-
ing notes:
The physical characters of the captive and some of his
attitudes are shown in Figures 2 4 and 2 5. His length is
/4 inches from the forehead to the tips of the folded
wings; the front legs are longer and thicker than in most
other members of the family, while the hind legs are un-
usually short. The antennae, though, are extremely long,
slender, and very delicate filaments, 2'3/,6 inches in length.
[44]
THE GRASSHOPPER'S COUSINS
13
Fc. =.ç. The katydid in various attitudes
A, usua[ position of a maie while singlng. B, attitude v¢hile running rapidly on
a smooth surface. C, preparing to [eap from a vertical surface. D, a maie,
seen from above, showing the stridulating area at the base of the wings. E, a
female, showing the broad, fiat. curved ovipositor
[451
INSEC'I'S
Between the bases of the antennae on the forehead there
is a small conical pro.jection, a physical character which
separates the true katydid from the round-headed katy-
dids and assigns him to the subfamily called the Pseudo-
phyllinae, which includes, besides our species, many others
that live mostly in the tropics. The rear margins of the
wings are evenly rounded and their sides strongly bulged
outward as if to cover a very plump body, but the space
between them is mostlv empty and probably forms a
resonance chamber to give tone and volume to the sound
produced by the stridulating parts. What might be the
katydid's waistcoat, the part of the bodv exposed beneath
the wings, has a row of prominent buttonlike swellings
along the middle which rhythmically heave and sink with
each respiratory movement. Ail the katydids are deep
abdominal breathers.
The color of the katvdid is plain green, with a conspicu-
ous dark-brown triangl'e on the back covering the stridulat-
ing area of the wings. The tips of the mouth parts are
vellowish. The eyes are of a pale transparent green, but
each has a dark center which, like the pupil in a painting, is
alwavs fixed upon you from whatever angle you retreat.
The movements of the captive individual are slow,
though in the open he can run rather rapidly, and when he
is in a hurry he often takes the rather absurd attitude
shown at B of Figure 25, with the head down and the
wings and bodv elevated. He never flies, and was never
seen to spread ]is wings, but when making short leaps the
wings are slightly fluttered, in preparing for a leap, if
only one of a few inches or a foot, he makes very careful
preparations, scrutinizing the proposed landing place long
and closely, though perhaps he sees better in the dark and
acts then with more agility. If the leap is tobe ruade
from a horizontal surface, he slowlv crouches with the legs
drawn together, assuming an attitude more familiar in a
car; but, if the jump is tobe from a vertical support, he
raises himself on his long front legs as at Cof Figure 25,
[46l
THE GRASSHOPPER'S COUSINS
suggesting a camel browsirg on the leaves of a tree. He
sparingly eats leaves of oak and maple supplied to him in
his cage, but appears to prefer fresh fruit and grapes, and
relishes bread soaked in water. He drinks rather less than
most orthopterons.
When the katydids are singing at night in the woods they
appear to be most wary of disturbance, and often the voice
of a person approaching or a crackle underfoot is sufl:icient
to quiet a singer far overhead. The maie in the cage never
utters a note until he bas been in darkness and quiet for a
considerable time. But when he seems to be assured of
solitude he starts his music, a sound of tremendous volume
in a room, the tones incredibly harsh and rasping at close
range, lacking entirely that melody they acquire with space
and distance. It is only by extreme caution that the per-
former may be approached while singing, and even then
the brief flash of a light is usuallv enough to silence those
stentorian notes. Yet occasionally a glimpse may be had
of the musician as he plays, most frequently standing head
downward, the bodv braced rather stiffly on the legs, the
front wings onlv slghtly elevated, the tips of the hind
wings projectin a little from between them, the abdomen
depressed and breathing strongly, the long antennal
threads waving about in all directions. Each syllable ap-
pears to be produced by a separate series of vibrations
ruade bv a rapid shuPrting of the wings, the middle one be-
ing more hurried and the last more conclusivelv stressed,
thus producing the sound so suggestive of ka-t.v-'did', ka-tv-
did', which is repeated regularly about sixty times a minu-te
on warm nights. Usually at the start, and often for some
rime, only two notes are uttered, ka-t.v, as if the player bas
diflîculty in falling at once into the full swing of ka-tv-did.
The structure of the wings and the details of the s}ridu-
lating parts are shown in Figure 26. The wings (A, B) fold
vertically against the sides of the body, but their inner
basal parts form wide, stiff, horizontal, triangular flaps that
overlap, the left on top of the right. A thick, sunken,
[47]
INSECTS
crosswise vein (fv) at the base of the left tympanum (7,) is
the file rein. It is shown from below at C where the
broad, heavy file (f) is seen with its row of extremely
coarse raspmg ridges. The saine rein on the right wing
(B) is lnuch smaller and bas no file, but the inner basal
angle of the tyn{panum is pro.duced into a large lobe bear-
mg a strong scraper (s) on its
"Sç s m a rgl n.
R
B
'I(;. 6. Wings and the sound-mak-
ing organs of the maie katydid
A, left front wing, showing the greatly
enlarged tympanal area (Tre), with its
thick file rein (#). B, base of right
fore wing, with large scraper («) on its
inn«r angle, but with a very small file
rein. C, under surface of file rein of
left wing, showing the large, fiat,
coarsely-ribbed file (t')
the notes, but one lacking in
artist of such repute. In New England, the katydids
heard bv the writer in Connecticut and in the western
part of Massachusetts uttered only two syllables much
[48]
The quality of the katv-
did's song seems to diffC
somewhat in different parts
of the country. In the vicin-
itv of Wash'ington, the in-
sects certainlv sav ka-tv'-did
as plainly as any insect could.
Of course, the sound is lnore
literallv to be represented as
ka ki-kak', accented on the
last svllable. When only two
svllab]es are pronounced they
are alwavs the tirst two.
Sometime's an individua] in a
hand utters four syllable.s,
"katv-she-did" or ka a.i-lea-
kak','and again a whole band
is heard singing in four notes
with onlv an occasiona]
singer givi;g three. It is said
that in certain parts of the
South the katvdid is called
a "cackle-jak," a naine
which, it must be adlnitted,
is a verv literal translation of
sentiment and t,nbefittilg an
THE GRASSHOPPER'S COUSINS
more commonly than three, and the sounds were extremelv
harsh and rasping, being a loud squ-wk', squ-wk',
squ-wk', the second svllable a little longer than the first.
This is hot the case wit] those that s.y ka-tv. When there
were three syllables the series was squ-w-wk'. If ail
New England katydids sing thus, itis hot surprising that
some New England writers have failed to see how the
insects ever got the naine of "katvdid." Scudder says
"their notes have a shocking lack'of melodv"; he rep-
resents the sound by xr, and records that the song is
usually of onlv two syllables. "That is," he says, " they
rasp their fore wings twice rather than thrice; these
two notes are of equal (and extraordinary) emphasis, the
latter about one-quarter longer than the former; or if three
notes are given, the first and second are alike and a little
shorter than the last."
When we listen to insects singing, the question always
arises of why they sing, and we might as well adroit that
we do hot know what motive impels them. It is prob-
ably an instinct with males to use their stridulating organs,
but in many cases the tones emitted are clearly modified by
the physical or emotional state of the player. The music
seems in some wav to be connected with the mating of the
sexes, and the ustial idea is that the sounds are attractive
to the females. With many of the crickets, however, the
real attraction that the maie has for the female is a liquid
exuded on his back, the song apparently being a mere ad-
vertisement of his wares. In any case the ecstacies of love
and passion ascribed to maie insects in connection with
their music are probably more fanciful than real. The
subject is an enchanted field wherein the scientist bas
most often weakened and wandered from the narrow
path of observed facts, and where he bas indulged in a free-
dom of imagination permissible to a poet or to a newspaper
reporter who wishes to enliven his chronicle of some event
in the dailv news, but which does hot contribute anything
substantia] to our knowledge of the truth.
[49]
INSECTS
THE CONEH EADS
This group of the katydid (amily contains slender,
grasshopperlike insects that bave the forehead produced
Flç. OE7" A conehead grasshopper, or katydtd, Neocono-
cephalus retusus
Upper figure, a maie; Iower, a female, with extremelv long
ov*positor
into a large
cone and the
face strongly
receding, but
which also pos-
sess long, slen-
der antennae
that distinguish
them from the
true or short-
horn grasshop-
pers. They con-
stitute the sub-
family Copi-
phorinae.
One of the
commonest and
most widely
distributed of
the larger cone-
heads ls the
species known as Neoconocephalus ensiger, or the "sword-
bearing conehead." It is the female, however, that carries
the sword; and it is hot a sword either, but merely the
immensely long egg-laying instrument properly called the
ovipositor. The female conehead shown at B of Figure "-7,
bas a similar organ, though she belongs to a species called
retusus. The two species are very similar in all respects
except for slight differences in the shape of the cone on the
head. They look like slim, sharp-headed grasshoppers,
J  to J3/44 inches in length, usually bright green in color,
though sometimes brown.
15oi
THE GRASSHOPPER'S COUSINS
The song of ensiger sounds like the noise of a miniature
sewing machine, consisting merelv of a long series of one
note, tick, tick, tick, tick, etc., repeated indefinitelv.
Scudder says ensiger begins with a note like brw, then
pauses an instant and immediatelv
emits a rapid succession of sounds
like chwi at the rate of about rive
per second and continues them an
unlimited rime. lX.IcNeil repre-
sents the notes as zip, zip, zip;
Davis expresses them as ik, ik,
and Allard hears them as tsiD, tsip,
tsip. The song ofretusus (Fig. 7)
is quite different. It consists of a
long shrill whir which Rehn and
Hebard describe as a continuous
zeeeeeeeeee. The sound is hot loud
but is in a very high key and rises
in pitch as the player gains speed
in his wing movements, till to some
human ears it becomes almost in-
audible, though to others it is a \
plain and distinct screech.
A large conehead and one with
a much stronger instrument is the
robust conehead, .\'eoconocepha/tts
robttsttts (Fig.  '
-). He is one of
the [oudest singers of North
American ()rthoptera, his song
being an intense, continuous buzz, Fro. =8. The rob.st cone-
head, Neoconocephalus robus-
s«maewhat resembling thar of a tu*, in position ofsinging, with
cicada. A caged specimen singing çor wings separated and
in a room makes a deafening noise, somewhat elevated, the head
downward
The principal buzzing sound is ac-
companied by a lower, droning hum, the origin of which
ls hot clear, but which is probably some secondary vibra-
tion of the wings. The player alwavs sits head downward
15,1
INSECTS
while performing, and the breathing motions of the abdo-
men are very deep and rapid. The robust conehead is an
inhabitant of dry, sandy places along the Atlantic coast
from Massachusetts to Virginia and, according to Blatch-
ley, of similar plac.es near the shores of Lake Michigan in
Indiana. The wnter made its acquaintance n Con-
necticut on the sandv flats of the uinnipiac Valley, north
of New Haven, where its shrill song may be heard on
summer nights from long distances.
THE MEADOW GP,.ASSHOPPERS
These are trim, slim little grasshopperlike insects, active
by day, that lire in moist meadows where the vegetation is
always fresh and juicy. They constitute the subfamily
Conocephalinae of the katydid family, having conical
FIG. 9- The common meadow grasshopper, Orchelimum vulgare, a member of
the katydid family
heads like the last group, but being mostly of smaller size.
There are numerous species of the meadow grasshoppers,
but most of them in the eastern part of the United States
belong to two genera known as Orche/imum and Conoceph-
ahLs. The most abundant and most widely distributed
member of the first is the common meadow grasshopper,
Orchelimum ,ulgare. A maie is shown in Figure 9- He
is a little over an inch in length, with head rather large
for his size and with big eves of a bright orange color. The
ground color of his body" is greenish, but the top of the
head and the thoracic shield is occupied by a long tri-
angular dark-brown patch, while the stridulating area of
[5oEl
THE GRASSHOPPER'S COUSINS
Fro. 3o. The hand-
some meadow grass-
hopper, Orchelimum
laticauda
Upper figure, a maie;
ower, a femae
the wings is marked bv a brown
spot at each corner. "J'hese little
grasshoppers readilv sing in con-
finement, both in tae day and at
night. Their music is verv unpre-
tentious and might easilv be lost
out of doors, consisting mostly of a
sort, rustling buzz that ]asts two or
three seconds. Often the buzz is
preceded or followed bv a series of
clicks ruade bv a slower movenlent
of the wings. Frequently the
player opens the wmgs for the
start of the song with a single click,
then proceeds with the buzz, and
finallv closes with a few slow
movements that produce the con-
cluding series of clicks. But very
commonlv he gives onlv the buzz
without prelude
or staccato end-
ing.
Another com-
mon member of
the genus is the
agile meadow
grasshopper, Or-
che/imum e«gi/e.
l ts music is said
tobe a long zip,
zip, zip, ze«-«-«-«,
with the zip syl-
lable repeated manv times. These two
elements, the zip and zee, are charac-
teristic of the songs of ail the Orcheli-
mures, some giving more stress to the
first and others to the second, and
Fro. 3,. The slender
meadow grasshopper,
Conocephalus fasciatus,
one of the smalest
members of the katy-
did famiy
[531
INSECTS
sometimes either one or the other is omitted. A verv
pretty species of the genus is the handsome meadow
grasshopper, Orcl, eHml«m latical«d« (or pdchellum) shown
m Figure 30.. When at test, both males and females
usuallv sit close to a stem or leaf with the middle of the
bodv n contact with the support and the long hind legs
stretched out behind. Davis savs the song of this species
is a zip, zip, zip, , , .., quite ditinguishable flore that of
O. çwlgare.
Still smaller meadow grasshppers belong to the genus
Cozoc@hah, s, more commonlv called .Viphidil«m. One of
the most abundant species, the slender meadw grass-
hopper, C../asciatus, is shwn in Figure 3 - It is less than
an inch in length, the bodv green, the back of the thorax
dark brown, the wings redlish-brown, and the back of the
abdomen marked with a broad bmwn stripe. Allard says
the song of this little meadow grasshpper may be ex-
pressed as tip, tip, tip, tseeeeeeeeeeeeee, but that the entire
song is so faint as almost to escape the hearing. Piers
describes it as ple-e-e-e-e-e, tz#, tzit, tzit, tzit. l.ike the song
of Orchelimz«m ,u/gare it apparently mav either begin or
end with staccato notes.
THE SHIELD BEARERS
Another large group of the katvdid family is the sub-
familv Decticinae, mostlv cricketl'ike insects that lire on
the ground, but which bave wings so short (Fig. 3"-) that
they are poor musicians. They are called "shield bearers"
because the large back plate of the first body segment is
more or less prolonged like a shield over the back. Most of
the species live in the western parts of the United States,
where the individuals sometimes become so abtmdant as
to form large and very destructive bands. One such
species is the Mormon cricket, .tnabrus simplex, and an-
other is the Coulee cricket, Perambrus scaricollis (Fig. 32),
o(the dry central region of the State of Washington. The
females of these species are commonly wingless, but the
[54]
THE GRASSHOPPER'S COUSINS
males have short stubs of front wings that retain the
stridulating organs and enable them to sing with a brisk
chirp.
Still another large subfamilv of the Tettigoniidae is the
Fro. 3oEE. The Coulee cricket, Perauabrus srbri¢ollis, maie and female, an
e×ample of a cricketlike member of the katydid family
Rhadophorinae, including the insects known as "camel
crickets." But these are ail wingless, and therefore silent.
TI-IE CRICKET I¢AlXlIL',"
The chirp of the cricket is probably the most familiar
note of ail orthopteran music. But the only cricket com-
monly known to the public is the black field cricket, the
lively chirper of out vards and gardens. His European
cousin, the house cricket, is famous as the "cricket on the
hearth" on acconnt of his fondness for fireside warmth
which so stimulates him that he must express his animation
in song. This bouse cricket bas been known as Gryllus
since the time of the ancient Greeks and Romans, and his
naine has been ruade the basis for the naine of his family,
the Gryllidae, for there are numerous other crickets, some
that live in trees, some in shrubbery, some on the ground,
and others in the earth.
The crickets bave long slender antennae like those of the
katydids, and also stridulating organs on the bases of the
wings, and ears in their front legs. But they differ from the
katydids in having only three .ioints in their feet (.Fig.
17 C). The cricket's foot in this respect resembles the foot
[SSl
INSECTS
of the grasshopper (A), but usually differs from that of the
grasshopper in having the basal joint smooth or hairy ail
aroundor with only one pad on the under surface. In most
crickets, also, the second joint of the foot is very small.
OEAC du
Sc l:L i,
Cu(fv) i 
C c,,  D c
Fe. 33- The wings of a tree cricket
A, right front wing of an immature female, showing normal arrangement of
veins: 8r, subcosta; R, radius; ./, media; Cut, first branch of cubitus;
second branch of cubitus; zH, first anal. (From Comstock and Needham)
B, front wing of an adult female of the narrow-winged tree cricket
C, front wing of an immature maie, showing widening of inner hall to form
vibrating area, or tympanum, and modification of veins in this area. (From
Comstock and Needham)
D, right front wing of adult maie of the narrow-winged tree cricket; the second
branch of cubitus (Cu.-) becomes the curved file rein ([v); s, the scraper
Some crickets have large wings, some small wings, some no
wings at ail. The females are provided with long oviposi-
tors for placing their eggs in twigs of trees or in the ground
(Figs. 35, 36) •
The musical or stridulating organs of the crickets are
similar to those of the katydids, being formed from the
veins of the basal parts of the front wings. But in the
crickets the organs are equally developed on each wing, and
it looks as if these insects could play with either wing up-
permost. Yet most of them consistently keep the right
[s6l
THE GRASSHOPPER'S COUSINS
wing on top and use the file of this wing and the scraper
of the left, just the reverse of the custom among the
katvdids.
"lahe front wings of maie crickets are usually very broad
and have the outer edges turned down in a wide flap that
folds over the sides of the body when the wings are closed.
The wings of the females are simpler and usually smaller.
The differences between the front wings in the maie and
the female of one of the tree crickets (Fig. 37) is shown
at B and D of Figure 33. The inner half of the wing (or
the rear half when the wing is extended) is very large in the
maie (D) and has only a few veins, which brace or stiffen
the wide membranous vibratory area or t_vmpanlm. The
inner basal part, or a,lal area, of the maie wing is also
larger than in the female and contains a prominent rein
(CI«_) which lnakes a sharp curve toward the edge of the
wing. This rein has the stridulating file on its under sur-
face. The veins in the wing of an
adult female (B) are comparatively
simple, and those of a young female (A)
are more so. But the complicated
venation of the maie wing has been de-
veloped from the simple type of the
female, which is that common to in-
sects in general. The wing of a young
maie (C) is hot so different from that
of a young female (A) but that the cor-
responding veins can be identified, as
shown by the lettering. Taking next
the wing of the adult maie (D), it is an
easv marrer to determine which veins
Fro.a4. A rnole cricket,
bave been distorted to produce the N««rtitta a,*Z*«tt*
stridulating apparatus. When the tree
crickets sing thev elevate the wings above the back like
two broad fans (igs. 37, 4 °) and move them sidewise so
that the file of the right rubs over the scraper of the
left.
[57]
INSECTS
THE MOLE CRICKETS
The mole crickets (Fig..34) are solemn creatures of the
earth. They lire like true moles in burrows underground,
usually in wet fields or along streams. Their forefeet are
broad and turned outward for digging like the iront feet of
moles. But the mole crickets differ from real moles in
having wings, and sometimes thev leave their burrows at
night and fly about, being occasionally attracted to lights.
Their front wings are short and lie fiat on the back over
the base of the abdomen, but the long hind wings are
folded lengthwise over the back and project beyond the tip
of the body.
Notwithstanding the gloomy nature of their habitat, the
maie mole crickets sing. Their music, however, is solemn
and monotonous, being alwavs a series of loud, deep-toned
chirps, like churp, churp, cAurp, repeated very regularly
about a hundred rimes a minute and continued indefinitelv
if the singer is hot disturbed. Since the notes are most
frequently heard coming from a marshy field or from the
edge of a stream, they might be supposed to be those of a
small frog. It is diPficult to capture a mole cricket in the
act of singing, for he is most likely standing at an opening
in his burrow into which he retreats before he is discovered.
THE FIELD CRICKETS
This group of crickets includes Grvllus as its typical
member, but entomologists give firstplace to a smaller
brown cricket called Nemobms. There are numerous spe-
cies of this genus, but a widely distributed one is N. ïitta-
tus, the striped ground cricket. This is a little cricket,
about three-eighths of an inch in ]ength, brownish in color,
with three darker stripes on the abdomen, common in
fields and dooryards (Fig. 35)- In the fall the females lay
their eggs in the ground with their slender ovipositors
(D, E) and the eggs (F) hatch the following summer.
The song of the maie Nemobius is a continuous twitter-
[58]
THE GRAS.'.;H()PPER'S CO[ IN.";
/
F
D
Fç. 3- The striped ground cricket, NemoMus "oittatus
A, B, fema]es, distinguished by the long ovipositor. Ci a maie. D, a fema]e
in the act of thrusting her ovipositor in to the ground. E, a female, with oviposi-
tor fui] length in the ground, and extruding an egg from its tip. F, an eggin
the ground
ing trill so faint that you must listen attentively to hear it.
In singing the maie raises his wings at an angle of about
45 °. The stridulating vein is set with such fine ridges that
[591
INSECTS
they would seem incapable of producing even those whis-
permg Nemobius notes. Most of the muscial instruments
of insects can be ruade to produce a swish, a creak, or a
grating noise of some sort when handled with our clumsy
fingers or with a pair of forceps, but only the skill of the
living insect can bring from them the tones and the volume
of sound they are capable of producing.
Our best-known cricket is Gryllus, the black cricket
(Fig. 36), so common everywhere in fields and yards and
occasionally entering houses. The true house cricket of
Europe, Grvllus domesticus, bas become naturalized in this
country anal occurs in small numbers through the Eastern
States. But out common native species is Grvllus. assimilis.
Etomologists distinguish several varieties, though thev
are inclined to regard them ail as belonging to the one
species.
Mature individuals of Gryllus are particularly abundant
in the fall; in southern New Egland they appear every
year at this season by the millions, swarming everywhere,
hopping across the country roads in such numbers that it is
impossible to ride or walk without crushing them. Most
of the females lay their eggs in September and October, de-
positing them singly in the ground (Fig..]6 D, E) in the
saine way that Nemobius does. These eggs hatch about
the first ofJune the following year. But at this saine rime
another group of individuals reaches maturity, a group
that hatched in midsummer of the preceding year and
passed the winter in an immature condition. The males of
these begin singing at Washington during the last part of
May, in Connecticut the first of June, and may be heard
until the end of June. Then there is seldom anv sound of
Gryllus until the middle of August, when the males of the
spring group begin to mature. From now on their notes
become more and more common and by early rail they are
to be heard almost continuouslv day and night until frost.
The notes of Grvllus are always vivacious, usually cheer-
fui, sometimes angry in tone. They are merelv chirps, and
[6o1
THE GRASSHOPPER'S COUSINS
may be known from ail others by a broken or vibratory
sound. There is little music in them, but the player has
enough conceit to make up for this lack. Two vigorous
Flc. 3 6. The comrnon black cricket, Gryllus assimilis
A, a rnale with wings raised in the attitude of singing. B, a female with long
- ovipositor. C, young crickets recently hatched (enlarged about 2 rimes).
D, a female inserting her ovipositor in the ground. E, a female with ovipositor
buried full length in the ground
[6,1
INSECTS
males that were kept in a cage together with several
females gave each other little peace. Whenever one began
to play his fiddle the other started up, to the plain disgust
of the first one, and either was always greatly annoyed and
provoked to anger if any of the females happened to run
into him while he was playing, lfone male was fiddling
alone and the other approached him, the first dashed at
the intruder with jaws open, increasing the speed of his
strokes at the saine rime till the notes became almost a
shrill whistle. The other male usuallv retaliated by play-
ing, too, in an apparent attempt to outfiddle the first. The
chirps flore both sides now came quicker and quicker, their
pitch mounting higher and higher, till each player reached
his limit. Then both would stop and begin over again.
Neither maie ever inflicted any actual damage on his rival,
and in spire of their savage threats neither was ever seen
really to grasp any part of the other with hisjaws. Ether
would dash madly at a female that happened to disturb
him while fiddling, but neither was ever seen to threaten a
female with open jaws.
The weather bas much influence on the spirits of the
males; their chirps are alwavs loudest and their rivalry
keenest when it is bright and warm. Setting their cage in
the sun on «)ld days always started the two males at once
to singing. Out of doors, though the crickets sing in all
weather and at ail hours, variations of their notes in tone
and strength according to the temperature are very notice-
able. This is hot owing to anv effect of humiditv on their
instruments, for the two belligérent males kept in the bouse
never had the retaper on cold and gloomy days that char-
acterized their actions and their song on days that were
warm and bright. This, in connection with the fact that
their music is usuallv aimed at each other in a spirit clearly
suggestive of vindiciveness and anger, is ail good evidence
that Grvllus sings to express/limse/.[ and hot to "charm the
females." In fact, it is often hard to feel certain whether
he is singing or swearing. If we could understand the
1621
THE GRASSHOPPER'S COUSINS
words, we might be shocked at the awful language he is
hurling at his rival. However, swearing is only a form of
emotional expression, and singing is another. Gryllus,
like an opera singer, simply expresses ail his emotions in
music, and, whether we can understand the words or not,
we understand the sentiment.
At last one of the two caged rivals died; whether from
natural causes or by foui means was never ascertained.
He was alive early on the dav of his demise but apparently
weak, though still intact. In the middle of the afternoon,
however, he lay on his back, his hind legs stretched out
straight and stiff; only a few movements of the front legs
showed that life was not yet quite extinct. One antenna
was lacking and the upper lip and adjoining parts of the
face were gone, evidently chewed off. But this is hot neces-
sarily evidence that death had followed violence, for, in
cricketdom, violence more commonly follows death; that
is, cannibalism is substituted for interment. A few days
before, a dead female in the cage had been devoured
quickly, ail but the skull. After the death of this maie,
the remaining one no longer fiddled so often, nor with the
saine sharp challenging tone as before. Yet this could hot
be attributed to sadness; he had despised his rival and had
clearlv desired to be rid of him; his change was due rather
to the lack of any special stimulus for expression.
THE TREE CRICKETS
The unceasing ringing that alwavs rises on summer eve-
nings as soon as the shadows begin to darken, that shrill
melody of sound that seems to corne from nothing but
from everywhere out of doors, is mostly the chorus of the
tree crickets, the blend of notes from innumerable harpists
playing unseen in the darkness. This sound must be the
most famiIiar of ail insect sounds, but the musicians them-
selves are but little known to the general public. And
when one of them happens to corne to the window or into
the house and plays in solo, the sound is so surprisingly
[631
INSECTS
loud that the player is hot suspected of being one of that
band whose mingled notes are heard outside softened by
distance and mufiqed by screens of foliage.
Out of doors the music of an individual cricket is so
elusive that even when you think you have located the ex-
Fro. 37- The snowy tree cricket, Oecanthus niveus
The upper figures, males, the one on the right with fore wings
raised vertically in attitude of singing below, a female, with
narrow wings folded close against the body
act bush or vine from which it comes the notes seem to
shift and dodge. Surely, you think, the player must be
under that leaf; but when you approach your ear to it, the
sound as certainly cornes from another over yonder; but
here you are equally convinced that it cornes from still
[641
THE GRASSHOPPER'S COUSINS
another place farther off. Finally, though, it strikes the
ear with such intensity that there can be no mistaking the
source ofits origin, and, right there in plain sight on a leaf
sits a little, delicate, slim-legged, pale-green insect with
hazy, transparent sails outspread above its back. But
can such an insignificant creature be making such a deafen-
ing sound! It has required very cautious tactics to ap-
proach thus close without stopping the music, and it needs
but a touch on stem or leaf to make it cease. But now
those gauzy sails that before were a blurred vignette have
acquired a definite outline, and a little more disturbance
may cause them to be lowered and spread fiat on the
creature's back. The music will not begin anew until you
have passed a period of silent waiting. Then, suddenly,
the lacy films go up, once more their outlines blur, and
that intense scream again pierces your ear. In short, you
are witnessing a private performance of the broad-winged
tree cricket, Oecanthus latipennis.
But if you pay attention to the notes of other singers,
you will observe that there is a variety of airs in the medley
gomg on. Many notes are long trills like the one just
identified, lasting indefinitely; but others are softer purr-
ing sounds, about two seconds in length, while still others
are short beats repeated regularly a hundred or more times
every minute. The last are the notes of the snowy tree
cricket, Oecanthus niveus, so-called on account of his pale-
ness. He is really green in color, but a green of such a
very pale shade that he looks almost white in the dark. The
maie (Fig. 37) is a little longer than hall an inch, his wings
are wide and fiat, overlapping when folded on the back,
with the edges turned down against the sides of the body.
The female is heavier-bodied than the maie, but her wings
are narrow, and when folded are furled along the back.
She has a long ovipositor for inserting her eggs into the
bark of trees.
The males ofthe snowy cricket reach maturity and begin
to sing about the middle of July. The singer raises his
[65]
INSECTS
wings vertically above the back and vibrates them sidewise
so rapidly that they are momentarily blurred with each
note. The sound is that treat, treat, treat, treat already de-
scribed, repeated regularly, rhythmically, and monoto-
nously all through the night. At the first of the season
there may be about  5 beats every minute, but later, on
hot nights, the strokes become more rapid and mount to
6o a minute. In the fall again the rate decreases on cool
evenings to perhaps a hundred. And finally, at the end of
the season, when the players are benumbed with cold, the
D C D
F«. 3 8. Distinguishing marks on the basal segments of the
antennae of common species of tree crickets
A, B» narrow-winged tree cricket, Otcanthus angustiptnnis.. C,
snowy tree cricket, niveus. D, four-spotted tree cricket, nigri-
cornis çuadripunctatus. E, black-horned tree cricket, nigricornis.
F, broad-winged tree cricket, latiptnnis
notes become hoarse bleats repeated slowly and irregularly
as if produced with pain and difficulty.
The several species of tree crickets belonging to the
genus Oecanthus are similar in appearance, though the
males differ somewhat in the width of the wings and some
species are more or less diffused with a brownish color.
But on their antennae most species bear distinctive marks
(Fig. 38) by which they may be easily identified. The
snowy cricket, for example, bas a single oral spot of black
on the under side of each of the two basal antennal joints
(Fig. 38 C). Another, the narrow-winged tree cricket, bas
[66]
THE GRASSHOPPER'S COUSINS
a spot on the second.joint and a black J on the first (A, B).
A third, the four-spotted cricket (D), has a dash and dot
side by side on each joint. A fourth, the black-horned or
striped tree cricket (-lï), bas tvèo spots on each joint more
or less run together, or sometimes has the whole base of
the antenna blackish, while the color may also spread over
the fore parts of the body and, on some individuals, form
Fç...19- Maie and female of the narrow-winged tree cricket, Oecanthus angusti-
The female is feeding on a liquid exuded from the back of the maie, while the
latter holds his fore wings in the attitude of singing. (Enlarged about 3 times}
stripes along the back. A fifth species, the broad-winged
(F), has no marks on the antennae, which are uniformly
brownish.
The narrow-winged tree cricket (Oecanthus angusti-
permis) is almost everywhere associated with the snowy,
but its notes are very easily distinguished. They consist
of slower, purring sounds, usually prolonged about two
seconds, and separated by intervals of the same length, but
as rail approaches they become slower and longer. Always
thev are sad in tone and sound far off.
The three other common tree crickets, the black-horned
or striped cricket, Oecanthus ngricornis, the four-spotted,
[67]
INSECTS
Flç. #o. A maie of the broad-
winged tree crlcket, Oecanthu
latipennis, with wings elevated
in position ofsinging, seen from
above and behind, showing
the basin (B) on bis back into
which the liquid is exuded that
attracts the female
O. nigricornis quadripunctatus,
and the broad-winged, O. lati-
permis, are ail trillers; that is,
their music consists of a long,
shrill whir kept up indefinitely.
Of these the broad-winged cricket
makes the loudest sound and the
one predominant near Washing-
ton. The black-horned is the
common triller farther north, and
is particularly a daylight singer.
In Connecticut his shrill note
rings everywhere along the road-
sides, on warm bright afternoons
of September and October, as the
player sits on leaf or twig fully
exposed to the sun. At this
season also, both the snowy and
the narrow-winged sing by day
but usually later in the after-
noon and generally from more concealed places.
We should naturally like to know why these little
creatures are such persistent
singers and of what use their
music is to them. Do the males t
really sing to charm and attract
the females as is usually pre-
sumed? We do not know; but
sometimes when a maie is sing-
ing, a female approaches him
flore behind, noses about on his
back, and soon finds there a d.eep
basinlike cavity situated just
Fc.. 41. The back of the
behind the bases of the elevated third thoracic segment of the
wings. This basin contains a broad-winged tree cricket,
with its basin (B) that receives
clear liquid which the female secretionfromtheglands(GI)
proceeds fo lap up very eagerly, inside the body
168]
THE GRASSHOPPER'S COUSINS
as the maie remains quiet with wings upraised though he
bas ceased to play (Fig. 39). We must suspect, then, that
in this case the female has been attracted to the maie
rather by his confectionerv offering than by his music.
The purpose of the latter, tJaerefore, would appear to be to
advertise to the female the whereabouts of the maie, who
she knows has sweets to offer; or if the liquid is sour or
bitter it is all the same--the female likes it and cornes
after it. If, now, this luring of the female sometimes ends
in marriage, we mav see here the real reason for the male's
possessing his mus'ic-making organs and his instinct to
play them so continuouslv.
A male cricket with h[s front wings raised, seen from
above and behind as he might look to a female, is shown in
Figure 4 o. The basin (B) on his back is a deep cavity on
the dorsal plate of the third thoracic segment. A pair of
large branching glands (,Fig. 4, GI) within the body open
just inside the rear lip of the basin, and these glands fur-
nish the liquid that the female obtains.
There is another kind of tree cricket belonging to an-
other genus, Neoxabia, called the two-spotted tree cricket,
N. bipunctata, on accourir of two pairs of dark spots on the
wings of the female. This cricket is larger than any of the
species of Oecanthus and is of a pinkish brown color. It is
widelv distributed over the eastern hall of the United
States, but is comparatively rare and seldom met with.
Allard savs its notes are low, deep, mellow trills con-
tinued for" a few seconds and separated by short intervals,
as are the notes of the narrow-winged Oecanmus, but that
their tone more resembles that of the broad-winged.
THE BUSH CRICKETS
The bush crickets differ from the other crickets in having
the middle joint in the foot larger and shaped more like the
thirdjoint in the foot ofa katydid (Fig. 7 B). Among the
bush crickets there is one notable singer common in the
neighborhood of Washington. This is the jumping bush
[691
INSECTS
cricket, Orocharis saltator (Fig. 4z), who cornes on the stage
late in the season, about the middle of August, or shortly
after. His notes are loud, clear, piping chirps with a rising
inflection toward the end, suggestive of the notes of a
srnall tree toad, and they at once str]ke the listener as
sornething new and
different in the insect
prograrn. The play-
ers, however, are at
first very hard to lo-
cate, for they do hot
-_ perform continuously
--one note seerns to
corne frorn here, a
 second from over
there, and a third
frorn a different an-
gle, so that it is al-
rnost impossible to
place any one of
thern. But after a
week or so the crick-
Fiç. 4- The lumping bush cricket, Orocharis
saltator ets becoITle more nu-
Upper figure, a maie; lower, a female ITlerous and each
player more persistent till soon their notes are the predorni-
nant sounds in the.nightly concerts, standing out loud and
clear against the whole tree-cricket chorus. As Riley says,
this chirp "is so distifictive that when once studied it is
never lost arnid the louder racket of the katydids and
other night choristers."
After the first of Septernber it is hot hard to locate one of
the perforrners, and when discovered with a flashlight, he is
round to be a rnediurn-sized, brown, short-legged cricket,
built sornewhat on the style of Grvllus but srnaller (Fig.
49-). The maie, however, while snging raises his wings
straight up, after the rnanner of the tree crickets, and he
too, carries a basin ofliquid on his back rnuch sought after
[7 ° ]
THE GRASSHOPPER'S COUSINS
by the female. In fact the liquid is so attractive to her
that, at least in a cage, she is sometimes so persistent in her
efforts to obtain it that the maie is clearly annoyed and
tries to avoid her. One maie was observed to say very
distinctly by his actions, as he repeatedly tried to escape
the nibbling of a female, presumably his wife since she was
taken with him when captured, "I do wish you would quit
pestering me and let me sing!" Here is another piece of
evidence suggesting that the maie cricket sings to express
his own emotions, whatever they may be, and hot pri-
marily to attract the female. But if, as in the case of the
tree crickets, his music
tells the female where
she may find her favorite
confection, and this in
turn leads to matrimony,
when the male is in the
proper mood, it suggests
a practical use and a rea-
son for the stridulating
apparatus and the song
of the maie insect.
[71 ]
V'A LKI NG-STIc KS AND
I.EA " INSECTS
Talent often seems to
run in familles, or in re-
lated familles, but it does
hot necessarily express it-
self in the saine wav. If
the katydids and crickets
FIG. 43" The common walking-stick in-
are noted musicians, sect, Diapheromera femorata, of theeastern
some of their relatives, var, of the United States. (Length 
belonging to the family
Phasmidae, are incomparable mimics. Their mimicry,
however, is hot a conscious imitation, but is one bred in
their bodily forms through a long line of ancestors.
INSECTS
If sometime in the woods you should chance to see a
short, slender piece of twig suddenly corne to lire and
slowiv walk away on six slim legs, the marvel would not be
a miracle, but a walking-stick in-
sect (Fig. 43). These insects are
fairly common in the eastern parts
of the United States, but on ac-
count of their resemb]ance to
twigs, and their habit ofremaining
perfectly quiet for a long time
with the body pressed close to a
branch of a tree, they are more
frequently overlooked than seen.
Sometimes, however, they occur
locally in great numbers. It is
supposed that the stick insects so
closely resemble twigs for the pur-
pose of protection from their
enemies, but it has hot been shown
just what enemies they avoid by
their elusive shape. The stick in-
sects are more common in the
South and in tropical countries,
where some attain a remarkable
length, one species flore Affica,
for example, being eleven inches
long when full-grown. In New
Guinea there lives a species that
looks more like a small club than
FIG. 44- A gigantic spiny
walking-stickinsect, Eury- a stick, it being a large, heavy-
canthus horrida, from New bodied, spm.y creature, nearly
Guinea. (Length g3" SiX inches m length and an
inches)
inch in width through the thick-
est part of its body (Fig. 44)-
Other members of the phasmid family have specialized
on imitating leaves. These insects have wings in the
adult stage, and, of course, the wings make it easier for
[7"-1
THE GRASSHOPPER'S COUSINS
them to take the form of leaves. One famous species that
lives in the East Indies looks so much like two leaves stuck
together that it is truly marvelous that an insect could be
so fashioned (Fig. 45). The
whole body is fiat, and about
three inches long, the bases of
the legs are broad and irregu-
larly notched, the abdomen is
spread out almost as thin as a
real leaf, and the leafiike wings
are held close above it. Finally,
the color, which is leaf-green
or brown, gives the last touch
necessary for complete dissim-
ulation.
TIqE Mar'rltS
I t is often observed that
genius may be perverted, or
put to evil purposes. Here is a
family of insects, the Man-
tidae, related to the grass-
hoppers, katydids, and crick-
Fro. 45. A tropical leaf insect,
Pulchriph.vllium pulchrfoliurn, a
mernber of the walking-stick farn-
ily. (Length 3 inches)
ets, the members of which are clever enough, but are
deceitful and malicious.
The praying mantis, Stagmomantis carolina (Fig. 46),
though he may go by the aliases of "rear-horse" and
"soothsayer," gets his more common naine from the
prayerful attitude he commonly assumes when at rest.
The long, necklike prothorax, supporting the small head,
is elevated and the front legs are meekly folded. But if
you examine closely one of these folded legs, you will see
that the second and third parts are armed with suspicious-
looking spikes, which are concealed when the two parts
are closed upon each other. In truth, the mantis is an
arch hypocrite, and his devotional attitude and meek
looks betoken no humility of spirit. The spiny arms,
[731
IN  ECTS
so innocently folded upon the breast, are direful weapons
held ready to strike as soon as some unsuspecting insect
happens within their reach. Let a small grasshopper
corne near the posing saint: immediately a sly tilt of the
head belles the suppliant manner, the crafty eyes leer
upon the approaching insect, losing no detail of his
movements. Then, suddenly, without warning, the pray-
ing mantis becomes a demon in action. With a nice cal-
culation of distance, a swift movement, a snatch of the
Fro. 4 6. The praying mantis, 8tagmomantis carolina, and remains of its
last meal. (Length v..* inches)
terrible clasps, the unlucky grasshopper is a doomed
captive, as securelv held as if a steel trap had closed upon
his body. As rhe'hapless creature kicks and wrestles, the
jaws of the captor sink inro the back of his head, evidently
in search of the brain; and hardlv do his weakening strug-
gles cease belote the victim isdevoured. Legs, wings,
and other fragments unsuitable to the taste of an epicure
are thrown aside, when once more the mantis sinks into
repose, piously folds his arms, and meekly awaits the
[741
THE GRASSHOPPER'S COUSINS
chance arrival of the next ..... --
course in his ever unfinished "' /
banquet of living fare. « / .....
Some exotic species of
mantids have the sides of kil II
the prothorax extended to
forma wide shield (Fig. 47),
beneath which the forelegs
are folded and completely
hidden. It is hot clear what
advantage they derive from
this device, but it seems to
be one more expression of
deceit.
Of course, as we shall
take occasion to observe
later, goodness
ness are largely
FG. 48. Egg case of a
mantis attached to a
twig, 8ta.momantis
carolina
and bad- Fro. 47. A mantis from Ecuador with
matters of a shieldlike extension of its back.
(Length 3' inches)
relativity.
The mantis is an evil creature from the
standpoint of a grasshopper, but he
would be regarded as a benefactor by
those who bave a grudge against grass-
hoppers or against other insects that the
mantis destroys. Hence, we must reckon
the mantis as at least a beneficial insect
relative to human welfare. A large
species of mantis, introduced a few years
ago into the eastern States from China,
is now regarded as a valuable agricul-
rural asset because of the number of
harmful insects it destroys.
The mantids lay their eggs in large
cases stuck to the twigs of trees (Fig. 48).
The substance of which the case is ruade
is similar to that with which the locusts
inclose their eggs, and is exuded from the
[751
INSECTS
bodv of the female mantis when the eggs are laid. The
young mantids are active little creatures, without wings
but with long legs, and it is the rate of those unprotected
green bugs, the aphids, or plant lice, that in(est the leaves
of almost ail kinds of plants, to become the principal
victims of their vouthful appetites.
[76]
CHAPTER 11I
ROACHES AND OTHER ANCIENT INSECTS
,''E used to speak quite confidentlv of time as something
definite, measurable bv the clock, and of a vear or a cen-
tury as specific quantities ofduration. In ttiis present age
of relativity, however, we do hot feel so certain about these
things. Geologists calculate in years the probable age of
the earth, and the length of time that has elapsed since
certain events took place upon it, but their figures mean
only that the earth has gone around the sun approximately
so many rimes during the interval. ! In biology it signifies
nothing that one animal has been on the earth for a million
years, and another for a hundred million, for the unit of
evolution is hot a year, but a generation. If one animal,
such as most insects, has from one to many generations
every year, and another, such as man, has only four or rive
in a century, it is evident that the first, by evolutionary
reckoning, will be vastly older than the second, even
though the two have ruade the saine number of trips with
the earth around the sun. An insect that antedates man
by several hundred million years, therefore, is ancient
indeed.
The roach scarcely needs an introduction, being quite
well known to ail classes of society in every inhabited part
of the world. That he has long been established in human
communities is shown bv the fact that the various nations
have bestowed different names tapon him. His common
English naine of "cockroach" is said to corne from the
Spanish, cucaracha. The Germans call him, rather di,s-
respectfully, Kiichenschabe, which signifies "kitchen
[771
INSECTS
louse." The ancient Romans called him Blatta, and on
this his scientific familv naine of Blattidae is based. A
small species of Europe, named by rhe entomologisrs
C
Fc. 49- The four species of common household roaches
A, the German roach, or Croton bug, Blattella gerrnanica (length N inch). B,
the American cockroach, Periplaneta arnericana (length 3s inches). C, the
Australian cockroach, Periplaneta australasiae (length i/ci/ inches). D, the
wingless female of the Oriental roach, Blatta orientalis (length i/ inches). E,
the winged maie of the Oriental roach (length  inchl
[78]
ROACHES AND OTHER ANCIENT INSECTS
Blattella germanica, which isnow our most common
American roach, received the nickname of "Croton bug"
in New York, because somehow he seemed to spread with
the introduction of the Çroton Valley water system, and
this appelation has stuck to him in many parts of the
cotm try.
The Croton bug, or German roach ('Fig. 49 A), is the
smallest of the "domestic" varieties of roaches. It is
that rather slender, pale-brown species, about five-eighths
of an inch in length, with the two dark spots on the front
shield of its body. This roach is the principal pest of the
kitchen in the eastern part of the United States, and prob-
C
A B
FIG. 50. Egg cases of rive spectes of roaches. (Twice natural size)
A, egg case of the Australian roach (fig. 49 C). B, that of the American
roach (fig. 49 B); the other three are ruade by out-of-door species
ably the best support of the trade in roach powders. Sev-
eral other larger species are fortunately less numerous,
but still familiar enough. Among these are one called
the American roach (Fig. 49 B), a second known as the
Australian roach (C), and a third as the Oriental roach
(D, E). These four species of cockroaches are all great
travelers and recognize no ties of nationality. They are
equally at home on land and at sea, and, as uninvited
[791
INSECTS
passengers on ships, they have spread to ail countries
where ships bave gone.
Besides the household roaches, there are great numbers
of species that lire out of doors, especially in warm and
tropical regions. Most of these are plain brown of various
shades, or blackish, but some are green, and a few are
spotted, banded, or striped. Different species vary much
in size, some of the largest reaching a length of four inches,
measured to the tips of the folded wings, while the smallest
are no longer than three thirty-seconds of an inch in
length. They nearly ail bave the familiar flattened form,
with the head bent down beneath the front part of the
body, and the long, slender antennae projecting forward.
Most species bave wings which they keep closely folded
over the back. In the Oriental roach, the wings of the
female are very short (Fig. 49 D), a character which gives
them such a different appearance from the males (E) that
the two sexes were formerly supposed to be differen t species.
The roach, of course, was hot designed to be a household
insect, and it lived out of doors for ages before man con-
structed dwellings, but it happens that its instincts and its
form of body particularly adapt it to a lire in bouses. Its
keen sense, its agility, its nocturnal habits, its omnivorous
appetite, and its flattened shape are ail qualities very
fitting for success as a domestic pest.
Many kinds of roaches give birth to living young; but
most ofour common species lay eggs, which they inclose in
hard-shelled capsules. The material of the capsule is a
tough but flexible substance resembling horn, and is pro-
duced as a secretion by a special gland in the body of the
female opening into the egg duct. The capsule is formed
in the egg duct, and the eggs are discharged into it while
the case is held in the orifice of the duct. When the re-
ceptacle is full its open edge is closed, and the eggs are thus
tightly sealed within it. The sealed border is finely
notched, and transverse impressions on the surface of the
capsule indicate the position of the eggs within it.
[ 8ol
ROACHES AND OTHER ANCIENT INSECTS
The Croton bug, or German roach (Fig. 49 A), makes a
small fiat tabloid egg case, which the female usually carries
about with her for some time projecting from the end of
her body, and sometimes the eggs hatch while she is still
carrylng the case. The American and Australian roaches
(Fig. 49 B, C) make egg cases much resemblin miniature
pocketbooks or tobacco pouches, about three-eighths or
halfan inch in length, with a serrated clasp along the upper
edge (Fig. 5 ° A, B). The cases of some of the smaller
species of roaches are only one-sixteenth of an inch long
FiG. 51. Young of the German roacia, or Croton bug (fig. 49 A), m various
stages just before and after hatching
A, the young roach in the egg just before hatching. B, the young roach just
after hatching, shedding its embryonic covering membrane. C, young roach
after shedding the embryonic covering. D, the saine individual hall an hour old
(C), while larger species may make a case three-quarters
of an inch in length (È).
The embryo roaches mature within the eggs, and when
they are ready to hatch they emerge inside the egg case.
By some means, the roughened edge of the case where it
was last closed is opened to allow the imprisoned insects
to escape. Small masses of the tiny creatures now bulge
out, and finally the whole wriggling contents of the cap-
sule is precting from the dit. First one or two indi-
viduals free themselves, then several together rail out,
then more of them, until soon the case containing the
empty eggshells is deserted.
[8]
INSECTS
\Vhen the young roaches first liberate themselves from
the capsule, they are helpless creatures, for each is con-
tained in a close-fitting membrane that binds its folded
legs and antennae tightly to the body and keeps the head
pressed down against the breast (Fig. 5I A). The inclos-
ing sheath, however, a film so delicate as to be almost
invisible, is soon burst by the struggling of the little roach
anxious to be free--it splits and rapidly slides down over
the bodv (B), from which it is at last pushed off. The
shrunken, discarded remnant of the skin is now such an
insignificant flake that it scarce seems possible it so re-
cently could have enveloped the body of the insect.
The newly liberated young roach dashes off on its slim
legs with an activity quite surprising in a creature that bas
never had the use of its legs belote. It is so slender of
figure (Fig. 5  C) that it does hot look like a roach, and it is
pale and colorless except for a mass of bright green material
m its abdomen. But, almost at once, it begins to change;
the back plates of the thorax flatten out, the body shortens
by the overlapping of its segments, the abdomen takes on
a broad, pear-shaped outline, the head is retracted be-
neath the prothoracic shield, and by the end of hall an
hour the little insect is unmistakably a young cockroach
(D).
The roaches bave a potent enemy in the bouse centipede,
that creature of so many legs ('Fig. 5) that it looks like
an animated blur as it occasionally darts across the living-
room floor or disappears in the shades of the basement
before vou are sure whether you bave seen something or
hot, but which is often trapped in the bathtub, where its
appearance is likely to drive the housewife into hysteria.
[.nless you are fond of roaches, however, the bouse centi-
pede should be protected and encouraged. The writer
once placed one of these centipedes in a covered glass dish
containing a female Croton bug and a capsule of ber eggs
which were hatching. No sooner were the young roaches
running about tban tbe centipede began a feast which
[J
ROACHES AND OTHER ANCIENT INSECTS
ended only when the last of the brood had been devoured.
The mother roa(h was not at the time molested, but next
morning she lay dead on her back, her head severed and
dragged some distance from the
body, which was sucked dry of
its juices--mute evidence of the
tragedy that had befallen some-
time in the night, probably when
the pangs of returning hunger
stirred the centipede to renewed
activitv. The bouse centipede
does hot confine itself to a diet of
live roaches, for it will eat almost
any kind of food, but itis never
a pest of the household larder.
Most species of roaches have
two pairs of well-developed
wings, which thev ordinarily keep
folded over the back, for in their
usunl pursuits the domestic spe-
cies do hot often fly, except oc-
casionallv when hard pressed to
avoid capture. The front wings
are longer and thicker than the
hind wings, and are laid over the
latter, which are rhin and folded
fanwise when not in use. 111 these
characters the roaches resemble
the grasshoppers and katydids,
and their famih', the Blattidae, is
Fro. ç2. The common house
centipede, &tligtra forctps
natural size), a destroyer of
young roaches
usually placed with these insects in the order Orthoptera.
The wings of insects are interesting objects to studv.
When spread out fiat, as are those of the roach shown in
Figure 53, thev are seen to consist of a thin membranous
tissue strengtlened by manv branching ribs, or veins,
extending outward from the base. The wings of ail insects
are constructed on the saine general plan and have the
[831
INSECTS
saine primary veins; but, since the great specialty of in-
sects is flight, in their evolution they bave concentrated
on the wings, and the different groups bave tried out
different styles of venation, with the result that now
each is dist]nguished by some particular pattern in the
arrangement of the vems and their branches. The
entomologist can thus hot onlv distinguish by their wing
structure the various orders o(insects, as the Orthoptera,
the dragonflies, the moths, the bees, and the flies, but in
F*ç. _ç'. Wings of a cockroach, Periplaneta, showing the rein
pattern characteristic of the roach family
manv cases he can identifv families and even genera.
Part"cularlv ;tre the wings ol  value to the student of fossil
insects, for the bodies are so poorly preserved in most
cases that without the wings the paleontologist could
bave ruade little headwav in the studv of insects of the
past. As it is, however, much is knowa of insects of
former times, and a studv of their fossil remains bas con-
tributed a great deal to our knowledge of this most
versatile and widespread group of animais.
[841
ROACHES AND OTHER ANCIENT INSECTS
The paleontological history of life on the earth shows
us that the land bas been inhabited successively by
different forms of animais and plants. A particular group
of creatures appears upon the scene, first in comparative
insignificance; then it increases in numbers, in diversity
of forms, and usually in the size of individuals, and may
become the dominant form of lire; then again it falls
back to insignificance as its individuals decrease in size,
its species in numbers, until perhaps its type becomes
extinct. Meanwhile another group, representing another
type of structure, cornes into prominence, flourishes, and
declines. It is a mistake, however, to get the impression
that ail forms of life have had this succession of up and
down in their history, for there are manv animais that
have existed with little change for immense periods of
rime.
The history of insects gives us a good example of per-
manence. The insects must have begtm tobe insects
somewhere in those remote periods of time before the
earliest known records of animais were preserved in the
rocks. They must bave been present during the age when
the water swarmed with sharks and great armored fishes;
they certainly flourished during the era when our coal
beds were being deposited; thev saw the rise of the huge
amphibians and the great reptilian beasts, the Dinosaurus,
the l«hth),osaurus, the Plesiosaurus, the .losasaurus, and
ail the test of that monster tribe whose names are now
familiar household words and whose bones are to be seen
in ail our museums. The insects were branching out
into new forms during the time when birds had teeth and
were being evolved from their reptile ancestors, and when
the flowering plants were beginning to decorate the land-
scape; they were present from the beginning of the age
of mammals toits culmination in the great fur-bearing
creatures but recently extinct; they attended the advent
of man and have followed man's whole evolution to the
present rime; they are with us yet--a vigorous race that
INSECTS
shows no sign of weakening or of decrease in numbers.
Of ail the land animais, the insects are the true b[ue-blood
aristocrats by length of pedigree.
The first remains of insects known are found in the
upper beds of the rocks laid down in the geological period
of the earth's history known as the Carboniferous. Dur-
Fro. 5,t. A group of common Carboniferous plants reaching the sze and pro-
portions of large trees. (From Chamberlin and Salisbury, drawn by Mildred
1Marvin from restorations of fossil specimens.) Courtesy of Henry Hoir & Co.
Of the two large trees in the foreground, the one on the left is a Sigillaria, that
on the right a Lepidodendron; of the two large central trees in the background
the left 3 a Cordaite's, the right a tree fern; the rail stalks in the outermost circle
are Calamites, plants related to our horsetail ferns
ing Carboniferous rimes much of the land along the
shores of inland seas or lakes was marshy and supported
great forests from which our coal deposits have been
formed. But the Carboniferous landscape would have
had a strange and curious look to us, accustomed is we
1861
ROACHES AND OTHER ANCIENT INSECTS
are to an abundance of hard-wood, leafy trees and shrubs,
and a multitude of flowering plants. None of these
forms of vegetation had yet appeared.
lXluch of the undergrowth of the Carboniferous swamps
was composed of fernlike plants, many of which were,
indeed, true ferns, and perhaps the ancestors of our
modern brackens. Some of these ancient ferns grew to
a great size, and rose above the rest in treelike forms, at-
taining a height of sixty feet and more, to branch out
in a feathery crown of huge spreading fronds. Another
group of plants characteristic of the Carboniferous flora
comprised the seed ferns, so named because, while closely
resembling ferns in general appearance, thev differed
from true ferns in that they bore seeds instead of spores.
The seed ferns were mostly small plants with delicate,
ornate leaves, and they have left no descendants to modern
times.
Along with the numerous ferns and seed ferns in the
Carboniferous swamps, there were gigantic club mosses,
or lycopods, which, ascending to a height sometimes of
much more than a hundred feet, were the conspicuous big
trees in the forests of their day (Fig. 54)- These lycopods
had long, cvlindrical trunks covered with small scales
arranged in regular spiral rows. Some had thick branch-
ing limbs starting from the upper part of the trunk and
closelv beset with stiff, sharp-pointed leaves; others
bore at the top of the trunk a great cluster of long slender
leaves, giving them somewhat the aspect of a gigantic
varietv of our present-day yucca, or Spanish bayonet.
The bases of the larger trees expanded to a diameter of
three or four feet, and were supported on huge spreading
underground branches from which issued the roots--a
device, perhaps, that gave them an ample foundation in
the soft mud of the swamps in which they grew.
The Carboniferous lycopods furnished most of our coal,
and then, in later times, their places were taken by other
types of vegetation. But their race is not yet extinct,
INSECTS
for we have numerous representatives of them with us
today in those lowly evergreen plants known as club
mosses, whose spreading, much-branched limbs, usually
trailing on the ground, are covered bv rows of short,
stiff leaves. The most familiar of the club mosses, though
hot a typical species, is the "ground pine." This humble
little shrub, so much sought for Christmas decoration,
still in some places carpets our woods with its sort, broad,
frondlike stems. In the fall when its rich dark green
so pleasingly contrasts with the somber tones of the
season's dying foliage, it seems tobe an expression of
the vitality that has preserved the lycopod race through
the millions of years which have elapsed since the days of
its great ancestors. The "resurrection plant," often sold
to housekeepers under false or exaggerated claires of a
marvelous capacity for rejuvenation, is also a descendant
of the proud lycopods of ancient rimes.
In our present woodlands, along the banks of streams
or in other moist pl.aces, there grows also another plant
that has been preserved to us from the Carboniferous
forests--the common "horsetail fern," or Equisetum, that
green, rough-ribbed stalk with the whorls of slender
branches growing from its joints. Out equisetums are
modest plants, seldom attaining a height of more than a
few feet, though in South American countries some species
may reach an altitude of thirty feet; but in Carboniferous
rimes their ancestors grew to the stature of trees (Fig. 54)
and measured their robust stalks with the trunks of the
lycopods and giant ferns.
Aside from the numerous representatives of these sev-
eral groups of plants, ail more or less allied to the ferns,
the Carboniferous forests contained another group of
treelike plants, called Cordaites, from which the cycads
of later times and out present-day maidenhair tree, or
ginko, are probably descended. Then, too, there were a
few representatives of a type that gave origin to out
modern conifers.
[88]
ROACHES AND OTHER ANCIENT INSECTS
It is probable that a visitor to those davs of long ago
might give us a more complete account of he vegetation
that grew in the Carboniferous swamps than can be known
from the records of the rocks, but the paleobotanist bas
a wealth of material now at hand suflîcient to give us
at least a pretty reliable picture of the setting in which
the earliest of known insects lived and died.
And now, what were the insects like t.hat inhabited
the forests of those early rimes? Were they, too, strangel
fashioned creatures, fit denizens of a far-off fairyland?
No, nothing of the sort, at least hot in appearance or
structure, though "fit" they probably were, from a physi-
cal standpoint, for insects are fitted to lire almost any-
where. In short, the Carboniferous insects were prin-
cipally roaches! Yes, those woods and swamps of millions
of years ago were alive with roaches little different from
our own familiar household pests, or from the numerous
species that bave hot forsaken their native habitats for
lire in the cities.
Whoever looks to the geological records for evidence
of the evolution of insects is sorelv disappointed, for
even in the venation of the wings those early roaches
(Fig. 55) were almost identical with our present species
(Fig. 5.])- As typical examples of the Carboniferous
roaches, the species shown in Figure 55 serve well, and
anyone can see, even though the specimens lack antennae
and legs, that the creatures were just common roaches.
Hence, we can easily picture these ancient roaches scut-
tling up the rail trunks of the scaly lycopds, and shuffling
in and out among the bases of the close-set leaf stems
of the tree ferns, and we shou]d expect to find an abundant
infestation of them in the vegetational refuse matted on
the ground, lnsects of those days must have been com-
paratively free from enemies, for birds did hot yet exist,
and ail that host of parasitic insects that attack other
insects were not evolved until more recent rimes.
Though by far the greater number of the Carboniferous
[89]
I N SECTS
insects known are roaches, or insects closely related to
roaches, there were many other forms besides. Some of
these are of particular interest to entomologists because,
in some ways, they are more simple in structure than are
B
Fro. 5g. Fossil cockroaches from Upper Carboniferous rocks
A, tls«oalatta zona, round in lllinois, length of wing one inch.
(From Handlirsch after Scudder.) B, Pkvloalatta caronaria,
round in Germany. (From Handlirsch)
any of the modern insects, and in this respect they ap-
parently stand doser to the hypothetical primitive insects
than do any others that we know. And yet, the charac-
ters by which these oldest known insects, called the
Paleodictyoptera, differ from modern forms are so slight
that thev would scarcdv be noticed bv anvone except
an entomo]ogist; to the casua] observer, the Paleodic-
tyoptera would be just insects. Their chief distinguish-
ing marks are in the pattern of the wing venation, which
is more symmetrical than in other winged insects, and,
therefore, probably closer to that of the primitive ances-
tors of ail the winged insects. These ancient insects
probably did hot fold the wings over the back, as do most
present-day insects, showing thus another primitive
[9ol
ROACHES AND OTHER ANCIENT INSECTS
character, though nota distinctive one, since rnodern
dragonflies (Fig. 58) and rnayflies (Fig. 60) likewise
keep the wings extended when at test.
The question of how insects "acquired wings is always
one of special interest, since, while we know perfectly
well that the wing of a bird or of a bat is rnerely a rnodi-
fied fore lirnb, the nature of the primitive organ frorn
which the insect wing bas been evolved is still a rnystery.
The Paleodictyoptera, however, may throw light upon
the subject, for sorne of thern had srnall fiat lobes on the
lateral edges of the back plate of the prothorax, which in
fossil specirnens look like undeveloped wings (Fig. 56).
The presence of these prothoracic lobes, occurring as they
do in sorne of the oldest known insects, bas suggested the
56. Examples of the earliest known fossil insects, called the Paleodic-
tyoptera, having small lobes (a) projecting like wings from the prothorax
8tenodictya lobata (from Brongniart). B, EuMeptus danielsi (drawn from
specimen in U. S. Nat. Mus.): TI, T,, Ta, back plates of three thoraclc segments
idea that the true wings were evolved from similar flaps
of the rnesothorax and rnetathorax. If so, we rnust pic-
ture the irnrnediate ancestors of the winged insects as
creatures provided with a row of three flaps on each side
of the body projecting stiffly outward frorn the edges of
the thoracic segrnents. Of course, the creatures could
not actually fly with wings of this sort, but probably
[9']
INSECTS
they could glide through the air flore the branches of one
tree to another as well as cana modern flying squirrel bv
means of the folds of skin stretched along the sides of its
bodv between the fore and the hind legs. If such lobes
the/ became flexible at their bases, it required only a
slight adjustment of the muscles already present in the
bodv to give them motion in an up-and-down direction;
and the wings of modern insects, in most cases, are still
moved bv a very simple mechanism which has involved
the acquisition of few extra muscles.
It appears, however, that three pairs of fully-developed
wings would be too many for mechanical eflïciency. In
the later evolution of insects, therefore, the prothoracic
lobes were never developed beyond the glider stage, and
in ail modern insects this first pair of lobes bas been lost.
Furthermore, it was subsequently found that swift flight
is best attained with a single pair of wings; and nearly
ail the more perfected insects of the present rime bave
the hind pair of wings reduced in size and locked to the
front pair to insure unity of action. The files bave
carried this evolution toward a two-winged condition so
far that thev bave practically achieved the goal, for with
them the h]nd wings are so greatly reduced that they
no longer bave the form or function of organs of flight, and
these insects, named the Diptera, or two-winged insects,
fly with one highly specialized and eflïcient pair of wings
(Fig.  67).
The Paleodictyoptera became extinct by the end of the
Çarboniferous period, and their disappearance gives
added support to the idea that they were the last sur-
vivors of an earlier type of insect. But they were by
no means the primitive ancestors of insects, for, in the
possession of wings alone, they show that they must bave
undergone a long evolution while wings were in the course
of development; but of this stage in the history ofinsects
we know nothing. The rocks, so far as bas yet been
revealed, contain no records of insect life below the upper
[9 z ]
ROACHES AND OTHER ANCIENT INSECTS
beds of the Carboniferous deposits, when insects were
already fully winged. This fact shows how cautious
we must be in making negative statements concerning
the extinct inhabitants of the earth, for we know that
insects must have lived long before we have evidence of
their existence. The absence of insect fossils earlier than
the Carboniferous is hard to explain, because for millions
of years the remains of other animais and plants had
FtG. 57- Machilis, a modern representative of ancient insects before the
development of wings. ¢Length of body s inch)
been preserved, and have since been round in compara-
tive abundance. As a consequence, we bave no concrete
knowledge of insects before thev became winged creatures
evo]ved almost to their modern form.
At the present time there are wingless insects. Some
of them show clearlv that thev are recent descendants
from winged forms." Others suggest bv their structure
that their ancestors never had wings. Such as these,
therefore, mav have corne down to us bv a long line of
descent from "the primitive wingless ancestors of all the
insects. The common "fish moth," known to entomolo-
gists as Lepisma, and its near relation, Machilis (Fig. 57),
:tre familiar examples of the trulv wingless insects of the
present time, and if their remote ancestors were as fragile
and as easilv crushed as they, we mav see a reason why
they never lft their impressions in the rocks.
Along with the Carboniferous roaches and the Paleo-
dictyoptera, there lived a few other kinds of insects,
manv of which are representative of certain modern
[93]
INSECTS
[94]
ROACHES AND OTHER ANCIENT INSECTS
groups. Among the latter were dragonflies, and some of
these must have been of gigantic size, for insects, because
they attained a wing expanse of fully two feet, while the
largest of modern dragonflies do not measure more than
eight inches across the expanded wings. But the length
of wing of the extinct giant dragonflies does not necessarily
mean that the bulk of the body was much greater than
that of the largest insects living today. In general, the
insects of the past were of ordinary size, the majority of
them probably matching with insects of the present time.
The modern dragonflies (Fig. 58) are noted for their
rapid flight and for the ability to make instantaneous
changes in the direction of their course while flying.
These qualities enable them to catch other insects on the
wing, which constitute their food. Their wings are pro-
vided with sets of special muscles, such as other insects
do not possess, showing that the dragonflies are descended
along a line of their own from their Carboniferous pro-
genitors. They still retain a character of their ancestors
in that they are unable to fold the wings fiat over the back
in the manner that most other insects fold their wings
when they are hot using them. The larger dragonflies
hold the wings straight out from the sides of the body
when at rest (Fig. 58); but a group of slender dragonflies,
known as the damselflies (Plate , Fig. .), bring the wings
together over the back in a vertical plane.
The dragonflies are usually found most abundantly in
the neighborhood of open bodies of water. Over the
unobstructed surface of the water the larger sp.ecies find
a convenient hunting ground; but a more important
reason for their association with water is that they lay
their eggs either in the water or in the stems of plants
growing in or beside it. The young dragonflies (Fig. 59)
are aquatic and must have an easy access to water. They
are homely, often positively ugly, creatures, having none
of the elegance of their parents.. They feed on other
living creatures which their swlmmlng powers enable
[951
INSECTS
them to pursue, and which they capture by means of
grasping hooks on the end of their extraordinarily long
underlip (Fig. 134 A), which can be shot out in front of
the head (B). The great swampy lakes of Paleozoic times
must have furnished an ideai habitat for dragonflies, and
[ZIG- 59" A young dragon-
fly, an aquatic creature
that leaves the water only
when ready to transform
into the adult (fig. 58)
it is probable that the most ancient
dragonflies known had a structure
and habits not very different from
those of modern species.
Another very common insect of
the present time, which appears
likewise to be a direct descendant
of Paleozoic ancestors, is the may-
flv (Fig. 60). The young mayflies
(lig. 6) also liv-e in the water, and
are provided with giils for aquatic" "
breathing, having the form of flaps
or filaments situated in a row along
each side of the body. The adults
(Fig. 60) are very delicate insects
with four gauzy wings, and a pair
of long threadlike taiis projecting
from the rear end of the body. At
the rime of their transformation
they often issue in great swarms
from the water, and they are par-
ticularly attracted to strong lights.
For this reason large numbers of them corne to the cities
at night, and in the morning they may be seen sitting
about on walls and windows, where they find themselves
in a situation totallv strange to their native habits and
instincts. The mayf]ies do hot fold their wings horizon-
tally, but when at test bring them together verticallv
over the back (Fig. 60). In this respect they, too, appear
to preserve a character of their Paleozoic ancestors;
though it must be observed that the highly evolved
modern butterflies close their wings in the saine fashion.
[961
ROACHES AND OTHER ANCIENT INSECTS
The roaches, the dragonflies, and the mayflies attest
the great antiquity of insects, for since these forms ex-
isted practically as thev are today in Paleozoic times, the
primitive ancestors of'ail the insects, of which we bave
no remains in the geological records, must bave lived in
times vastlv more remote. However, though we may
search in vain the paleontological records for evidence
of the origin and earlv development of insects, the subq
sequent evolution of the higher forms of modern insects
is clearly shown by the species preserved in eras later
t
Fxo. 6o. A mayfly, representative of another order of primitive
winged insects having numerous relations in Paleozoic rimes.
(Twice natural size)
than the Carboniferous. Such insects as the beetles,
the moths, the butterflies, the wasps, the bees, and the
files are entirely absent in the older rocks, but make their
appearance at later periods or in comparatively recent
rimes, thus confirming the idea derived from a study of
their structure that they bave been evolved from an-
cestors more closely resembling the paleodictyopteran
types of the Carboniferous beds.
The long line of descent of the roach, with almost no
change of form or structure, furnishes material for a
special lesson in evolution. If evolution has been a
[971
INSECTS
matter of survival of the fittest, the roach, judged by
survival, must be a most fit insect. Its fitness, however,
is of a general nature; it is one that adapts the roach to
lire successfully in many kinds of conditions and circum-
stances. Most other forms of mod-
Fie,. 6I. ,ai young mayfly,
a water-inhabiting crea-
rure. (One-half larger
than natural size)
ern insects bave been evolved
through an adaptation to more
special kinds of habitats and to
particular ways of living or of feed-
mg. Such insects we say are
spccialized, while those exemplified
in the roach are said to be general-
ized. Survival, therefore, may de-
pend either on generalization or on
specialization. Generalized forms
of animais bave a better chance of
surviving through a series of chang-
ing conditions than has an animal
which is specifically adapted to one
kind of life, though the latter mav
bave an advantage as long as con-
ditions are favorable to it.
The roaches, therefore, have sur-
vived to present times, and will
probably lire as long as the earth is
habitable, because, when driven
from one environment, they make
themselves at home in another; but we have ail seen how
the specialized mosquito disappears when its breeding
places are destroyed. From this consideration we can
draw some consolation for the human race, if we do hot
mind likening ourselves to roaches; for, as the roach,
man is a versatile animal, capable of adapting himself to
ail conditions of living, and of thriving in extremes.
[98]
CHAPTER IV
WAYS AND MEANS OF LIVING
IN our hunàan society each individual must obtain the
things necessary for existence; the manner bv which he
acquires them, whether by one trade or another, by this
means or by that, does hOt physica]ly matter so long as he
provides himself and his familv with food, clothing, and
shelter. Exactly so it is wita all forms of lire. The
physical demands of living matter make certain things
necessary for the maintenance of lire in that matter, but
nature has no law specifying that any necessity shall be
acquired in a certain manner. Lire itself is a circum-
scribed thing, but it bas complete freedom of choice in
the ways and means of living.
It is useless to attempt to make a definition of what
living matter is, or ofhow it differs from non-living matter,
for ail definitions bave failed to distinguish animate from
non-animate substance. But we ail know that living things
are distinguishable from ordinary non-living things by the
fact that they make some kind of response to changes in
the contact between themselves and their environment.
The "environment," of course, must be broadly inter-
preted. Biologically, it includes all things and forces that
m any way touch upon living matter. Not only bas every
plant and animal as a whole its environment, but every
part of it has an environment. The cells of an animal's
stomach, for example, have their environment in the blood
and lymph on one side, the contents of the stomach on the
other; in the energy of the nerves distributed to them; and
in the effects of heat and cold that penetrate them.
[991
INSECTS
The environmental conditions of the life of cells in a
complex animal are too complicated for an elemental
study; the elements of lire and its basic necessities are bet-
ter understood in a simple organism, or in a one-celled
animal; but for purposes of description, it is most con-
venient to speak of the properties of mere protoplasm.
AIl the vital needs of the most highly organized animal are
.pr.esent in any part of the protoplasmic substance of which
t ,s composed.
Protoplasm is a chemical substance, or group of sub-
stances, the structure of which is verv comp]ex but is main-
tained so long as there is no disturbance in the environ-
'°- ° BCIs BCIs BC]s
A ]3 C
FIG. 6. Diagram show]ng the relation of the germ ce]ls (GCIs) and the body
cells (BCIs) in successive generations
A fertilized germ cell of generation A forms the germ cells and by cells of B,
a fert]lized germ cell of B forms the germ cells and by cells of C, and so on.
The offspring C of B derives nothing from the body cells of the parent B, but
both offsp6ng C and parent B have a oemmon origin in a germ cell of A
metat. Let some least thing happen, however, such as a
change in the temperature, in the strength of the light, in
the weight of pressure, or in the chemical composition of
the surrounding medium, and the protoplasmic molecules,
in the presence ofoxygen, are likely to have the balance of
their constituent particles upset, whereupon they partly
decompose by the union of their less stable elements with
oxygen to form simpler and more permanent compounds.
The decomposition of the protoplasmic substances, like ail
processes of decomposition, liberates a certain amount of
energy that had been stored in the making of the molecule,
and this energy may manifest itselfin various ways. Ifit
[ I00]
WAYS AND MEANS OF LIVING
takes the form of a change of shape in the protoplasmic
mass, or movement, we sav the mass exhibits signs of life.
The state of being alive, however, is more truly shown if
the act can be repeated, for the essential property of living
matter is its power of reverting to its former chemical
composition, and its ability thus gained of again reacting
to another change in the environment. In restoring its
lost elements, it must get these elements anew from the
environment, for it can hot take them back from the sub-
stances that have been lost.
Here, expressed in its lowest terres, is the riddle of the
physical basis of lire and of the incentive to evolution in
the forms of lire. Not that these mvsteries are anv more
easily understood for being thus analyzed, but they are
more nearly comprehended. Being alive is maintaining the
power of repeating an action; it involves sensitivitv to
stimuli, the constant presence of free oxygen, elimination
of waste, and a supply of substances from which carbon,
hydrogen, nitrogen, and oxygen, or other necessary ele-
ments, are readilv available for replacement purposes.
Evolution results from the continual effort of living matter
to perform its lire processes in a more efficient manner, and
the different groups of living things are the result of the
different methods that lire has tried and found advan-
tageous for accolnplishing its ends. Living organisms are
machines that have become more and more complex in
structure, but always for doing the saine things.
If animals mav be compared with machines in their
physical mechanim, they are like them, too, in the fact
that they wear out and are at last beyond repair. But
here the simile ends, for when your car will no longer run,
you must go to the dealer and order a new one. Nature
provides continuous service by a much better scheme, for
each organism is responsible for its own successor. This
phase of lire, the replacement of individuals, opens another
subject involving ways and means, and it, likewise, can be
understood best in its simpler manifestations.
[ I0I ]
INSECTS
The facts of reproduction in animais are hot well ex-
pressed by our naine for them. Instead of "reproduc-
tion," it would be-truer to say "repeated production," for
individuals do hot literally reproduce themselves. Genera-
tions are serially related, hot each to the preceding; they
follow one another as do the buds along the twig of a tree,
Flç. 6 3. The external structure of an insect
The body of a grasshopper dissected showing the head (H), the thorax
and the abdomen (.4b). The head carries the eyes (E), the antennae (,llnt), and
the mouth parts, which include the labrum (Lrn), the mandibles (Md), the
maxillae {Mx), and the labium (Lb). The thorax consists of three segments
{I, 2,), the flrst separate and carrying the first legs (L,), the other two com-
bined and carrying the wings (1¢', 11"), and the second and third legs (L,, L.).
The abdomen consists of a series of segments; that of the grasshopper bas a
large tympanal organ (Tre), probably an ear, on each side of its base. The end
of the abdomen carries the external organs of reproduction and egg-laying
and buds on the saine twig are identical or nearly so, not
because one produces the next, but because ail are the
result of the saine generative forces in the twig. If the
spaces of the twig between the buds were shortened until
[ 102 ]
WAYS AND MEANS OF LIVING
one bud became contiguous with the one before, or became
enveloped by it, a relation would be established between
the two buds similar to that which exists between succes-
sive generations of lire forms. The so-called parent gen-
eration, in other words,
contains the germs of the
succeeding generation,
but it does not produce
them. Each generation
is simply the custodian
of the germ cells entrust-
ed to i t, and the "off-
spring" resembles the
parent, hot because it is
a chip off the parental
block, but because both
parent and offspring are
developed from the saine
line of germ cells.
Parents create the
conditions under wli, ch
the germ cells will de-
velop; they nourish and
protect them during the
period of their develop-
ment; and, when each
generation has served
the purpose of its ex-
istence, it sooner or
later dies. But the in-
dividuals produced from
F,c. 64. The leg of a young grasshopper,
showing the typical segmentation of an
insect's leg
The leg is supported on a pleural plate
(Pi) in the lateral wall of its segment.
The basal segment of the free part of the
leg is the coxa (Cx), then cornes a small
trochanter (Tf), next a long femur (F)
separated by the knee bend from the
tibia (Tb), and lastly the foot, consisting
of a sub-segmented tarsus (Tar), and a
pair of terminal claws (CI) with an ad-
hesive lobe hetween them
its germ cells do the saine
for another set of germ cells produced simultaneously
with themselves, and so on as long as the species
persists.
To express the facts of succession in each specific form of
animal, then, we should analyze each generation into germ
cells and an accompanying mass of protective cells which
[i]
INSECTS
forms a body, or soma, the so-called parent. Both the
body, or somatic, cells and the germ cells are formed from a
single primary cell, which, of course, is usually produced
by the union of two incomplete germ cells, a spermatozoon
and an egg. The primary germ cell divides, the daughter
cells divide, the cells of this division again divide, and the
division continues indefinitely until a mass of cells is pro-
duced. At a very early stage of division, however, two
groups of cells are set apart, one representing the germ
cells, the other the somatic cells. The former refrain from
further development at this time; the latter proceed to
build up the body of the parent. The relation of the
somatic cells to the germ cells may be represented diagram-
matically as in Figure 62, except that the usual dual par-
enrage and the union of germ cells is not expressed. The
sexual form of reproduction is not necessary with ail lower
animals, nor with ail generations of plants; in some insects
the eggs can develop without fertilization.
The fully-developed mass of somatic cells, whose real
function is that of a servant to the germ cells, has assumed
such an importance, as public servants are prone to do,
that we ordinarily think of it, the body, the active sentient
animal, as the essential thing. This attitude on our part
is natural, for we, ourselves, are highly organized masses
of somatic cells. From a cosmic standpoint, however, no
creature is important. Species of animais and plants exist
because they have found ways and means of living that
have allowed them to survive, but the physical universe
cares nothing about them--the sunshine is hOt ruade for
them, the winds are not tempered to suit their conven-
ience. Life must accept what it finds and make the best
of it, and the question of how best to further its own wel-
fare is the problem that conffonts every species.
The sciences of anatomy and physiology are a study of
the methods by which the soma, or body, bas contrived to
meet the requirements imposed upon it by the unchanging
laws of the physical universe. The methods adopted are as
[ o41
WAYS AND MEANS OF LIVING
numerous as the species of plants and animais that have
existed since lire began. A treatise on entomology, there-
fore, is an account of the ways and means of living that
insects have adopted and perfected in their somatic organ-
ization. Before discussing insects in particular, however,
we must understand a little more fully the principal con-
ditions of living that na-
ture places on ail forms of
lire.
As we have seen, lire is
a series of chemical re-
actions in a particular
kind of matter that can
carry on these reactions.
A "reaction" is an action;
and every act of living
matter involves a break-
ing down of some of the
substances in the proto-
plasm, the discharging of
the waste materials, and
the acquisition of new
materia]s to replace those
lost. The reaction is in-
herent in the physical or
chemical properties of
protoplasmic compounds
and depends upon the
substances with which
the protoplasm is sur-
rounded. It is the func-
Tb
.'Fb
:!ïllen
Fm. 6 5. Legs of a honeybee, showing
special modifications
A, outer surface of a hind leg, with a
pollen basket on the tibia (Tb) loaded
with pollen. B, a fore leg, showing the
antenna cleaner (a) between the tibia and
the tarsus, and the long, halry basal
segment of the tarsus (t Tar), which is
used as a brush for cleaning the body
tion of the creature's mechanism to see that the con-
ditions surrounding its living cells are right for the con-
tinuance of the cell reactlons. Each cell must be
provided with the means of eliminating waste material
and of restoring its lost material, since it can hot utilize
that which it has discarded.
[ o51
INSECTS
With the conditions of living granted, however, proto-
plasm is still only potentially alive, for there is yet required
a stimulus to set it into activity. The stimulus for lire
activities cornes from changes in the physical forms of
energy that surround or infringe upon the potentially
living substance; for, "live" marrer, like ail other marrer,
is subject to the law of inertia, which decrees that it must
remain at rest until motion is imparted to it by other
E
FIO. 66. The head and mouth parts of a grasshopper
A, facial view of the head, showing the positions of the antennae (dnt), the
large cornpound eyes (E), the slrnple eyes, or ocelli (O), the broad front lip,
or labrum (Lin) suspended from the cranium by the clypeus (Clp), and the
bases of the mandibles (Md, Md) closed behind the labrum
B, the rnouth parts separated from the head in relative positions, seen from
in front: Hphy, hypopharynx, or tongue, attached to base of labiurn; Lb, labiuml
Lin, labrum; Md, mandibles; Mx, maxillae
motion. A very small degree of stimulating energy, how-
ever, may result in the release of a great quantity of
stored energy.
The food of ail living matter must contain carbon,
hydrogen, nitrogen, and oxygen. The mechanism of
plants enables them to take these elements from com-
pounds dissolved in the water of the soli. Animais must
get them from other living things, or from the products of
[ Io6l
WAYS AND MEANS OF LIVING
living things. Therefore, animals principally have de-
veloped the power of movement; they have acquired grasp-
ing organs of some sort, a mouth, and an alimentary canal
for holding the food when once obtained.
In the insects, the locomotory function is subserved by
the legs and by the wings. Since all these organs, the three
pairs of legs and the two pairs of wings, are carried by the
thorax (Fig. 63, Th), this region of the body is distinctly
the locomotor center of the insect. The legs (Fig. 64) are
adapted, by modifications of structure in different species,
for walking, running, leaping, digging, climbing, swim-
ming, and for many varieties of each of these ways of pro-
gression, fitting each species for its particular mode of
living and of obtaining its food. The wings of insects are
important accesslons to their locomotory equipment,
since they greatly increase their means of getting about,
and thereby extend their range of feeding. The legs, fur-
thermore, are often modified in special ways to perform
some function accessory to feeding. The honeybee, as is
well known, has pollen-collecting brushes on its front legs
(Fig. 65 B), and pollen-carrying baskets on its hind legs
(A). The mantis, which captures other insects and eats
them alive, bas its front legs ruade over into those efficient
organs for grasping its prey and for holding the struggling
victim which have already been described (Fig. 46).
The principal organs bv which insects obtain and ma-
nipulate their food consist )f a set of appendages situated on
the head in the neighborhood of the mouth, which, in their
essential structure, are of the nature of the legs, for insects
have no jaws comparable with those of vertebrate animais.
The mouth appendages, or mouth parts as they are called,
are very different in form in the various groups of insects
that have different feeding habits, but in all cases they
consist of the saine fundamental pieces. Most important
is a pair of jawlike appendages, known as the mandibles
(Fig. 66 B, Md), placed at the sides of the mouth (A, Md),
where they swing sidewise and close upon each other
[ o7]
INSECTS
below the rnouth. Behind the rnandibles is a pair of
maxdlae lB, Mx) of more cornplicated forrn, fitted rather
for holding the food than for crushing it. Following the
rnaxillae is a large under lip, or labium I Lb), having the
Ant
- C Ht .- /I] An
 Vent
SoeGng C
6 7. Lençthwse se«t{on of • grshopper, showng the enrl
he pnn«p/ mtoEnl ornons, excep the resp{tory rachel system and
the organs of repruction
anus; .g.t, anoenna; Br, brain; Cr, op: Ht, heart: l.t, intestine:
Malpighian tubules: Mt. mouth: Oe, oesophagus; SoeGn, suesopheal
ganghon; ent, stomach (vent6culus); .VC, ventral nerve rd; , wings
structure of two rnaxi[lae united bv their inner rnargins.
A broad flap hangs downward befo're the rnouth to forrn
an upper lip, or labrum (Lm). Between the rnouth ap-
pendages and attached to the front of the Iabiurn there is a
large rnedian lobe of the lower head wall behind the rnouth,
known as the h.vpopharynx (Hphy).
Insects feed, sorne on solid foods, others on [iquids, and
their rnouth parts are rnodified accordingly. So it cornes
about that, according to their feeding habits, insects rnav
be separated into two groups, which, like the fox and the
stork, could hot feed either at the table of the other. Those
insects, such as the grasshoppers, the crickets, the beetles,
and the caterpillars, that bite off pieces of food tissue and
chew thern, have the rnandib[es and the other rnouth
parts of the type described above. Insects that partake
only of liquids, as do the plant lice, the cicadas, the rnoths,
the butterflies, the rnosquitoes and other flies, bave the
[ IO8]
WAYS AND MEANS OF I_.IVING
mouth parts fitted for sucking, or for piercing and sucking.
Some of the sucking types of mouth parts will be described
in other chapters (Figs. , 63, 83) , but it will be seen
that ail are merelv adaptations of form based on the ordi-
narv biting type of mouth appendages. The fossil records
of t'he history of insects show that the sucking insects are
the more recent products of evolution, since ail the earlier
kinds of insects, the cockroaches and their kin, have
typical biting mouth parts.
The principal thing to observe concerning the organs of
feeding, in a studv of the physiological aspect of anatomy,
is that thev serve in ail cases to pass the natural food
materials from the outside of the animal into the alimen-
tarv canal, and to live them whatever crushing or masti-
canon is necessarv. It is within the alimentary canal,
therefore, that the next steps toward the final nutrition
of the animal take place.
The a]imentarv cana] of most insects is a simple tube
(Fig. 68), extend'ing either straight through the body, or
FI{I. 68. The alimentary canal of a grasshopper
IInt, anterior intestine; dn, anus; Cr, crop; GC, gastric caeca, pouches of the
stomach; Hphy, hypopharynx (tongue); Lb, base of labium; Mal, Malpighian
tubules; Mlnt, raid-intestine; llth, mouth; Oe, oesophagus; Rect, hind intestine
(rectum); SIGI, salivary glands opening by their united ducts at base of hypo-
pharynx; I/ent, ventriculus (stomach)
making only a few turns or loops in its course. It con-
sists of three principal parts, of which the middle part is
the true stomach, or ventriculus (Fent) as it is called by
insect anatomists. The first part of the tube includes a
[ 'o91
INSECTS
pharynx irnrnediately behind the rnouth, followed by a
narrower, tubular oesophagus (Oe), after which cornes a sac-
like enlargernent, or crop (Cr), in which the food is tern-
porarily stored, and finally an antecharnber to the stornach,
narned the proventriculus. The third part of the alimen-
tary canal, connecting the stomach with the anal opening,
is the intestine, usually cornposed of a narrow anterior
part, and a wide posterior part, or rectum (Rect). Muscle
layers surrounding the entire alirnentary tube cause the
food to be swallowed and to be passed along from one
section to the next toward the rear exit.
With the taking of the food into the alirnentary canal,
the/natter of nutrition is by no rneans accornplished, for
the animal is still confronted with the problern of getting
the nutrient rnaterials into the inside of its body, where
alone they can be used. The alirnentary tube bas no
openings anywhere along its course into the body cavity.
Whatever food substances the tissues of the animal receive,
therefore, rnust be taken through the walls of the tube in
which they are inclosed, alad this transposition is accorn-
plished by dissolving thern in a liquid. Most of the nutri-
ent rnaterials in the raw food rnatter, however, are hot
soluble in ordinary liquids; they rnusr be changed chern-
ically into a forrn that will dissolve. The process of get-
ring the nutrient parts of the raw foodstuff into solution
constitutes digestion.
The digestive liquids in insects are furnished rnostly
by the stornach walls or the walls of tubular glands that
open into the stornach, but the secretion of a pair of large
glands, called the salivarv glands (Fig. 68, SIGI), which
open between the rnouth parts, perhaps bas m sorne
cases a digestive action on the food as it is taken into the
mouth.
Digestion is a purely chemical process, but it must be
a rapid one. Consequently the digestive juices contain
hot only substances that will transforrn the food rnaterials
into soluble cornpounds, but other substances that will
[ II0]
WAYS AND MEANS OF LIVING
speed up these reactions, for otherwise the animal would
starve on a full stomach by reason of the slowness of its
gastric service. The quickening substances of the diges-
tive fluids are called enzymes, and each kind of enzyme
acts on only one class of food material. An animal's prac-
tical digestive powers, therefore, depend entirely upon
the specific enzymes its digestive liquids contain. Lacking
this or that enzyme it can hot digest the things that depend
upon it, and usually its instincts are correlated with its
enzymes so that it does hot fill its stomach with food it can
hot digest. A few analyses of the digestive liquids of in-
sects have been ruade, enough to show that their digestive
processes depend upon the presence of the saine enzymes as
those of other animais, including man.
The grosser digestive substances, in cooperation with
the'enzymes, soon change all the parts of the food ma-
terials in the stomach that the animal needs for its suste-
nance into soluble compounds which are dissolved in the
liquid part of the digestive secretions. Thus is produced
a rich, nutrient juice within the alimentary canal which
can be absorbed through the walls of the stomach and intes-
tine and can so enter the closed cavity of the body. The
next problem is that of distribution, for still the food ma-
terials must reach the individual cells of the tissues that
compose the animal.
The insect's way of feeding, of digesting its food, and of
absorbing it is hot essentially different from that of the
higher animais, including ourselves, for alimentation is a
very old and fundamental function of ail animais. Its
means of distributing the digested food within its body,
however, is quite different from that of vertebrates. The
absorbed pabulum, instead of being received into a set of
lymphatic vessels and from these sent into blood-filled
tubes to be pumped to ail parts of the organism, goes
directly from the alimentary walls into the general body
cavity, which is filled with a liquid that bathes the inner
surfaces of ail the body tissues. This body liquid is called
[ III ]
INSECTS
the "blood" of the insect, but it is a colorless or slightly
yellow-tinted lymph. It is kept in motion, however, by a
pulsating vessel, or heart, lying
Fro. 69. Diagram of the
typical structure of an insect's
heart and supporting dia-
phragm, with the course of the
circulating blood marked by
,o, aorta, or anterior tubular
part of the heart without
lateral openings; Dpk, mem-
branous diaphragm; Ht, ante-
rior three chambers of the
heart, which usually extends
to the posterior end of the
body; Md, muscles of dia-
phragm, the fibers spreading
from the body wall to the
heart; Ost, ostium, or oneofthe
lateral openings into the heart
chambers
in the dorsal part of the body;
and by this means the food, now
dissolved ira the body liquid, is
carried into the spaces between
the various organs, where the
cells of the latter can have access
to it.
The heart of the insect is a
slender tube suspended along the
midline of the back close to the
dorsal wall of the bodv (Fig. 67,
1/t). It has intake apertures
along its sides I Vig. 69, Ost), and
its anterior end opens into the
body cavitv. It pulsates for-
ward, by means of muscle fibers
in its walls, thereby sucking the
blood in through the lateral
openings and discharging it by
way of the front exit. An im-
perfect circulation of the blood
is thus established through the
spaces between the organs of the
bodv cavity, sufficient for the
purposes of so small an animal as
ara insect.
The final act of nutrition cornes
now when the blood, charged
with the nutrient materials ab-
sorbed from the digested food
in the alimentarv canal, brings
these materials into contact with
the inner tissues. The tissue
cells, by the inherent power of
[ 112]
WAYS AND MEANS OF LIVING
ail living rnatter (which depends on the laws of osrnosis
and on chernical affinity), take for thernselves whatever
they need frorn the menu offered bv the blood, and with
this rnatter they build up their own substance. It is
evident, therefore, that the blood rnust contain a suffi-
cient quantity and varietv of dietary elernents to satisfy
ail possible cell appetites; that the stornach's walls and
their associated glands must furnish the enzyrnes appro-
priate for rnaking the necessary elernents available frorn
the raw food rnatter in the stornach; and, finally, that it
rnust be a part of the instincts of each animal species to
consume such native foodstuffs of its environment as will
supply every varietv of nourishing elernents that the cells
dernand.
As we have seen, the dernand for food cornes frorn the
loss of rnaterials that are decornposed in the tissues during
cell activitv. Better stated, perhaps, the chernical break-
down with[n the cell is the cause of the cell activity, or is
the cell activity itself. The way in which the activity is
expressed does hot rnatter; whether bv the contraction of a
muscle cell, the secretion of a gland cell, the generation of
nerve energy bv a nerve cell, or just the rninirnurn activity
that rnaintains'life, the result is the saine always--the loss
of certain substances. But, as with rnost chernical reduc-
tion processes, the protoplasrnic activity depends upon the
presence of available oxygen; for the decornposition of the
unstable substances of the protoplasrn is the result of the
affinity of sorne of their elernents for oxygen. Conse-
quently, when the stimulus for action cornes over a nerve
frorn a nerve center, a sudden reorganization takes place
between these protoplasrnic elernents and the oxygen
atorns which results in the formation of water, carbon
dioxide, and various stable nitrogenous cornpounds.
The substances discarded as a result of the cell activi-
ties are waste products, and nlust be elirninated frorn the
organisrn for their presence would clog the further activitv
of the cells or would be poisonous to thern. The anirnai,
[3]
INSECTS
therefore, must have, in addition toits mechanisms for
bringing food and oxygen to the cells, a means for the re-
moral of wastes.
The supplying of oxygen and the removing of carbon
dioxide and some of the excess water are accomplished by
respiration. Respiration is primarily the exchange of gases
between the cells of the body and the outside air. If an
animal is suflîciently small and soft-skinned, the gas ex-
change can be made directly by diffusion through the skin.
Larger animais, however, must bave a device for conveying
air into the body where the tissues wil bave closer access
toit. It will be evident, then, that there is hot neces-
sarily only one way of accomplishing the purposes of
respiration.
Vertebrate animais inhale air into a sac or pair of sacs,
called the lungs, through the very thin walls of which the
oxygen and carbon dioxide can go into and out of the
blood respectively. The blood contains a special oxygen
carrier in the red matter, hemogobin, of its red corpuscles,
by means of which the oxygen taken in from the air is
transported to the tissues. The carbon dioxide is carried
from the tissues partly by the hemoglobin, and partly
dissolved in the blood liquid.
Insects bave no lungs, nor bave they hemoglobin in their
blood, which, as we have seen, is merely the liquid that fills
the spaces of the body cavity between the organs, lnsects
bave adopted and perfected a method of getting air dis-
tributed through their bodies quite different from that of
the vertebrates. They bave a system of air tubes, called
tracheae (Fig. 7o), opening from the exterior by small
breathing pores, or spiracles (Sp), along the sides of the
body, and branching minutely within the body to ail parts
of the tissues. By this means the air is conveyed directly
to the parts where respiration takes place. There are
usually in insects ten pairs of spiracles, two on the sides of
the thorax, and eight on the abdomen. The spiracles
communicate with a pair of large tracheal trunks lying
114]
WAYS AND MEANS OF LIVING
along the sides of the body (Fig. 7o), and from these
trunks are iven off branches into each body segment and
into the head, which go to the alimentary canal, the heart,
the nervous system, the muscles, and to ail the other
organs, where they break up into finer branches that
terminate in minute end tubes going
practically to every cell of the body.
Many insects breathe by regular
movements of expansion and contrac-
tion of the under surface of the abdo-
men, but experimenters have hot yet
agreed as to whether the air goes in
and out of the saine spiracles or
whether it enters one set and is ex-
pelled through another. It is probable
that the fresh air goes into the smaller
tracheal branches principally by gas
diffusion, for some insects make no
perceptible respiratory movements.
The actual exchange of oxygen from
the air and carbon dioxide from the
tissues takes place through the rhin
walls of the minute end tubes of the
tracheae. Since these tubes lie in im-
mediate contact with the cell surfaces
the gases do not have to go far in
order to reach their destinations, and
the insect has little need of an oxygen
carrier in its blood--its whole body,
practically, is a lung. And yet some
investigations have ruade it appear
likely that the insect blood does con-
tain an oxygen carrier that functions
in a manner similar to that of the
hemoglobin of vertebrate blood,
though the importance of oxygen
transportation in insect physiology has
[51
Fe. 7 . Respirator l'
system of a eaterpillar.
The external breathing
apertures, or spiracles
(S/, S/), along the
sides of the body open
into lateral tracheal
trunks (a, a), which
are connected crosswise
by transverse tubes
(b, b) and give off mi-
nutely branching tra-
cheae into ail parts of
the head (H) and body
INSECTS
hOt been determined. In any case, the tracheal method
of respiration must be a very efficient one; for, consider-
ing the activity of insects, especially the rate at which the
wing muscles act during flight, the consumption of oxygen
must at times be pretty high.
The activity of insects depends very much, as every one
knows, upon the temperature. We bave ail observed how
the bouse flies disappear upon the first cold snap in the rail
and then surprise us by showing up again when the weather
turns warm, just after we bave taken down the screens.
AIl insects depend largely upon external warmth for the
heat necessary to maintain cellu[ar activity. While their
movements produce heat, they bave no means of con-
serving this heat in their bodies, as bave "warm-blooded"
animais. That insects radiate heat, however, is very
evident from the high temperature that bees can maintain
in their hives during winter by motion of the wings. Ail
insects exhale much water vapor from their spiracles, an-
other evidence of the production of heat in their bodies.
The solid matter thrown off from the cells in activity is
discharged into the blood. These waste materials, which
are mostly compounds of nitrogen in the form of salts,
must then be removed from the b]ood, for their accumula-
tion in the body would be injurious to the tissues. In
vertebrate animais, the nitrogenous wastes are eliminated
by the kidneys. Insects bave a set of tubes, comparable
with the kidneys in function, which open into the intestine
at the junction of the latter with the stomach (Fig. 68,
Mal), and which are named, after their discoverer, the
Malpighian tubule«. These tubes extend through the prin-
cipal spaces of the body cavity, where they are looped
and tangled like threads about the other organs and are
continually bathed in the blood. The cells of the tube
walls pick out the nitrogenous wastes from the blood and
discharge them into the intestine, whence they are passed
to the exterior with the undigested food refuse.
We thus see that the inside of an insect is hOt an unor-
[116]
WAYS AND MEANS OF LIVING
ganized mass of pulp, as believed by those people whose
education in such naatters cornes principally from under-
foot. The physical unity of ail fornas of lire makes it neces-
sary that every creature naust perforna the sanae vital
functions. The insects have, in naany respects, adopted
their own wavs of accomplishing these functions, but, as
already pointC out, the naeans of doing a thing does hot
count with nature so long as the end results are attained.
The essential conditions are the supply of necessities and
the removal of wastes.
The body of a conaplex aninaal naay be likened to a great
factory, in which the individual workers are represented by
the cells, and groups of workers by the organs. That the
factorv naay accornplish its purpose, the activities of each
worker naust be coordinated with those of all the other
workers by orders fron a directing office. Just so, the ac-
tivities of the cells and organs of the animal must be con-
trolled and coordinated; and the directing office of the
aninaal organization is the central nervous systena. The
work of almost every cell in the body is ordered and con-
trolled by a "nerve inapulse" sent toit over a nerve fiber
frona a nerve center.
The inner structure of the nervous tissues and the work-
ing mechanisna of the nerve centers are essentially alike in
ail animals, but the form and arrangenaent of the nerve
tissue masses and the distribution of the nerve fibers naay
differ nhuch according to the plan of the general body or-
ganization. The insects, instead of following the verte-
brate plan of having the central nerve cord along the back
inclosed in a bonv sheath, bave round it just as well for
their purposes to lave the principal nerve cord lying free in
the lower part of the bodv (Fig. 67, I'.VC). In the head
there is a brain (Figs. 7, 7 -, Br) situated above the
oesophagus (Fig. 67, Oe), but it is connected by a pair of
cords with another nerve mass below the pharynx in the
lower part of the head (SoeGlg). Frona this nerve naass
another pair of nerve cords goes to a third nerve mass
[7]
INSECTS
D o
Fro. 7 . The nervous system of the head of a grass-
hopper, as seen by removal of the facial wall
.4ntNv, antennal nerve; 1Br, gBr,3Br, the three parts
of the brain; CoeCon, circumoesophageal connectives;
3Corn, suboesophageal commissure of the third Iobes
of the brain; FrGng, frontal ganglion FrCon, frontal
ganglion connective with the brain; LbNv, labial
nerve; LraNv, labral nerve; MdNv mandibular nerve;
MxNv, maxillary nerve; O, simple eye; OpL, optic
lobe connected with the brain; RNv, recurrent nerve;
8oeGng, suboesophageal ganglion
lying against the
lower wall of the
first body seg-
ment (Fig. 7,
Gng ), which is
likewise connect-
ed with a fourth
mass in the sec-
ondsegment,and
so on. The cen-
tral nervous sys-
tem of the insect
thus consists of
a series of small
nerve masses
united by double
nerve cords. The
nerve masses are
known as gan-
glia (Gng), and
the uniting cords
are called the
connectives (Fig.
7, Con). Typi-
cally there is a
ganglion for each
of the first
eleven body seg-
ments, besides
the brain and
the lower gan-
glioia of the head.
The brain of an insect (Fig. 7 ) has a highly complex
internal structure, but it is a less important controlling
center than is the brain of a vertebrate animal. The other
ganglia have much independence of function, each giving
the stimuli for movements of its own segment. For this
WAYS AND MEANS OF LIVING
reason, the head of an insect may be cut off and the rest
of the creature may still be able to walk and to do various
other things until it dies of starvation. Similarly, with
some species, the abdomen may be severed and the insect
will still eat, though the food runs out of the cut end of the
alimentary canal. The detached abdomen may lay eggs,
if properly stimulated. Though the insect thus appears to
be largely a creature of automatic regulations, acts are hOt
initiated without the brain, and full coordination of the
functions is possible only when the entire nervous system
is intact.
The active elements of the nerve centers are nerve cells;
the nerve fibers are merely conducting threads extended
from the cells. If the nerve force that stimulates the other
kinds of cells into activity cornes from nerve cells, the
question then arises as to whence cornes the primary
stimulus that activates the nerve cells. We must discard
the old idea that nerve cells act automatically; being mat-
ter, they are subject to the laws of matter--they are inert
until compelled fo act. The stimulus of the nerve cells
cornes from something outside of them, either from the
environmental forces of the external world or from sub-
stances formed by other cells within the body.
Nothing is known definitely of the internal stimuli of
insects, but there can be no doubt that substances are
formed by the physiological activiries of the insect tissues,
similar to the horrnones, or secretions of the ductless glands
of other animais, that control action in other organs either
directly or through the nervous system. Thus, some in-
ternal condition must prompt the insect to feed when its
stomach is empty, and the entrance of food into its pharynx
must stimulate the alimentary glands to prepare the diges-
tive juices. Probably a secretion from the reproductive
organs of the female, when the eggs are ripe in the ovaries,
gives the stimulus for mating, and later sets into motion
the reflexes that govern the laying of the eggs. The cater-
pillar spins its cocoon at the proper rime for doing so; the
[I191
INSECTS
Store
Gris'2
l+Ii+lll
V
GnçVl - - ..... VI
FIG. 7 2. The general nervous system of a grass-
hopper, as seen from above
/lnt, antenna; /o, aorta;/i'r, brain; Cer, cercus; E,
compound eye; Gngl, ganglion of prothorax;
Gng2, ganglion of mesothorax; Gng3+I+II+III,
compound ganglion of metathorax, comprising
the ganglia belonging to the metathorax and the
first three abdominal segments; Gngll/oEngl/llI,
ganglia of the fourth to eighth abdominal seg-
ments; O, ocelli; Proc, proctodeum, or posterior
part of alimentary canal; .ça, suranal plate;
.çeglI--X, second to tenth segments of abdomen;
.çoeGng, suboesophageal ganglion; .çtom, stomo-
deum, or anterior part of alimcntary canal
stimulus, most like-
ly, comes from the
products of physio-
logical changes be-
ginning to take place
in the body that will
soon result in the
transformation of
the caterpillar into
a chrysalis, a stage
when the insect
needs the protection
of a cocoon. These
activities of insects
we call instincts, but
the term is simply a
cover for our ignor-
ance of the processes
that cause them.
External stimuli
are things of the
outer environment
that affect the living
organism. They in-
clude matter, elec-
tromagnetic energy,
and gravity; but the
known stimuli do
hot comprise ail the
activities of marrer
or of the "ether."
The common stimuli
are: pressure of
solids, liquids, and
gases; humidity;
chemical qualities
(odors and tastes);
[ 120]
WAYS AND MEANS OF LIVING
sound, heat, light, and gravity. Most of these things stim-
ulate the nerve centers indirectly through nerves connected
with the skin or with specialized parts of the skin called
sense organs. An animal can respond, therefore, onlv to
those stimuli, or to the degrees of a particular stimulus, to
which it is sensitive. If, for example, an animal has no re-
ceptive apparatus for sound waves, it will hot be affected
by sound; if it is not sensitized to certain wave lengths of
light, the corresponding colors will not stimulate it. There
are few kiMs of natural activities in the environment that
animais do not perceive; but even our own perceptive
powers fMI far short of registering ail the degrees of any
activity that are known to exist and which the physicist
tan measure.
nsects respond to most of the kinds of stimuli that we
perceive bv out senses; but if we say that they see, hear,
smell, taste, or touch we make the implication that insects
have COllSCiOUSlleSS. t is most likely that their reactions
to external stimuli are for the most part performed un-
consciously, and that their behavior under the effect of a
stimulus is an automatic action entirely comparable to
out reflex actions. Behavioristic acts that result from
reflexes the biologist calls tropim. Coordinated groups
of tropisms constitute an instinct, though, as we have
seen, an instinct may depend also on internal stimuli. It
can hot be said that consciousness does hOt play a small
part in determining the activities of some insects, es-
pecially of those species in which memory, i.e., stored
impressions, appears to give a power of choice between
different conditions presented. The subject of insect
psychology, however, ls too intricate to be discussed
here.
The phases of lire thus far described, the complexity
of physical organization, the response to stimuli, the
phenomena of consciousness from their lowest to their
highest manifestations, ail pertain to the soma. Yet»
somehow, the plan of the edifice is carried along in the
[121]
INSECTS
germ cells, and by them the whole somatic structure is
rebuilt with but little change of detail from generation to
generation. This phase of lire activity is still a mystery
to us, for no attempted explanation seems adequate to
account for the organizing power resident in the germ
cells that accomplishes the familiar facts of repeated
k-X DO
A B
Fç. 73- Dirams f the internal organ of reproduction in insects
A, the female otgans, mprising a pair f aries (Or), ea«h «ompsed f 
group f g tubuls (oe), a pair f ovidu«ts (DOv),and a median ourlet tube,r
vina (g), ith usually a pair of «olleterial glands (CIÇI) dis«haing into
the agina, and a sperm roEeptade» r spermatha (p), opening from the
upr surface of the latter
B, the maie oans, comprising a pair of restes (Tes) coms of spermatic
tubules, a pair of srm ducts, or vasa deferentia (D), a pair of srm vesicles
(gS), and an outlet tube, or ductus ejaculatorius (DES, with usually a pair of
mucous glands (MGI) discharging into the ducts of the sperm vesicles
development which we call repruction._ When we can
explain the repetition of buds along the twig, we may
bave a key to the secret of the germ cellsand possibly
to that of organic evolution.
The organs that house the germ cells in the mature
insect consist of a pair of ovaries in the female (Fig. 73 A,
Or) in which the eggs mature, and of a pair of testes in the
[l
WAYS AND MEANS OF LIVING
maie (B, Tes) in which the spermatozoa reach their com-
plete growth. Appropriate ducts connect the ovaries or
the testes with the exterior near the rear end of the body.
The female usually has a sac connected with the egg duct
(A, Spm) in which the sperm, received at mating, are
stored until the eggs are ready to be laid, when they are
VIII IX X Cet"
I I /
.-A t I
Fxc. 74- The oviposltor of a long-horned grasshopper, a member of the katydid
family, showing the typical structure of the egg-laying organ of female insects
A, the ovipos'itor (Ovp) in natural condition, projecting from near the posterior
end of the body
B, the parts of the ovlpositor separated, showing the six component pieces,
two arising from theeighth abdominal segment (FIII), and four from the nlnth
(IX). /ln, anus; Cet, cerci; IX, ninth abdominal segment; Ovp, ovipositor; FgO,
vaginal opening; FIH, eighth abdominal segment; X» tenth abdominal segment
extruded upon the latter and bring about fertilization.
The egg cells ordinarily are ail alike, but the spermatozoa
are of two kinds; and according to the kind of sperm re-
ceived by any particular egg, the future individual will be
maie or female.
[3]
INSECTS
The germ cells accompanying each new soma undergo a
series of transformations within the parent body before
thev themselves are capable of accomplishing their pur-
pose. Thev multiply enornaously. With some animais,
only a few of them ever produce new members of the race;
but with insects, whose motto is "safety in numbers,"
each species produces every season a great abundance of
new individuals, to the end that the many forces arrayed
against them mav hot bring about their extermination.
The world seems full of forces oppos.ed to organized lire.
But the truth is, ail organization s an opposition to
established forces. The reason that the forms of life now
existing have held their places in nature is that they have
found and perfected wavs and means of opposing, for a
time, the forces that tend to the dissipation of energy.
i.ife is a revolt against inertia. Those species that have
died out are extinct, either because they came to the end
of their resources, or because they became so inflexibly
adapted to a certain kind-of lire that thev were unable to
meet the emergency of a change ira the conditions that
ruade this lire possible. Eflïciency ira the ordinary means
of living, rather than specialization for a particular way of
living, appears to be the best guarantee of continued
existence.
[ -4]
CHAPTER V
TERMITES
lr was the custom, hot long ago, to teach the inexperienced
that the will can achieve whatever ambition mav desire.
"Believe that vou can, and vou can, ifonly you work hard
enough"; this was the subjéct of manv a maxim very en-
couraging, no doubt, to the young adventurer, but just as
likely to lead to a bench in I.'nion Square as to a Fifth
Avenue studio or a seat in the Stock Exchange.
Now it is the fashion to give us mental tests and voca-
tional suggestions, and we are admonished that it is no
use trying to be one thing if nature bas ruade us for some-
thing else. This is sound advice; the onlv trouble is the
difficultv of being able to detect at an eariy age the char-
acters tat are to distingtfish a pl.umber from a doctor, a
cook from an actress, or a financier from an entomologist.
Of course, there really are differences between ail classes
of people from the time they are born, and a fine thing
it would be if we could know in our vouth just what each
one of us is designed to become, in the present chap-
ter we are to learn that certain insects appear to have
achieved this very thing.
The termites are social insects; consequently in study-
ing them, we shall be confronted with questions of con-
duct. Therefore, it will be well at the outset to look
somewhat into the subject of morality; hot, be assured,
to learn any of its irksome precepts, but to discover its
biological significance.
Right and wrong, some people think, are general ab-
stractions that exist in the very nature of things. They
INSECTS
are, on the contrary, specific attributes that are condi-
tioned by circumstances. An act that is right is one in
accord with the nature of the creature performing it; that
which is.wrong is a contrary act. Hence, what is right for
one specles of animal may be wrong for another, and the
reverse.
The conduct of adult human individuals, according to
human standards of right and wrong, we call morals; the
similar conduct of other animais is a part of what biolo-
gists call behavior. But we unconsciously recognize some-
thing in common between morals and behavior when we
speak of the acts of a child, which we call his behavior
rather than his morals.
Behavior, in other
words, we regard as in-
volving less of personal
responsibility than mo-
rality. Hence we say
Fo. 75- A common that animais and chil-
speci«s of termite of dren behave, but that
eastern North America
inhabiting dead wood, adult human beings con-
Reticulitermes flaipes, sciously do right or
A, B, winged forms, wrong. Yet, the two
C, a soldier. D, workers -
modes of action accom-
plish similar results: if the child behaves
properly, his actions are right; if the
adu]t bas a proper]y deve]oped moral
sense, he too does the right thing, or at
least he terrains from doing the wrong
thing unless misguided by circumstances
or by his reasoning.
Animais other than the human, it
appears, generally do what is right from their standpoint;
but their actions, we say, are instinctive. Some will insist
that the terres "right" and "wrong" can bave no appli-
cation to them. Substitute then, if you please, the
expression "appropriate or non-approprate to the ani-
[IŒEE6]
TERMITES
mal's way of living." And still, our morality will analyze
into the saine two elements; our acts are right or wrong
according as they are appropriate or non-appropriate to
out way of living.
The difference between human actions and those of
other animais is hot essentially in the acts themselves, but
in the methods by which they are brought about. Animais
are controlled by instincts, mostly; man is controlled by a
conscious feeling that he should do this or that--"con-
science," we call it--and his specific actions are the result
of his reasoning or teaching as to what is right and what is
wrong, excepting, of course, the acts of perverted indi-
viduals who lack either a functional conscience or a well-
adjusted power of reason, or of individuals in whom the
instincts of an earlier way of living are still strong. The
general truth is clear, however, that in behavior, as in
physiology, there is hot just one way of arriving at a
common result, and that nature may employ quite dif-
ferent means for determining and activating conduct in
her creatures.
Since right and wrong, then, are hOt abstract prop-
erties, but are terres expressing fitness or non-fitness,
judged according to circumstances, or an animal's way of
living, it is evident that the quality of actions will differ
much according to how a species lires. Particularly
will there be a difference in the necessary behavior of
species that lire as individuals and of those that lire as
groups of individuals. In other words, that which may
be right for an individualistic species may be wrong for
a communal species; for, with the latter, the group re-
places the individual, and relations are now established
within the group, or pertaining to the group as a whole,
that before applied to the individual, while relations that
formerly existed between individuals become now rela-
tions between groups.
The mority of animais live as individuals, each
wandering here and there, wherever its fancy leads or
[ IOE7]
I NSECTS
Fro. 7 6 . Termite work in a piece of
wood. Tunnels following the grain are
ruade by species ofRetieulitermes, the coin-
mon underground termites-of the eastern
United States
wherever the food supply attracts it, recognizing no ties
or responsibilities to others of its species and contending
witb its fellows, often in dead]y combat, for whatever
advantage it can gain. A few animals are communistic
or social in their mode
of lire; notab]y so are
man and certain insects.
Tbe best-known exam-
pies of social insects are
the ants and some of the
bees and wasps. The
termites, however, con-
stitute anotber group of
social insects of no less
interest than the ants
and bees, but whose hab-
its bave hot been so long
observed.
More fami]iar]y to
some peop]e, termites are
known as "white ants."
But since they are hot
ants, nor a]ways white
or even pale in color, we
should discard this mis-
leading and unjustifiable
appellation and learn to
know the termites by the
name under which thev
are universally known to
entomologists.
If you split open an
old board that has been
lying almost anywhere
on the ground for some
time, or if, wben out in
tbe woods, you cut into
[
TERMITES
a dead stump or a log, you are more than likely to find
it tunneled ail through with small tubular galleries running
with the grain of the wood, but everywhere connected
crosswise bv small openings or short passages. Within
the exposed[ galleries there will be seen numerous small,
pale, wingless insects running here and there in an effort
to conceal themselves. These insects are termites.
They are the miners or the descendants of miners that
have excavated the tunnels in which they live. Not all
of the galleries in the nest are open runways, many of
them being packed solidly with small pellets of refuse.
If the termites confined themselves to useless wood,
they would be known onlv as interesting insects; but
since they often extend the[r operations into fence posts,
telegraph poles, the woodwork of bouses, and even into
furniture, they have placed themselves among the de-
structive insects and bave acquired an important place
in the pages of economic entomology. Stored papers,
books, cloth, and leather are hot exempt from their at-
tack. In the United States it hot infrequently happens
that the flooring or other wooden parts of buildings must
be replaced, owing to the unsuspected work of termites;
and piled lumber is especially liable to invasion by these
insidious insects. But in tropical countries the termites
are far more numerous than in temperate regions, and
are vastly more destructive than they are with us. Their
seclusive habits make the termites a particularly vexa-
tious pest, because they bave usually accomplished an
irreparable amount of damage before their presence is
known or suspected. The economic entomologist study-
ing termites gives most of his attention, therefore, to
devising methods of preventing the access of the insects
to ail wooden structures that they might destroy.
The work of termites and the ways and means that
bave been contrived to prevent their ravages bave been
described in many agricultural publications, and the
reader whose tastes are purely practical is referred to
[ xoE9]
INSECTS
the latter for information. Here we will look more closely
into the lives of the termites themselves to see what
lessons we may learn from these creatures that have
adopted something of our own way of living.
When a termite nest is broken open, it does hot appear
that there is much of an organization among the inseets
Fro. 77- Reticulitermesflavipes (much enlarged)
A, a mature worker. B, a mature soldier. C, a young termite.
D, an immature winged (orm
hurrying to take refuge in the recesses of the galleries,
but neither when a bomb strikes one of out own dwellings
is there probably much evidence of order within. The
most casual observation of the termites, however, will
[3o]
TERM ITES
show something of interest concerning them. In the
first place, it is to be seen that not ail the members of the
colony are alike. Some, usuallv the greater number, are
small, ordinary, soft-bodied, wingless insects with rounded
heads and inconspicuous jaws (Figs. 75 D, 77 A). Others,
less numerous, have bodies like the first, and are also
wingless, but their heads are relatively of enormous size
and support a pair of large, strong jaws projecting out
in front (Figs. 75 C, 77 B). The individuals of the latter
kind are known as soldiers, and the naine is hot entirely
fanciful, since fighting is hot necessarily the everyday
occupation of one in military service. The others, the
small-headed individuals, are called z'orkers, and they
earn their title literally, for, even with their small jaws,
they do most of the work of excavating the tunnels, and
they perform whatever other labors are to be done within
the nest.
Both the workers and the soldiers are males and females,
but so far as reproductive powers go, they may be called
"neuters," slnce their reproductive organs never mature
and they take no part in the replenishment of the colony.
In most species of termites the workers and the soldiers
are blind, having no eyes or but rudiments of eyes. In
a few of the more primitive termite genera, workers are
absent, and in the higher genera they may be of two
types of structure. The large jaws of the soldiers (Fig.
78 A) are weapons of defense in some species, and the
soldiers are said to present themselves at any break in the
walls of the nest ready to defend the colony against in-
vasion. In some speeies, the soldiers have a long tubular
horn projecting forward from the face (Fig. 78 B), through
which opens the duct of a gland that emits a sticky,
semiliquid substance. This glue is discharged upon an
attacking enemy, who is generally an ant, and so thor-
oughly gums him up that he is rendered helpless--a
means of combat yet to be adopted in human warfare.
The facial gland is developed to such efficiency as a
[131]
INSECTS
weapon in manv species of one termite family that the
soldiers of these species have no need of jaws, and their
mandibles have become rudimentary. In ail cases, the
militarv specialization of the soldiers has rendered them
incapable of feeding themselves, and they must depend
on the workers for food.
In addition to the soldiers and the workers, there
would probably be seen within the termite nest, at cer-
//lVid
F. 7 8. Two forms of defensive organs of termite soldler
A, head of soldier of Termopsis, showing the highly developed mandibles (Md),
and the great muscles within the head (admd) that close them. B, a soldier of
Nasutitermes (from Banks and Snyder); the head has small jaws but is provided
with a long snoutlike horn through which i ejected a gummy liquid used for
defense
tain seasons of the year, many individuals (Fig. 77 D)
that have small wing rudiments on their thoracic seg-
ments. As the season advances, the wing pads of these
individuals increase in length, until at last they become
long, gauzy, fully-developed wings extending much beyond
the tip of the body (Figs. 75 A, B, 79)- The color of the
body also becomes darker, and finally blackish when the
insects are mature. Then, on some particular day, the
l J32 ]
TERMITES
whole winged brood issues from the nest in a great swarm.
Since insects are normally winged creatures, itis evident
that these flying termites represent the perfect forms of
the termite colony--they are, in fact, the sexually mature
males and females.
The several forms of individuals in the termite com-
munity are known as castes.
An intensive search through the galleries 9f a termite
nest might reveal, besides workers, soldiers, and the
members of the winged brood in various stages of devel-
opinent, a few individuals of still different kinds. These
have heads like the winged forms, but rather larger bodies;
some have short wing rudiments (Fig. 8o), others have
none; and finally there are two individuals, a maie and
a femme, bearing wing stubs from which, evidently,
fully-formed wings have been broken off. The mme of
this last pair is just an ordinary-looking, though dark-
bodied termite
(Fig. 82 A); but
the female is dis-
tinguished from
ail the other mem-
bers of the colony
bv the great size
oi her abdomen
(B).
Through the in-
vestigations of
entomologists it is
known that the
Fzç. 79- Adult winged caste of Reticulitermes tibialis,
short-winged, and wings shown on oneBanksSideandOfSnyder)the body only. (From
wingless individu-
als of this group comprise both males and femmes that
are potentially capable of reproduction, but that in
general ail the eggs of the colony are actually produced
by the large-bodied female, whose consort is the maie
that has lost his wings. In other words, this fertile
[133]
INSECTS
female corresponds with the "queen" in a hive of bees;
but, unlike the queen bee, the queen termite allows the
"king" termite to live with her throughout ber lire in the
community.
It appears, then, that the termite community is a com-
plex society of castes, for we must now add to the worker
and soldier castes the two castes of potentially repro-
ductive individuals, and the "royal" or actual producing
caste, consisting of the king and the queen. We are thus
introduced to a social state quite different from anything
known in our own civilization, for, though we may have
castes, the distinctions between them are largely matters
of polite concession by the less aspiring members of the
communitv. We theoretically claire that we are ail born
equal. TÎaough we know that this is but a gratifying
illusion, our inequalities at least do hOt go by recognized
caste. A termite, however, is literally born into his
place in society and eventually has his caste insignia in-
delibly stamped in the structure of his body. This state
of affairs upsets ail our ideas and doctrines of the funda-
mental naturalness and rightness of democracy; and, if
it is true that nature not only recognizes castes but
creates them, we must look more closely into the affairs
of the termite society to see how such things may corne
about.
Let us go back to the swarm of winged males and
females that have issued from the nest. The birds are
already feeding upon them, for the termites' powers of
flight are at best feeble and uncertain. The winds have
scattered them, and in a short rime the fluttering horde
will be dispersed and probably most of its members will
be destroved one way or another. The object of the
swarming, however, is the distribution of the insects, and,
if a few survive, that is ail that will be necessary for the
continuance of the race. When the fluttering insects
alight they no longer bave need of their wings, and by
brushing against olects, or bv twisting the body until
I J341
TERMITES
the tip of the abdomen cornes against the wing bases,
the encumbering organs are broken off. It may be
observed that there is a suture across the base of each
wing just to make the breaking easy.
The now wingless termites, being young males and
females just corne to maturity, naturally pair off; but
Fro. 80. The second forrn, or short-winged reproductive caste,
of Reticuliterraes tibialis. (From Banks and Snyder)
A, rnale. B, fernale
hot for a companionate marriage, which, it must be
confessed, is the popular form of matrimony with most
insects. The termites take the vows of lifetime fidelity,
or "till death do us part," for with the female termite
intensive domesticity and maternitv are the ruling pas-
sions. To find a home site and there round a colony is
her consuming ambition, and, whether the maie likes
it or hot, he must accept her conditions. The female,
therefore, searches out a hole or a crevice in a dead tree
or a decayed stump, or crawls under a piece of wood
lying on the ground, and the maie follows. If the site
[ I35 ]
INSECTS
proves suitable, the fernale begins digging into the wood
or into the ground beneath it, using her jaws as exca-
vating tools, perhaps helped a little by the maie, and
soon a shaft is sunk at the end of which a cavity is hol-
lowed out of sufficient size to accornrnodate the pair and
to serve the purposes of a nest where true rnatrirnony
m ay begin.
Naturally it would be a very difficult rnatter to follow
the whole course of events in the building of a termite
cornrnunity frorn one of these newly married pairs, for
the termites live in absolute seclusion and any disturbance
of their nests breaks up the routine of their lives and
frustrates the efforts of the investigator. Many phases,
however, of the life and habits of our cornrnon eastern
United States termites, particularly of species belonging
to the genus Reticulitermes, have been discovered and
recorded in nurnerous papers by Dr. T. E. Snyder of the
U. S. Bureau of Entornology, and, thanks to Doctor
Snyder's work, we are able to give the following accourir
of the life of these termites and the history of the de-
veloprnent of a fairly cornplex cornrnunity fforn the
progeny of a single pair of insects.
The young rnarried couple live amicably together in
conjugal relations within their narrow cell. The maie,
perhaps, was forced to eject a would-be rival or two, but
eventually the rnouth of the tunnel is perrnanently sealed,
and fforn now on the lives of this pair will be cornpletely
shut in frorn the outside world. In due tirne, a rnonth
or six weeks after the rnating, the fernale lays ber first
eggs, six or a dozen of thern, deposited in a rnass on the
floor of the charnber. About ten days thereafter the
eggs hatch, and the new home becornes enlivened with a
brood of little termites.
The young termites, though active and able to run
about, are hOt capable of feeding thernselves, and the
parents are now conffonted.with the task of keeping a
dozen growing appetites appeased. The feeding formula
[ 3 6 ]
TERMITES
of the termite nursery calls for predigested wood pulp;
but fortunately this does not have to be supplied from
outside--the walls of the house furnish an abundance of
raw material and the digesting is done in the stomachs
of the parents. The pulp needs then only to be regurgi-
tated and handed to the infants. This feature in the
termite economy bas a double convenience, for not only
are the young inexpensively fed, but the gathering of
the food automatically enlarges the home to accommodate
the increasing need for space of the growing family.
That insects should gnaw tunnels through dead wood
is not surprising; but that they should be able to subsist
on sawdust is a truly remarkable thing and a dietetic
feat that few other animais could perform. Dry wood
consists mostly of a substance called cellulose, which,
while it is related to the starches and sugars, is a carbo-
hydrate that is entirely indigestible to ordinary animais,
though eaten in abundance as a part of all vegetable
food. The termites, however, are unusually gifted, not
with a special digestive enzyme, but with minute, one-
celled, cellulose-digesting protozoan parasites that lire
in their alimentary canals. It is through the agency of
their intestinal inhabitants, then, that the termites are
able to lire on a diet of dead wood. The young termites
receive some of the organisms with the food given them
by their parents and are soon able to be wood eaters
themselves. Not ail termites, however, are known to
possess these intestinal protozoa, and, as we shall see,
many of them feed on other things than wood.
The termite brood thrives upon its wood-pulp diet,
and by December following the spring in which the young
were hatched, the members of the new generation begin
to attain maturity after having progressed through a
series of moltings, as does any other growing insect. But
observe, the individuals of this generation, instead of
developing into replicas of their parents, have taken on
the form of workers and soldiers! However, one should
[137]
INSECTS
never express surprise when dealing with insects; and for
the present we must accept the strange deve[opment
of the young termites as a matter of fact, and pass on.
During the middle of winter things remain thus in the
new familv colonv. The members of termite species
that lire in the ground, or that pass from wood into the
ground, probably have tunneled deep into the earth for
Flc. 8. A queen oi r the
third form, or wingless re-
productive caste, of Reti-
culitermes flaipes. (From
Banks and Snyder)
protection flore the cold. But in
February, the mother termite, now
the queen of the brood, responds
again to the urge of maternity with
some more eggs, probably with a
greater nt, mber this rime than on
the first occasion. A month later,
or during March, the termitary is
once more enlivened with young
termites. The king and the queen
are now, however, relieved of the
routine of nursery duties bv the
workers of the first brood. The
latter take over the feeding and
care of their new brothers and
sisters, and also do ail the excava-
tion work involved in the enlarging
of the home.
In the spring the termites as-
cend to the st, rface of the ground
beneath a board or log, or at the
base of a stump, and reoccupy
their former habitation. As the
galleries are extended, the family
moves along, slowly migrating thus
to uneaten parts of the wood and leaving the old tunnels
behind them mostly packed with excreted wood-pt, lp and
earth.
When June cornes again, the young family may consist
of several dozen individuals; but ail, except the king and
[ 38 ]
TERMITES
queen, are soldiers and workers, the latter much out-
numbering the former. During the second year, the queen
lays a still greater number of eggs and probably produces
them at more frequent intervals. With the increase in
the activity of her ovaries, her abdomen enlarges and she
takes on a matronly appearance, attaining a length fully
twice that of her virgin figure and a girth in proportion.
The king, however, remains faithful to his spouse; and
he, too, may fatten up a little, sufficiently to give him
some distinction amongst his multiplying subjects. The
termite king is truly a king, in the modern way, for he has
renounced ail authority and responsibility and leads a
care-free lire, observing only the decorums of polite
society and adhering to the traditions of a gentleman;
but he also achieves the highest distinction of democracy,
for he is literallv the father of his country.
Another year rolls by, bringing more eggs, more workers,
more soldiers. And now, perhaps, other forms appear
in the maturing broods. These are marked at a certain
stage of their development by the possession of short
wing stubs or pads on the back of the normally wing-
bearing segments. With succeeding molts the wing pads
become larger afid larger, until they finally develop, in
most of these individuals, into long wings like those of
the king and the queen when they first flew out from the
parent colony. At last, then, the new family is to have
its first swarm; and when the fully-winged members are
ail ready for the event and the proper kind ofday arrives,
the workers open a few exits from the galleries, and the
winged ones are off. We already know their history,
for they will only do what their parents did before them
and what their ancestors have done for millions of gener-
ations, l.et us go back to the galleries.
A few of the individuals that developed winged pads
are fated to disappointment, for their wings never grow to
a functional size and they are thereby prevented from
joining the swarm. Their reproductive organs and their
[ 39 ]
INSECTS
instincts, however, attain rnaturity, and these short-
winged individuals, therefore, becorne rnales and fernales
capable ofprocreation. They differ frorn the fully-winged
sexual forrns in a few respects other than the length of the
wings, and they constitute a true caste of the termite
comrnunity, that of the short-winged males and 2(emales
(Fig. 80). The rnernbers of this caste rnature along
with the others, and, Doctor Snyder relis us, rnany of
thern, regardless of their handicap, actually leave the nest
at the tirne the long-winged caste is swarrning; as if in
them, too, the instinct for flight is felt, though the organs
for accornplishing it are unable to play their part. Just
what becornes of these unfortunates is a rnystery, for
Doctor Snyder says that after the swarrning none of thern
is to be found in the nest. It rnay be that some of thern
pair and round new colonies after the rnanner of the
winged forrns, but the facts concerning their history are
hot known. It is at least true that colonies are sorne-
rimes found which bave no true royal pair, but in which
the propagating individuals are rnembers of this short-
winged reproductive caste.
Finally, there are also found in the termite colonies
certain Viingless individuals that otherwise resemble the
winged forrns, and which, as the latter, are functionally
capable of reproduction when rnature. These individuals
constitute a third reproductive caste--the wing]ess males
and.females. Little is known of the rnernbers of this
caste, but it is surrnised that they rnay leave the nests
by subterranean passages and found new colonies of their
ovin.
Just how long the prirnary queen of a colony can keep
on laying eggs is hot known, but in the course of years
she norrnally cornes to the end of her resources, and before
that tirne she rnay be injured or killed through sorne ac-
cident. Her death in any case, however, does hot rnean
the end of the colony, for the king rnay provide for the
continuance of his race, and at the saine tirne console
TERMITES
himself in his bereavement, by the adoption of a whole
harem of young short-winged females. But if he too
should be lost, then the workers give the succession to
one or more pairs of the second- or third-caste repro-
ductive forms, to whom they grant the royal prerogatives.
The progeny of any of the fertile castes will include the
caste of the parents and all castes below them. In other
words, only winged forms can produce the whole series of
castes; short-winged parents can hot produce long-winged
offspring; and wingless parents can hot produce winged
Fç. 82. The usual king (A) and queen (B), or winged repro-
ductive caste after having Iost the wings (fig. 79), of Reticuli-
termesflavipes. (From Banks and Snyder)
offspring of any form; but both short-winged and wing-
less parents can produce soldiers and workers. It ap-
pears, therefore, that each imperfect fertile insect lacks
something in its constitution that is necessary for the pro-
duction of a complete termite individual.
The production of constitutionally different castes
from the eggs of a single pair of parents would be a
[ 4  ]
INSECTS
highly disconcerting event if it happened anywhere else
than in a termite colony, where it is the regular thing.
Bt, t the fact of its being regular with termites makes it
none the less disconcerting to entomologists, for it seems
to defv the ver}" laws of heredity.
The're can be no doubt of the utility of a caste system
where the menbers of each caste know their places and
their duties, and where nobody ever thinks of starting
a social revoit, tion. But we shot, ld like to know how
such a svstem was ever established, and how individuals
of a fanqilv are hot only born different but are ruade to
adroit it and to act accordingly.
These are abstruse qt,estions, and entomologists are
divided in opinion as to the proper answers. Some have
maintained that the termite castes are hot distinguished
when the various individuals are young, but are pro-
dt,ced later by differences in the feeding--in other words,
it is claimed the castes are ruade to order by the termites
themselves. One particular objection to this view is that
no one has succeeded in finding out what the miraculous
pabulun mav be, and no one has been able to bring about
a structural change in any termite by controlling its diet.
On the other hand, it has been shown that in some species
there are actual differences in the young at the rime of
hatching, and such observations establish the fact that
insects from eggs laid by one female tan, at least, give
fise to offspring of two or more forms, beside those of
sex, and that potential differences are determined in the
eggs. It is most probable that in these forms no struc-
tural differences could be discovered at an early embryonic
period, and hence it may be that, where differences are
hot perceptible at the time of hatching, the period of
differentiation has only been delayed to a later stage of
growth. It is possible that a solution to the problem of
the termite castes will be found when a study of the eggs
themselves bas been ruade.
We may conclude, therefore, that the structural differ-
[ 4 OE ]
TERMITES
ences between the termite castes are probably innate,
and that they arise from differences in the constitutional
elements of the germ cells that direct the subsequent
development of the embryos in the eggs and of the young
after hatching.
Still, however, there remain questions as to the nature
of the force that controls termite behavior. Whv do the
termites remain together in a community instead of
scattering, each to live its own lire as do most other in-
sects? Whv. do the workers accept their lot and perform
ail the menial duties assigned to them ? Why do the sol-
diers expose themselves fo danger as defenders of the
nesrs? Structure can account for rhe things it is im-
possible for an animal to do, but if can hot explain positive
behavior where seemingly rhe animal makes a choice
between manv lines of possible action open to it.
In the communirv of rhe cells that make up rhe body
of an animal, as we learned in Chapter IV, organization
and controi are brought about eirher rhrough the nerves,
which rransmir an activating or inhibiring force to each
cell from a central controlling station, or through chemical
substances thrown inro the blood. In rhe insect com-
munity, however, there is norhing corresponding to
either of these regulating influences; nor is there a law-
making individual or group of individuals as in human
socieries, nor a police force fo execure the orders if any
were issued. If would seem rhat there must be some
inscrutable power rhar mainrains law and order in the
ternaire galleries. Are we, then, fo adroit rhat there is a
"spirir of the nest," an "âme collective," as Maeterlinck
would have us believe--some pervading force that unites
rhe individuais and guides the destinies of the colony
as a whole? No, scientists can hot accept any such idea
as that, because it assumes that nature's resources are
no greater than those of man's imagination. Nature is
alwavs narural, and ber ways and means of accomplish-
ing nyrhing, when once discovered, never invoke things
[ 143]
INSECTS
that the human mind can hOt grasp, except in their
ultimate analysis into first principles. Those who have
faith in the consistency of nature endeavor to push a
little farther into the great unknown knowable.
There are a few things known about the termites that
help to explain some of the apparent mysteries concerning
them. For example, the members of a colony are for-
ever licking or nibbling at one another; the workers ap-
pear to be always cleaning the queen, and they are as-
siduous in stroking the young. These labial attentions,
or lip affections, moreover, are hot unrewarded, for it
appears that each member of the colony exudes some
substance through its skin that is highly agreeable to
the other members. Furthermore, the termites ail feed
one another with food material ejected from the alimen-
tary canal, sometimes from one end, sometimes from the
other. Each individual, therefore, is a triple source of
nourishment to his fellows--he has to offer exudates
from the skin, crop food from the mouth, and intestinal
food from the anus--and this mutual exchange of food
appears to form the basis for much of the attachment
that exists among the members of the colony. It accounts
for the maternal affections, the care of the queen and the
young by the workers, the brotherly love between the
workers and the soldiers. The golden rule of the termite
colony is "feed others as you would be fed by them."
The termites, therefore, are social creatures because,
for physical reasons, no individual could lire and be
happy away from his fellows. The saine might be said
of us, though, of course, we like to believe that our social
instincts have hot a purely physical basis. Be that as
it may, we must recognize that any kind of social tie
is but one of various possible means by which the benefits
of community lire are insured to the members of the
community.
The custom of food exchange in the termite colonies
can hot be held to account by any means for ail the things
[ I44]
TERMI'FES
that termites do. Where other explanations rail, we have
always to rail back on "instinct." A true instinct is a
response bred in the nervous system; and the behavior
of termites, as of ail other insects, is largely brought
Fç. 8 3. A fore wing of a termite, Kaloterrnes approximatus,
showing the humerai suture (hs) where the wing breaks off when
it is discarded
about by automatic reflexes that corne into action when
external and internal conditions are right for their pro-
duction. The physical qualities of the nervous system
that make certain reactions automatic and inevitable
are inherited; they are transmitted from parent to off-
spring, and bring about ail those features of the animal's
behavior that are repeated from generation to genera-
tion and which are hot to be attributed to the individual's
response to environmental changes.
The termites have an ancient lineage, for though no
traces of their family have been round in the earlier
records, there can be no doubt that the ancestors of the
termites were closely related to those of the roaches; and
the roach family, as we have seen in Chapter III, may be
reckoned among the very oldest of winged insects. In
human society it means a great deal to belong to an "old
family," at least to the members of that family; but in
biology generally it is the newer forms, the upstarts of
more recent times, that attain the highest degree of
organizatlon; and most of the social insects--the ants,
the bees, and the wasps--belong to families of compara-
tively recent origin. It is refreshing, therefore, to find
[I451
INSECTS
the belief in aristocracy vindicated by the ancient and
honorable line of descent represented by the roaches and
flowering in the termites.
One particular piece of evidence of the roach ancestry
of the termites is furnished by the wings. With most
termites the wings (Fig. 83) are hot well developed, and
Ftc,. 84. Wings of AIastotermes, the hind wing with a basal
expansion similar to that of the hind wing of a roach (fig.
suggesting a relationship between termites and roaches
their muscles are partly degenerate. In some forms, how-
ever, the wings (Fig. 84) are distinctly of the roach type
of structure (Fig. 53), and these forms are undoubtedly
more closely representative of the ancestral termites than
are the species with the usual termite wing structure.
Our termites and those of other temperate regions con-
stitute the mere fringes of termite civilization. The ter-
mites are particularly insects of warm climates, and it is
in the tropics that they find their most congenial environ-
ment and attain the full expression of their possibilities.
In the tropics the characteristic termites are hot those
that inhabit dead wood, but species that construct detinite
and permanent nests, some placed beneath the ground,
[ I461
TERMITES
others reared above the surface, and still others built
against the trunks or branches of trees. Different species
employ different building materials in the construction
of their nests. Some use particles of earth, sand grains,
or clay; others use earth mixed with saliva; still others
make use of the partly digested wood pulp ejected from
their bodies; and some use mixed materials. Certain
kinds of tropical termites, moreover, have foraging habits.
Fro. 8 5. Vertical section of an underground nest of an African termite, Terme«
badius. (From Hegh, after Fuller)
The large central chamber is the principal "fungus garden"; in the wall at the
left is the royal chamber (rc); tunnels lead from the main part ofthe nest to
smaller chambers containing fungus, and to the small mounds at the surface
Great armies of workers of these species leave the nests,
even in broad daylight, and march in wide columns
guarded by the soldiers to the foraging grounds, where
they gather bits of leaves, dead stems, or lichens, and
return laden with provender for home consumption.
The underground nests (Fig. 8 5) consist chiefly of a
['47]
INSECTS
cavity in the earth, perhaps two by three feet in diameter
and a foot beneath the surface, walled with a thick cernent
lining; but frorn this charnber there rnay extend tunnels
upward to the surface, or horizontally to other smaller
charnbers located at a distance frorn the central one.
The termites that lire in these nests subsist principally
upon horne-grown food, and it is in the great vaulted
central charnber that they raise the staple article of their
diet. The cavity is filled almost entirely with a porous,
spongy rnass of living fungus. The fungi as we ordinarily
see them are the toadstools and rnushrooms, but these
fungus forms are merely the fruiting bodies sent up frorn
a part of the plant concealed beneath the ground or in
the dead wood; and this hidden part has the form of a
network of fine, branching threads, called a OEycelium.
The rnyceliurn lires on decaying wood, and it is the
rnycelial part of the fungus that the termites cultivate.
They feed on srnall spore-bearing stalks that sprout frorn
the threads of the rnyceliurn. The substraturn of the
termite fungus beds is generally rnade of pellets of partly
digested wood pulp.
The nests that termites erect above the ground include
the rnost rernarkable architectural structures produced
by insects. They are round in South America, Australia,
and particularly in Africa. In size they vary frorn rnere
turrets a few inches high to great edifices six, twelve,
or even twenty feet in altitude. Sorne are simple rnounds
(Fig. 86 A), or rnere hillocks; others have the form of
towers, obelisks, and pyrarnids (B); still others look
like fantastic cathedrals with buttressed walls and taper-
ing spires (Fig. 87) ; while lastly, the strangest of ail re-
semble huge toadstools with thick cylindrical stalks and
broad-brirnrned caps (Fig. 86 C). Many of the termites
that build mound nests are also fungus-growing species,
and one charnber or several chambers in the nest are
given over to the fungus culture.
Termite nests built in trees are usually outlying retreats
[ 148 ]
TERMITES
of colonies that live in the ground, for such nests (Fig.
86 D) are connected with an underground nest by covered
runways extending down the trunk of the tree.
The queens of nearly all the termites that lire in perma-
nent nests attain an enormous size by the growth of the
abdomen, the body becoming thus so huge that the royal
,! -.,.-- ...-, --'- I -\
'ï"'" " ::'-- t " ç
«. -: "'";"  " / " ;"\  " ..«-
., .-  «-.), I _.- «.,,, \
 ,,,,/' ..... ..,., .: «),' t: 
l:,, ." , .,..,,«.  ",/ ;!'-"L ,,,
FzG. 86. Four common types of above-ground nests ruade by tropical termites
A, type of small mound nest, varying from a few inches to several feet in helght.
B, type of a large tower or steeple nest, reaching a height of 9 or zo feet. C,
a mushroom-shaped nest, ruade by certain African termites, from 3 to z6 inches
high. D, a tree nest, showing the covered runway going down to the ground
female ls rendered completely helpless, and must be
attended in ail her wants by the workers. With such
species the queen is housed in a special royal chamber
which she never leaves. Her body becomes practically a
great bag in which the eggs are produced, and so great
s the fertilitv, of one of these queens that the ripened eggs
continually issue from ber body. It has been estimated
that in one such species the queen lays four thousand
eggs a day, and that in another species her daily output
may be thirty thousand. Ten million eggs a year is pos-
[ I49]
INSECTS
Type of pinnacled nest ruade by spe¢ies of African termites, some-
rimes reaching a height of twenty feet or more
[ I5o]
TERMITES
sibly a world record in ovulation. The royal chamber is
usually placed near the fungus gardens, and as fast as
the eggs are delivered bv the queen the attendant workers
carry them off to the garden and distribute them over
the fungus beds, where the young on hatching can feed
and grow without further attention.
From a study of the termites we mav draw a few lessons
for ourselves. In the first place, we see that the social
form of lire is only one of the ways of living; but that,
wherever itis adopted, it involves an interdependence of
individuals upon one another. The social or community
way of living is best pronloted bv a division of labor anlong
groups of individuals, allowing each to specialize and there-
by to attain proficiency in his particular kind of work.
The means by which the ternaites bave achieved the bene-
fits of social lire are hot the saine as those adopted by
the ants or social bees, and they bave little in common
with the principles of our own social organization. All of
which goes to show that in the social world, as in the
physical world, the end alone justifies the means, so far as
nature s concerned. Justice to the individual is a human
concept; we strive to equalize the benefits and hardships
of the social form of lire, and in so far as we achieve this
aire out civilization differs from that of the insects.
[ 51 ]
CHAPTER VI
PLANT LICE
"PL.T lice! Ugh," you say, "who wants to read about
those nasty things! Ail I want to know is how to get rid
of them." Yes, but the very fact that those sort green
bugs that cover your roses, your nasturtiums, your cab-
bages, and your fruit trees at certain seasons reappear
so persistently, after you think you bave exterminated
them, shows that they possess some hidden source of
power; and the secrets of a resourceful enemy are at least
worth knowing--besides, they may be interesting.
Really, however, insects are hOt our enemies; they are
only living their appointed lives, and it just happens that
we want to eat some of the saine plants that they and their
ancestors bave always fed on. Our trouble with the in-
sects is just that saine old economic conflict that has bred
the majority of wars; and, in the case between us and the
insects, it is we who are the aggressors and the enemies of
the insects. We are the newcomers on the earth, but we
fume around because we find it already occupied by a host
of other creatures, and we ask what right bave they to be
here to interfere with us! Insects existed millions of
years before we attained the human form and aspirations,
and they have a perfectly legitimate right to everything
they feed on. Of course, it must be admitted, they do hot
respect the rights of private property; and therein lies
their hard luck, and ours.
The plant lice are well known to anyone who has a
garden, a greenhouse, an orchard, or a field of grain.
Some call them "green bugs"; entomologists usually call
[t52]
PLANT LICE
them aphids. A single plant louse is an aphis, or an aphid;
more than one are usually called aphides, or aphids.
The distinguishing feature of the plant lice, or aphids,
as we shall by preference call them, is their manner of feed-
ing. All the insects described in the preceding chapters
eat in the usual fashion of biting off pieces of their food,
chewing them, and swallowing the masticated bits. The
Fit. 88. Group of green apple aphids feeding along a rib on
under surface of an apple leaf
aphids are sucking insects; they feed on the juices of the
plants they inhabit. Instead ofjaws, thev bave a piercing
and sucking beak (Fig. '9), consisting of an outer sheath
inclosing four slender, sharp-pointed bristles which can be
thrust deep into the tissues of a leaf or stem (Fig. 89 B).
Between the bristles of the innermost pair (Fig. 9 o, Mx)
are two canals. Through one canal, the lower one (b), a
liquid secretion from glands o( the head is injected into the
plant, perhaps breaking down its tissues; through the
other (a) the plant sap and probably some of the proto-
plasmic contents of the plant cells are drawn up into the
mouth. A sucking apparatus like that of the aphids is
possessed by ail insects related to the aphids, comprising
the order Hemiptera, and will be more fully described
[ 53]
INSECTS
in the next chapter, which treats of the cicada, a large
cousin of the aphids.
When we observe, now, that different insects feed in
two quite different ways, some by means of the biting
type of mouth parts, and others by means of the sucking
type, it becomes evident that we must know which kind
of insect we are dealing with in the case of pests we may be
trying to control. A biting and chewing insect can be
killed by the mere expedient of putting poison on the out-
side of its food, if it does not become aware of the poison
and desist from eating it; but this method would hot
work with the piercing and sucking insects, which extract
their food from beneath the surface of the plants on
which they feed. Sucking insects are, therefore, to be
destroyed by means
of sprays or dusts
that will kill them by
contact with their
bodies. Aphids are
usually attacked with
irritant sprays, and in
general it is hot a
difficult matter to rid
infested plants of
them, though in most
cases the spraying
must be repeated
through the season.
When any species
of aphis becomes well
established on a plant,
F. 8 9 . The way an aphis feeds on the
juices of a plant
A, an aphis with its beak thrust into a rib of a
leaf. B, section through the midrib of a young
apple leaf, showing the mouth bristles from the
beak of an aphis penetrating between the cells
of the leaf tissue to the vascular bundles,
while the sheath of the beak is retracted by
folding back beneath the head
the infested leaves
(Fig. 88) may be al-
most as crowded as an
East Side street on a
hot summer after-
noon. But there is
[54]
PLATE 2
E
D
The green apple aphis (.dphis pomi)
A, adult sexual female; B, adult maie; C, young femme; D, female lav-
ing an egg; E, eggs, which turn from green to black after thev are laid.
(Enlaed about -o times)
PLANT LICE
no bustle, no commotion, for each insect has its sucking
bristles buried in the leaf, and its pump is busy keeping
the stomach supplied with liquid food. The aphis crowds
are mere herds, hot communities or social groups as in
the case of the termites, ants, or bees.
Wherever there are aphids there are ants, and in con-
trast to the aphids, the ants are always rushing about ail
over the place as if they were looking for something and
each wanted to be the first to find it. Suddenly one spies
a droplet of some clear liquid lying on the leaf and gob-
bles it up, swallowing it so quickly that the spherule
seems to vanish by magic, and then the ant is off again
in the saine excited manner. The explanation of the
presence and the actions of the ants among the aphids
is this: the sap of the plants furnishes an unbalanced diet,
the sugar content being far too great in proportion to the
protein. Consequently the aphids eject from their bodies
drops of sweet liquid, and it is this liquid, called "honey
dew," that the ants search out so eagerly. Some of the
ants induce the aphids to give up the honey dew by strok-
ing the bodies of the latter. The glistening coat often
seen on the leaves of city shade trees and the shiny liquid
that bespatters the sidewalks beneath is honey dew dis-
charged from innumerable aphids infesting the under sur-
faces of the leaves.
In studying the termites, we learned that it is possible
for a single pair of insects to produce regularly several
kinds of offspring differing in other ways than those of
sex. In the aphids, a somewhat similar thing occurs in
that each species may be represented by a number of
forms; but with the aphids these different forms con-
stitute successive generations. If events took place in
a human family as they do in an aphid family, children
born of normal parents would grow up to be quite different
from either their father or their mother; the children of
these children would again be different from their parents
and also from their grandparents, and when mature they
[551
INSECTS
perhaps would migrate to some other part of the country;
here thev would have children of their own, and the new
fourth géneration would be unlike any of the three pre-
ceding; this generation would then produce another,
again different; and the latter would return to the home
town of their grandparents
Cm Nx and great-grandparents, and
\ / here bring forth children that
\ .a would grow up in the like-
/
ness of their great-great-
great-grandparents! This
seems like a fantastic tale of
fiction, too preposterous to-
be taken seriously, but it is a
commonplace fact among the
 aphids, and the actual gen-
/ ealogy mav be even more
Lb complicated than that above
outlined. Moreover, the
Fro. 9 o. Cross-section through storv is hOt yet complete,
the base of the beak of an aphis, for i't musr be added that ail
(From Davidson)
Theouter sheath of the b«ak is the the generations of the aphids,
labium (Lb), covered basally by except one in each series, are
the labrum (Lin). The four in-
closed bristles are the mandibles composed entirely of females
(Md) and the maxillae (Mx), the capable in themselves of re-
latter containing between rhem a
food canal (a) and a salivary canal production. In warm " cil-
(b). Only th« inner walls of th« mates, it appears, the female
labrum and labium are shown in
thesection succession may be uninter-
rupted.
How insects do upset out generalizations and our peace
of mind ! We bave heard of feminist reformers who would
abolish men. With patient scorn we bave listened to their
predictions of a millenium where males will be unknown
and unneeded--and here the insects show us hot only that
the thing is possible but that it is practicable, at least for
a certain length of time, and that the time can be in-
definitely extended under favorable conditions.
[561
PLANT LICE
Since special cases are alwavs more convincing than
general statements, let us follov the seasonal historv of
some particular aphids, taking as examples the species
that commonly infest the apple.
Let the rime be a day in the early part of Match.
Probably a raw, gusty wind is blowing from the north-
west, and only the silver maples with their dark purplish
clusters of frowzy flowers already open give anv sug-
gestion of the approach of spring. Find an old" apple
tree somewhere that has hOt been sprayed, the kind of
tree an entomologist always likes to have around, since
it is sure to be fidl of insects. Look closely at the ends
of some of the twigs and
you will probably find a
number of little shiny
black things stuck close
to the bark, especially
about the bases of the
buds, or tucked under the
projecting edges of scars
and tiny crevlces (Fig.
9). Each little speck is
oral and about one thirty-
sixth of an inch in length.
To the touch the ob-
jects are firm, but elastic,
and if you puncture one a
pulpy liquid issues from
lt; or soit appears, at
least, to the naked eve--
a microscope would show
that in this liquid there is
Fro. 9 . Aphis eggs on apple twigs in
March; an enlarged egg below
organization. In short, the tinv capsule contains a young
aphid, because it is an aphid egg. The egg was de-
posited on the twig last fall by a femme aphis, and its
living contents have remained alive since then, though
fully exposed to the inclemencies of winter.
[ 157]
INSECTS
Immediately after being laid in the fall, the germ
nucleus of the aphis egg begins development, and soon
forms a band of tissue lying lengthwise on the under sur-
face of the yolk. Then this scarcely-formed embryo
undergoes a curious process of revolution in the egg,
turning on a crosswise axis head foremost into the yolk
and finally stretching out within the latter with the back
down and the head toward the original rear end of the
egg. Thus it rernains through the winter. In March
it again becomes active, reverses itself toits first posi-
tion, and now compIetes its development.
The date of hatching of the apple aphis eggs depends
much upon the weather and will vary, therefore, ac-
cording to the season, the elevation, and the latitude; but
in latitudes from that of Washington north, itis some
time in April, usually from the first to the third week of
the month. The eggs of most insects resemble seeds in
Fz. 9-- Eggs of the green
apple aphis with outer cover-
ings split before hatching;
below, an egg removed from
its covering
their capacity for lying inert un-
til proper conditions of warmth
and moisture bring forth the
creature biding its time within.
The eggs of one of the apple
aphids, however, are killed by
premature warm weather, or if
artificially warmed too long be-
fore the normal time of hatching.
In general, the final development
of the aphis embryos keeps pace
with the development of the
apple buds, since both are con-
trolled by the saine weather con-
ditions, and this coordination
usually insures the young aphids
against starvation; but the eggs
commonly hatch a little in ad-
rance of the opening of the buds,
and a subsequent spell of cold
15 8 ]
PLANT LICE
weather may give the young lice a long wa]t for their
first meal.
The approaching rime of hatching is s]gnaled in most
Fro. 93- Hatching of the green apple aphis, ,'lphis pomi
A, the agg. B, an egg with the outer coat split. C, the sarneegg with the
inner shell split atone end. D-F, three successive stages in the emergence of
the young insect. G-J, shedding the hatching membrane. K, the ernpty
eggshell. L, the young aphid
[ I59]
INSECTS
cases by the splitting of an outer sheath of the egg (Fig.
92), exposing the glistening, black, true shell of the egg
within. Then, from one to several days later, the shell
itself shows a cleft within the rupture of the outer coat,
extending along hall the length of the exposed egg sur-
face and down around the forward end (Fig. 93 C).
From this split emerges the sort head of the young aphis
(D), bearing a hard, toothed crest, evidently the instru-
ment by which the leathery shell was broken open, and
for this reason known as the "egg burster." Once ex-
posed, the head continues to swell out farther and far-
ther as if the creature had been compressed within the
egg. Soon the shoulders appear, and now the young
aphis begins squirming, bending, inflating its fore parts
and contracting its rear parts, until it works its body
mostly out of the egg (E, F) and stands finally upright
on the tip of its abdomen which is still held in the cleft
of the shell (G).
The young aphis at this stage, however, like the young
roach, is still inclosed in a thin, tight-fitting, membranous
bag having no pouches for the legs or other members,
which are ail cramped within it. The closely swathed head
swells and contracts, especially the facial part, and sud-
denly the top of the bag splits close to the right side of
the egg burster (Fig. 93 H). The cleft pulls down over
the head, enlarges to a circle, slides along over the shoul-
ders, and then slips down the body. As the tightly stretched
membrane rapidly contracts, the appendages are freed
and swing out from the body (I). The shrunken pellicle
is reduced at last to a small goblet supporting the aphid
upright on its stalk, still held bv the tip of the abdomen
and the hind feet (I). To lilerate itself entirely the
insect must make a few more exertions (J), when, finally,
it pulls its legs and body from the grip of the drying
skin, and is at last a free young aphid (L).
The emergence from the egg and from the hatching
membrane is a critical period in the lire of an aphid. The
[ ,6o]
PLATE 3
_A
The rosy apple aphis (.qnuraphis roseus)
A, apple leaves and young fruit distorted by the aphids; B, under surface
of an infested leaf; C, immature wingless aphid (greatly enlarged); 1),
immature winged aphis
PLANT I.ICE
process may be completed in a few minutes, or it may
take as long as hall an hour, but if the feeble creature
should be unable to free itself at last from the drying and
contracting tissue, it remains a captive .strugg!ing in the
grip of its embryonic vestment until it expires. The
young aphid successfully delivered takes a few uncertain,
staggering steps on its weak and colorless legs, and then
complacently rests awhile; but after about twenty rein-
Fc. 94- Young aphids on apple buds in spring
utes or half an hour itis able to walk in proper insect
fashion, and it proceeds upward on its twig, a course
sure eventually to lead it to a bud.
While the aphid eggs are hatching, or shortly there-
after, the apple buds are opening and unfolding their
delicate, pale-green leaves, and from everywhere now
the young aphids corne swarming upon them, till the tips
are often blackened by their numbers (Fig. 94)- The
hungry horde plunges into the hearts of the buds, and
soon the new leaves are punctured with tiny beaks that
rob them of their food; and the young foliage, upon which
[ I6I ]
INSECTS
the tree depends for a
stunted and yellowed.
to spray if he has hot
The entomologist,
young aphids on the
there are three kinds
differing slightly, but
to a separate species.
proper start of its spring growth, is
Now is the time for the orchardist
already done so.
however, takes note that ail the
apple trees are hot alike; perhaps
of them in the orchard (Fig.
enough to show that each belongs
When the first buds infested are
A t3
F1ç. 95- Three species of young aphids round on apples in the spring
A, the apple-grain aphis, Rhopalosiphum prunifoliae. B, the green apple aphis,
lphis pomi. C, the rosy apple aphis, lnuraphis roseus
exhausted, the insects migrate to others, and later they
spread to the larger leaves, the blossoms, and the young
fruit. The aphids ail grow rapidly, and in the course
of two or three weeks they reach maturity.
The full-grown insects of this first generation, those
produced from the winter eggs, are entirely wingless, and
they are ail females. But this state of affairs in no wise
hinders the multiplication of the species, for these re-
markable females are able of themselves to produce off-
spring (a faculty known as parthenogenesis), and further-
more, they do hot lay eggs, but give birth to active young.
Since they are destined to give rise to a long line of sure-
mer generations, they are known as the stem mothers.
One of the three aphid species of the apple buds is
known as the green apple aphis (Fig. 95 B). During the
[ 6OE]
PLANT LICE
early part of the season the individuals of this species
are round particularly on the under surfaces of the apple
leaves. They cause the infested leaves to curl and to
become distorted in a haracteristic manner (Fig. 96).
The stem mothers (Fig. 97 .A., B) begin giving birth to
young (C) about twenty-four hours after reaching ma-
turity, and any one of the mothers, during the course of
her lire of from ten to thirty days, may produce an aver-
age family of fifty or more daughters, for ail her offspring
are females, too. When
these daughters grow up,
however, none of them is
exactly like their mother.
They ail have one more
segment in each antenna;
most of them are wing-
less (D), but many of
them have wings--some,
mere padlike stumps, but
others well developed or-
gans capable of flight
(Fig. 97 E).
Both the wingless and
the winged individuals of
this second generation are
also parthenogenetic, and
they give birth to a third
generation like them-
selves, including wing-
less, half-winged, and
fully-winged forms, but
with a greater propor- Fie. 9 6. Leaves of apple infested and
tion of the last. From distorted by the green apple aphis on
under surfaces
now on there follows a
large number of such generations continuing through the
season. The winged forms fly from one tree to another,
or to a distant orchard, and round new colonies. In
[ I63]
INSECTS
summer, the green apple aphis is round principally on
young shoots of the apple twigs, and on water sprouts
growmg in the orchard.
During the early part of the summer, the rate of pro-
duction rapidly increases in the ap.hid colonies, and in-
dividuals of the summer generatons sometimes give
birth to young a week after they themselves were born.
In the rail, however, the period of growth again is length-
ened, and the families drop offin size; until the last females
of the season produce each a scant hall dozen young,
though they mav live to a much greater age than do the
sunamer individuals.
The young summer aphids born as active insects are
inclosed at birth in a tight-fitting, seamless, sleeveless,
and legless tunic, as are those hatched from the winter
eggs. Thus swathed, each emerges, rear end first, from
the body of the mother, but is finally held fast by the
face when it is nearlv free. In this position, the ena-
bryonic bag splits over the head and contracts over the
body of the young aphid to the tip of the abdomen,
where it remains as a cap of shriveled membrane until
it finally drops off or is pushed away by the feet. The
infant, now vigorously kicking, is still held in the ma-
ternal grasp, and eventually liberates itself only after
some rather violent struggling; btt soon after if is free
it walks away to find a feeding place anaong its com-
panions on the leaf. The mother is but little concerned
with the birth of her child, and she usually continues
to feed dtring its delivery, though she may be somewhat
annoved by its kicking. The average summer female
gives birth to two or three young aphids every day.
The succession of forms in the familles is one of the
most interesting phases of aphid lire. Investigations
have shown that the winged individuals are produced
principally bv wingless forms, and experiments have
demonstrated that the occurrence of the winged forms
is correlated with changes in the temperature, the food
[ 164]
PLANT LICE
supply, and the duration of light. At a temperature
around sixty-five degrees few winged individuals ever
appear, but they are produced at temperatures either
below or above this point. Likewise it has been found
that when the food supply gives out through the drying
FIG. 97" The green apple aphis, .4phis lomi. A, B, adult stem mothers.
C, a newly-born young of the summer forms. D, a wingless summer
form. E, a winged summer form
of the leaves or by the crowding of the aphids on them,
winged forms appear, thus making possible a migration
to ffesh feeding grounds. Then, too, certain chemical
substances, particularly salts of magnesium, added to
the water or wet sand in which are growing cuttings
of plants infested with aphids, will cause an increase of
winged forms in the insects subsequently born. This
does not happen if the plants are rooted, but it shows
that a change in the food ca11 have an effect on wing
production.
1 651
INSECTS
Finally, it has recently been shown experimentally by
Dr. A. Franklin Shull that winged and wingless condi-
tions in the potato aphis may be produced artificially by
a variation in the relative amount of alternating light
and darkness the aphids receive during each twenty-four
hours. Shortening the illumination period to twelve
hours or less results in a marked increase in the number of
winged forms born of wingless parents. Continuous
darkness, however, produces few winged offspring. Maxi-
mure results perhaps are obtained with eight hours of
light. The effect of decreased light appears from Doctor
Shull's experiments to be directly operative on the young
from thirty-four to sixteen hours before birth, and it lS
hot to be attributed to any physiological effect on the
plant on which the insects are feeding.
It is evident, therefore, that various unfavorable local
conditions may give fise to winged individuals in a colony
of wingless aphids, thus enabling representatives of the
colonv to migrate in the chance of finding a more suit-
able place for the continuance of their line. The regular
production of swing and rail migrants is brought about
possibly bv the shorter periods of daylight in the earlier
and later parts of the season.
The final chapter of the aphid story opens in the rail
and, like all last chapters done according to the rules,
it contains the sequel to the plot and brings everything
out right in the end.
AIl through the spring and summer the aphid colonies
have consisted exclusively of virgin females, winged and
wingless, that give birth to virgin females in ever-in-
creasmg numbers. A prosperous, self-supporting femi-
nist dominion appears to be established. When summer's
warmth, however, gives wav to the chills of autumn,
when the food supply begins to fail, the birth rate slack-
ens and falls off steadily, until extermination seems to
threaten. Bv the end of September conditions have
reached a desperate state. October arrives, and the
[ 66]
PLANT LICE
surviving virgins give birth in forlorn hope to a brood
that must be destined for the end. But now, it appears,
another of those miraculous events that occur so fre-
quently in the lives of insects bas happened here, for the
members of this new brood are seen at once to be quite
different creatures from their parents. When they grow
up, it develops that they constitute a sexual generation,
composed of females and males, t (Plate 2 A, B.)
Feminism is dethroned. The race is saved. The mar-
riage instinct now is dominant, and if mrital relations
in this new generation are pretty loose, the time is Octo-
ber, and there is much to be accomplished before winter
comes.
The sexual females dit}er from their virgin mothers
and grandmothers in being of darker green color and in
having a broadlv pear-shaped body, widest near the end
(Plate 2 A). T]e males (B) are much smaller than the
females, their color is vellowish brown or brownish green,
and they bave long sp"derlike legs on which they actively
run about. Neither the males nor the females of the green
apple aphis have wings. Soon the females begin to pro-
duce, hot active young, but eggs (D). The eggs are de-
posited most anvwhere along the apple twigs, in crevices
where the bark is rough, and about the bases of the buds.
The newly-laid eggs are vellowish or greenish (D), but
thev soon turn to green, then to dark green, and finally
become deep black (E). There are hot many of them,
for each female lays onlv from one to a dozen; but it
is these eggs that are to remain on the trees through the
winter to produce the stem mothers of next spring, who
will start another cycle of aphid lire repeating the his-
tory of that just closed.
The production of sexual forms in the fall in temperate
climates seems to bave some immediate connection with
the lowered temperature, for in the tropics, it is said,
the aphid succession continues indefinitelv through par-
thenogenetic females, and in most tropical" species sexual
[ I67]
INSECTS
Fc. 9 8 . The rosy apple
aphis, Inuraphis roseu«, on
apple
A, a cluster of infested and
distorted leares. B, an adut
stem morher. C, young apples
dwarfed and distorted by the
feeding of the aphids
rnales and fernales are unknown. In the warmer regions
of the West Coast of the United States, species that regu-
larly produce rnales and females every rail in the East
continue without a reversion to the sexual forms.
Of the other two species of apple aphids that infest
the buds in tbe spring, one is
. 5 ) known as the ros apple aphis
t..__..g..e.,) ,. :. a-27.OE _ -l. .... (Fig. 95 C). The naine cornes
.[..._''. from the fact that the early
vv-.)'oe/J-k.,-   summer individuals of this
species ha,ce a waxy pink tint
more or less spread o.cer the
ground color of green (Plate 3),
though many of the adult
stern rnothers (Fig. 98 B) are
'.%.] of a deep purpiish color. The
early generations of the rosy
aphis infest the lea.ces (Fig.
98 A, Plate 3 A) and the young
fruit (Fig. 98 C, Plate 3 A),
causing the former to curl up
in tightly rolled spirals, and tbe
latter to become dwarfed and
distorted in forrn.
The stem mothers of the
rosy aphis give birtb partheno-
genetically to a second gen-
eration of fernales which are
mostly wingless like their moth-
ers; but in the next generation
rnany individuals have wings.
Se.ceral more generations now
rapidly follow, all females; in
fact, as with the green aphis,
no rnales are produced till late in the season. The winged
forrns, however, appear in increasing nurnbers, and by
the first ofJuly alrnost all the indi.ciduals born ha,ce wings.
[ ,68 ]
PLANT LICE
Heretofore, the species has remained on the apple trees,
but now the winged ones are possessed with a desire for a
change, a cornplete change both of scenery and of diet.
They leave the apples, and when next discovered thev are
found to have established thernselves in sumrner colonies
on those cornmon weeds known as plantains, and mostly
on the narrow-leaved variety, the rib-grass, or English
plantain (Fig. 99)-
As soon as the rni-
grants land upon the
plantains they give birth
to offspring quite unlike
themselves or any of the
preceding generations.
These individuals are of a
yellowish-green color and
nearly all of thern are
wingless (Fig. 99)- So
well do they disguise
their species that ento-
rnologists were a long
tirne in discovering their
identity. Generations of
wingless vellow fernales
now foll»w upon the
plantain. But a weed is
no fit place for the stor-
age of winter eggs, so,
with the advent of fall,
winged forms again ap-
pear In abundance, and F,ç. 99- The rosy apple aphis on nar-
row-leaved plantain in summer; above, a
these migrate back to the wingless summer form (enlarged)
apples. The rail rni-
grants, however, are of two varieties: one is sirnply a
winged fernale like the earlier rnigrants that carne to the
plantain frorn the apple, but the other is a winged rnale
(Fig. 1oo A). Both forrns go back to the apple trees, and
[ 169]
INSECTS
there the females give birth to a generation of wingless
sexual females (B), which, when mature, mate with the
males and produce the winter eggs.
The third of the aphid species that infest the spring
buds of the apple is known as the apple-grain aphis, so
called because, being a migratory species like the rosy
A
F*. *oo. The winged male(A) and the wingless sexual female (B) of the
rosy apple aphis
aphis, it spends the summer upon the leaves of grains
and grasses. The eggs of the apple-grain aphis are usually
the first to hatch in the spring, and the young aphids of
this species (Fig. 95 A) are distinguished by their very
dark green color, which gives them a blackish appear-
ance when massed upon the buds. Later they spread
to the older leaves and to the petals of the apple blossoms,
but on the whole their damage to the apple trees is less
than that of either of the other two species. The summer
history of the apple-grain aphids is similar to that of the
rosy aphis, excepting that they make their summer home
on grains and grasses instead of on plantains. In the
fall, the winged female migrants (Plate 4) corne back to
the apple and there give birth to wingless sexual females,
which are later sought out by the winged males.
It would be impossible here even to enumerate the
[ J7o]
PLANT LICE
Flç. Ioi. Some common aphids of the garden
A, winged form of the potato aphis, Illinoia aolanifofii, one of the largest of
the garden aphids. B, winged form of the peach aphis, Myzus persicae,
which infests peach trees and various garden plants. C, wingless form of
the peach aphis. D, wingless form of the melon aphis, Iphis gossypii. E,
winged form of the melon aphis
[ 7 ]
INSECTS
many species of aphids that infest our common field and
garden plants (Fig. Ol) and cultivated shrubs and trees,
to say nothing of those that inhabit the weeds, the wild
shrubbery, and the forest trees. Almost every natural
group of plants has its particular kind of aphid, and many
of them are migratory species like the rosy and grain
aphis of the apple. There are root-inhabiting species as
well as those that live on the leaves and stems. The
Ph.vlloxera, that pest of vineyards in California and
France, s a root aphid. Those cottony masses that
often appear on the apple twigs in late summer mark
the presence of the woolly aphis, the individuals of which
exude a fleecy covering of white waxy threads from their
backs. The woolly aphis is more common on the roots
of apple trees, being especially a pest of nursery stock, but
it migrates to both the twigs and the roots of the apple
from the elm, which is the home of its winter eggs.
An underground aphid of particular interest is one that
lives on the roots of corn. We bave seen that ail aphids
are much sought after by ants because ol c the honey dew
they excrete, a substance greatly relished and prized by
the ants. It is said that some ants protect groups of
aphids on twigs by building earthen sheds over them; but
the corn-root aphis owes its very existence to the ants.
A species of ant that makes its nests in cornfields runs
tunnels from the underground chambers of the nests to
the bases ofnearby cornstalks. In the fMI the ants gather
the winter eggs of the aphids from the corn roots and take
them into their nests where they are protected from
freezing during the winter. Then in the spring the ants
bring the eggs up from the storage cellars and place
them on the roots of various early weeds. Here the
stem mothers hatch and give rise to several spring gen-
erations; but, as the new corn begins to sprout, the ants
transfer manv of the aphids to the corn roots, where
thev lire and multiply during the sumnler and, in the fall,
give birth to the sexual males and females, which produce
172 ]
PLANT LICE
the winter eggs. The eggs are again collected by the ants
and carried to safety for the winter into the depths of their
underground abodes. All this the ants do for the aphids
in exchange for the honey dew they receive from them.
The ants bave so domesticated these corn-root aphids
that the aphids would perish without their care. The
fariner, therefore, who would rid his cornfield of the aphid
pest, proceeds with extermination measures against the
ants.
The crowded aphid colonies exposed on stems and
leaves naturallv form the happy hunting grounds for a
Fro. io. A common ladybird beetle, Coccinella novemnotata, that
feeds on aphids. (Enlarged 5 rimes)
A, the larva. B, the adult beetle
host of predacious insects. Here are thousands of soft-
bodied creatures, ail herded together, and each tethered
to one spot bv the bristles ofits beak thrust deep into the
tissues of t]e plant--a pot-hunter's paradise, trulv.
Consequently, the placid lires of the aphids bave many
interruptions, and vast numbers of the succulent creatures
serve onlv as half-wav stages in the food cycle of some
other insect. The alhids have small powers of active
[173]
INSECTS
defense. A pair of slender tubes, the cornicles, projecting
from the rear end of the body, eject a sticky liquid which
the aphids are said to smear on the faces of attacking
insects; but the ruse at best probably does hot give much
protection. Parthenogenesis and large families are the
principal policies by which the aphids insure their race
against extinction.
The presence of "evil" in the world has always been a
thorn for those who would preserve their faith in the idea
of beneficence in nature. The irritation, however, is hot
Fç. o 3. The aphis-lion, feeding on an aphis held in its jaws
in the flesh but in a distorted growth of the mind, and
consequently may be alleviated by a change of mental
attitude. The thorn itself, however, is real and can hot
be explained away. Beneficence is hot a part of the
scheme by which plants and animais have attained
through evolution their present conditions and relations.
On the other hand, there are hot good species and bad
species; for every creature, including ourselves, is a thorn
to some other, since each attacks a weaker that may
contribute to its existence. There are many insects that
destroy the aphids, but these are "enemies" of the aphids
only in the sense that we are enemies of chickens and of
cabbages, or of any other thing we kill for food or other
purposes.
[ 7«1
PLANT LICE
Recognizing, then, that evil, like everything else, is a
marrer of relativity and depends upon whose standpoint
it is from which we take our view, it becomes only a par-
donable bias in a writer if he views the subject from the
standpoint of the heroes of his story. With this under-
standing we may note a few of the "enemies" of the
aphids.
Everybody knows the "ladybirds," those little oral,
hard-shelled beetles, usually of a dark red color with
black spots on their rounded backs (Fig. Io B). The
female ladybirds, or better, lady-beetles, lay their orange-
colored eggs in small groups stuck usually to the under
surfaces of leaves (Fig. 132 B) and in the neighborhood
of aphids. When the eggs hatch, they give forth, hot
ornate insects resembling lady-beetles, but blackish little
beasts with thick bodies and six short legs. The young
creatures at once seek out the aphids, for aphids are
their natural food, and begin ruthlessly feeding upon
them. As the young lady-beetles mature, they grow
even uglier in form, some of them becoming conspicu-
ously spiny, but their bodies are variegated with areas of
brilliant color- red, blue, and yellow--the pattern differ-
ing according to the species. A common one is shown at
A of Figure lO2. When one of these miniature monsters
becomes full-grown, it ceases its depredations on the
aphid flocks, enters a period of quietude, and fixes the
rear end of its body to a leaf by exuding a glue from the
extremity of its abdomen. Then it sheds its skin, which
shrinks down over the body and forms a spiny mat ad-
hering to the leaf and supporting the former occupant
by only the tip of the body (Fig. 132 E). With the
shedding of the skin, the insect has changed from a larva
to a pupa, and after a short rime it will transform into a
perfect lady-beetle like its father or mother.
Another little villian, a remarkably good imitation of a
small dragon (Fig. lO3) , with long, curved, sicklelike
jaws extending forward from the head, and a vicious rem-
[175]
INSECTS
F...__..¢.., « perament to match,
' -"--- '>'..//x is. also a common.
/  y trequenter ot the
///ff/  / aphid colonies and
Vffffl levies a toll on the
/////ï{ lives of the meek
o/// k B .d h¢lplCs i.s¢cs.
& ç This marauder is
0   well named the
apkis-lion. He is the larva of a gentle,
harmless creature with large pale-green
lacv wings and brilliant golden eyes
(F@ m4A). The parent femmes
show a remarkable prescience of the
nature of their oflpring, lr they sup-
port their eggs on the tips of long
threadlike
FIa. Io4. Thegolden-
eye, Chrysopa, the par- stalks, tlSU-
ent of the aphis-lion, allyattached
and its eggs tO the under
A, the adult insect. B,
a group of eggs sup- surfaces of
ported on long thread- leaves (B).
like stalks on the under
surface of a leaf The device
seems to be a
scheme for preventing the first
of the greedy brood that will
hatch from devouring its own
brothers and sisters still in their
eggs.
Wherever the aphids are
crowded there is almost sure
to be seen crawling among
them soft grayish or green
wormlike creatures, mostly less
than a quarter of an inch in
length. The body is legless and
tapers to the forward end,
FIG. o 5. A larva ofa syrphus
fly feeding on aphids
[ 761
PLANT LICE
which has no distinct head but from which is protruded
and retracted a pair of strong, dark hooks. Watch one
of these things as it creeps upon an unsuspecting aphid;
with a quick movement of the outstretched forward end
of the body it makes a swing at the fated insect, grabs
it with the extended hooks, swings it aloft kicking and
struggling, and relentlessly sucks the juices from its
body (Fig. o5). Then with a toss it flings the shrunken
skin aside, and repeats the attack on another aphid. This
heartless blood-sucker is a maggot, the larva of a fly
(Fig. o6) belonging to a family called the Syrphidae.
The adult files of this family are entirely harmless, though
FIG. 106. Two common species of syrphus flies whose larvae feed on aphids.
(Enlarged about 3¼ rimes)
A, .411ograpta obliqua. B, OEyrphus americana
some of them look like bees, but the females of those
species whose maggots feed on aphids know the habits
of their offspring and place their eggs on the leaves where
aphids are feeding. One of them may be seen hovering
near a well-infested leaf. Suddenly she darts toward
the leaf and then as quickly is off again; but in the moment
of passing, an egg has been stuck to the surface right
in the midst of the feeding insects. Here it hatches
where the young maggot will find its prey close at hand.
In addition to these predacious creatures that openly
and honestly attack their victims and eat them alive,
the aphids have other enemies with more insidious methods
of procedure. If you look over the aphid-infested leaves
[ 77]
INSECTS
Fm. fo 7. A dead potato
aphis that has contained a
parasite, which when adult
escaped through the door cut
in the back of the aphis
home. The guest that so
ravishes its protector is
the grub of a small wasp-
like insect (Fig. mS) with
a long, sharp ovipositor
by means of which it
thrusts an egg into the
body of a living aphid
Fro. mS. .4phMius, a coin-
mon small wasplike parasite of
aphids
on almost any plant, you will
most likely note here and there
a much swollen aphid of a brown-
ish color. Closer examination
reveals that such individuals are
dead, and man)' of them have a
large round hole in the back,
perhaps with a lid standing up
from one edge like a trap door
(Fig. o7). These aphids have
not died natural deaths; each
has been ruade the involuntary
host of another insect that con-
verted its body into a temporary
Fro. 9. A female .4phidius inserting an
egg into the body of a living aphis, where
the egg hatches; the larva grows to ma-
turity by feeding in the tissues of the
aphis. (From Webster)
IFig. 1o9). Here the egg hatches
and the young grub feeds on
the juices of the aphid until it
is itself full-grown, bv which
rime the aphid is exhatsted and
dead. Then the grub slits open
the lower wall of the hol]ow
corpse and spins a web between
the lips of the opening and
against the surface of the leaf
below, which attaches the aphid
shell to the support. Thus se-
cured, the grub proceeds to give
[178]
PLANT LICE
its gruesome chamber a lining of silk web; which done, it
lies down to test and soon changes to a pupa. After a
short rime it again transforms, this rime into the adult
of its species, and the latter cuts with its jaws the hole in
the back of the aphid and emerges.
In other cases, the dead aphid does hot test fiat on
the leaf but is elevated on a small mound (Fig. l IC)A).
Such victims have been inhabited by the grub of a re-
lated species, which, when full-grown, spins a fiat cocoon
beneath the dead body of its host, and in this inclosure
undergoes its transformation. The adult insect then
cuts a door in the side of the cocoon (B), through which
it makes its exit.
Insects that usurp the bodies of other insects for their
own purposes are called parasites. Parasites are the
FIc. I o. Aphids parasitized by a parasite that makes a cocoon beneath
the body of the aphis, where it changes to a pupa and, when adult,
emerges through a door cut in the side of the cocoon
worst enemies that insects have to contend against; but
reallv they do hot contend against them in most cases,
except in the way characteristic of insects, which is to
insure themselves against extermination by the number
of their offspring. The aphid colonies are often, how-
ever, greatly depleted during a season favorable to the
predacious and parasitic insects that attack them; but no
species is ever annihilated by its enemies, for this would
mean starvation to the next year's brood of the latter.
The laws of compensation usually maintain a balance
[ I79]
INSECTS
in nature between the procreative and the destructive
forces.
The insect parasites and predators of other insects in
general comprise a class of insects that are most beneficial
to us bv reason of their large-scale destruction of species
injurious to our crops. But, unfortunately, parasites as
a class do hot respect our classification of other creatures
into harmful and useful species. I]ven as some predator
is stalking its prey, another insect is likely to be shadowing
it, awaiting the chance to inject into its bodv the egg
which will mean finallv death to the destroyer. lmmature
insects are often fOtllid in a sluggish or half-alive condi-
tion, and an internal examination of their bodies usually
reveals that thev are occupied bv one or more parasitic
larvae. A larva of anv of the lady-beetles, for example,
is frequently seen attacled to a leaf for pupation (Fig. 11 ),
which, instead of transforming to a pupa, remains inert
and soon becomes a lifeless form, though still adhering
to the ]eaf and bent in the attitude that the pupa would
assume. In a short time there issues through the dried
skin a parasite, giving evidence of the fate that has be-
(allen the unfortunate larva; even if the usurper is hot
seen, the exit hole in the larval skin bears witness to his
former occupancy and escape.
And the parasites themselves, do they lead unmolested
lives? Are thev the final arbiters of lire and death in the
insect world? if vou are fortunate sometime while study-
ing aphids out-of'-doors, vou may see a tiny black mite,
no bigger than the small;est gnat, hovering about an in-
fested plant or darting uncertainlv from one leaf to
another, with the air of searching for something but hot
knowing just where to look. You would probably suspect
the intruder of being a parasite seeking a chance to place
an egg in the bodv of an aphid; but here she hovers over
a group of fat lice without selecting a victim, then per-
haps alights and rtlns about on the leaf nervously and
intensely eager, still finding nothing to her choice. Her
[ 8o]
PLANT LICE
senses must be dull, indeed, if it is aphids that she wants.
Do not lose sight of ber, however, for ber attitude bas
changed; now she certainly bas ber eye upon something
that holds ber attention, but the object is nothing other
than one of those swollen parasitized aphids. Yet she
excitedly runs up toit, feels it, grasps it, mounts upon
it, examines it ail over. Evidently she is satisfied. She
dismounts, turns about, backs her abdomen against the
inflated mummy; now
out cornes the swordlike .',,t/.
ovipositor, and with a
thrust it is sunken into
the already parasitized
aphid. Two mmu tes
later her business is
ended, the ovipositor is
withdrawn, once morè
sheathed, and the insect
is off and awav.
This tiny creature is a
hyperparasite, which is to
say, a parasite of a para-
site. In the act just wit-
Fro. III. A parasitized larva of a lady-
bird beetle, and one of the parasites
The larva of the beetle has attached itself
to a leaf preparatory to pupation, but has
hot changed to a pupa because of the
parasites within it. Above, one of the
parasites, which escaped from the beetle
larva through a hole if cut in the skin of
the latter
nessed she, too, has thrust
an egg into the aphid,
but the grub that will
hatch from it will devour
the parasitic occupant
that is alreadv in pos-
session of the aphid's
skin. There are also parasites of hyperparasites, but the
series does hOt go on "ad infinitum" as in the old rhyme,
for the limitation of size must intervene.
CHAPTER Vil
THE PERIODICAI. CICADA
]T iS to be observed, in most of our human affairs, that
we give greatest acclaim to the spectacular, and, further-
more, that when once a hero bas delivered the great thrill,
all his acts of everyday lire acquire headline values. Thus
a biographer may run on at great length about the petty
details in the lire of some great person, knowing well that
the public, under the spell of hero worship, will read with
avidity of things that would make but the dullest plati-
tudes if told of anv undistinguished mortal. Therefore,
in the following history of out (amous insect, universally
known as the "seventeen-year locust," the writer does hot
hesitate to insert marrer that would be dry and tedious
if given in connection with a commonplace creature.
lMost unfortunate it is, now, that we are compe]led to
divest our hero of his long-worn epithet of "seventeen-year
locust," and to present him in the disguise of his true
patronymic, which is cicada (pronounced sî-ka'-da). In
a scientific book, however, we must bave full respect for
the proprieties of nomenclature; and since, as already
explained in Chapter I, the naine "locust" belongs to
the grasshopper, we can hot continue to designate a cicada
by this terre, for so doing would but propagate confusion.
Moreover, even the praenomen of "seventeen-year" is
misleading, for some of the members of the species bave
thirteen-year lires. Entomologists, therefore, bave re-
christened the "seventeen-year locust" the periodical
cicada.
The cicada family, the Cicadidae, includes many species.
[8]
THE PERIODICAL CICADA
of cicadas in both the New World and the Old, and some
of them are more familiar, at least by sound, than our
periodical cicada, because hot only are the males noto-
riously musical, but they are to be heard every year (Fig.
2). The cicadas of southern Europe were highly es-
teemed by the ancient Greeks and Romans for their song,
and they were often kept in cages to furnish entertainment
FIG. II. One of the common annual cicadas whose loud song is
heard every year through the later part of the summer
with their music. The Greeks called the cicada tettix,
and Aesop, who always found the weak spot in every-
body's character, wrote a fable about the tettix and the
ant, in which the tettix, or cicada, after having sung ail
summer, asked a bite of food from the ant when the chill
winds of coming winter found him unprovisioned. But
the practical ant heartlessly replied, "Well, now you can
dance." This is an unjust piece of satire because the
moral is drawn to the disparagement of the cicada.
Human musicians have learned their lesson, however, and
sign their contracts with the box-office management in
advance.
[ I83]
INSECTS
In the United States there are numerous species of
"annual" cicadas, so called because they appear every
year, but their life histories are hot actually known in
most cases. These species are called "locusts," "harvest
files," and "dog-day cicadas" (Fig. I I2). They are the
insects that sit in the trees during the latter hall of sum-
mer and make those long shrill sounds that seem to be
the natural accompaniment of hot weather. Some give
a rising and falling inflection to their song, which re-
sembles zwing, zwing, zwing, zwing, (repeated in a long
series); others make a vibratory rattling sound; and still
others utter just a continuous whistling buzz.
During the interval between the times of the appear-
ancê of the adult cicadas, the insects live underground.
The periodical cicada comprises two faces, one of which
lives in its subterranean abodes for most of seventeen
years, the other for most of thirteen years. Both faces
inhabit the eastern part of the United States, but the
longer-lived race is northern, and the other southern,
though their territories overlap. Most of out familiar in-
sects complete their life cycle in a single year, and many
of them produce two or more generations every season.
For this reason we marvel at the long life of the periodical
cicada, l'et there are other common insects that normally
require two or three years to reach maturity, and certain
beetles bave been known to live for twenty years or more
in an immature stage, though under conditions adverse
for transforming to the adult.
Throughout the period of their underground lire the
cicadas bave a form quite different from that which they
take on when they leave the earth to spend a brief period
in the trees. The form of the young periodical cicada
at the time it is ready to emerge from the ground is shown
in Plate 5- It will be seen that it suggests one of those
familiar shells so often found clinging to the trunk of a
tree or the side of a post. These shells, in fact, are the
empty skins of young cicadas that bave discarded their
[ I84]
PLATE 5
The mature nymph of the periodical
cicada in the form in which it leaves the
ground to transform to the wivged adult
after a subterranean lire of nearly
seventeen vears
THE PERIODICAL CICADA
earthly form for that of a winged insect of the upper world
and sunshine, though the skins_ ordinarily seen are those of
the annual species.
The cicada undergoes a striking transformation from
the young to the adult, but it does so directlv and not by
means of an intervening stage, or pupa. "'he young of
an insect that transforms directly is termed a n.vmph by
most American entomologists. The last nymphal stage
is sometimes called a "pupa," but it is hot properly so
designated.
The life of the periodical cicada stirs our imagination
as that of no other insect does. For years we do not see
the creatures, and then a springtime cornes when countless
thousands of them issue from the earth, undergo their
transformation, and swarm into the trees. Now, for
several weeks, the very air seems swayed with the mo-
notonous rhythm of their song, while the business of ma-
ring and egg-laying goes rapidly on; and soon the twigs of
trees and shrubs are everywhere scarred with slits and
punctures where the eggs have been inserted. In a few
weeks the noisy multitude is gone, but for the rest of the
season the trees bear witness to the busy throng that so
briefly inhabited them by a spotting of their foliage with
masses of brown and dying leaves where the punctured
stems have broken in the wind. The young cicadas that
hatch from the eggs later in the summer silently drop to
the earth and hastily bury themselves beneath the sur-
face. Here they lire in solitude, seldom observed by
creatures of the upper world, through the long period of
their adolescent years, only to enjoy at the end a few
brief weeks of life in the open air in the fellowship of
their kind.
T NYMPHS
Of the underground lire of the periodical cicada we
still know very little. The fullest account of the history
of this species is that given by Dr. C. L. Marlatt in his
lSsl
INSECTS
Bulletin, Tte Periodical Cicada, published by the United
States Bureau of Entomology in I9O 7 . Doctor Marlatt
describes six immature stages of the periodical cicada
between the egg and the adult.
The young cicada that first enters the ground is a
minute, soft-bodied, pale-skinned creature about a twelfth
of an inch in length (Fig. 126). The body is cylindrical
and is supported on two pairs of legs, the front legs being
the digging organs; the somewhat elongate head bears a
pair of small dark eyes and two slender, jointed antennae.
At no stage has the cicada _jaws like those of the grass-
hopper; it is a sucking insect, related to the aphids, and
is provided with a beak arising from the under surface
of the head, but when hot in use the beak is turned back-
ward between the bases of the front legs. Throughout
the period of its underground life, the cicada subsists
on the sap of roots.
During more than a vear the young cicada retains ap-
proximately the form it'has at hatching, though the body
changes somewhat in shape, principally by an increase
in the size of the abdomen (Fig. 13). According to
Doctor Marlatt, a nymph of the seventeen-year race first
Fro. 113. Nymph of the periodi-
cal cicada in the first stage, about
 8 months old, enlarged  5 rimes.
(From Marlatt)
sheds its skin, or molts, some-
rime during the first two or
three months of the second
vear of its lire.
In its second stage it be-
cornes a little larger and is
marked by a change in the
structure of the front legs,
the terminal foot part of
each being reduced to a
mere spur and the fourth
section being developed into
a strong, sharp-pointed pick which forms a more efficient
organ for digging. The second stage lasts nearly two
years; then the creature molts again and enters its th}rd
1861
THE PERIODICAL CICADA
stage, which is about a vear in length. In the fourth
stage, which lasts perhaps three or four years, the nymph
(Fig. 4) shows distinct wing pads on the two wing-
bearing segments of the
thorax. In the fifth stage
the insect, sometimes now
called a "pupa," takes on
the form it has when it
finally emerges from the
earth; its front feet are
restored and its wing
pads are well developed,
but it has entirelv lost its
small nymphai eyes.
Once more, before its
long underground sen-
FIG. 114. Nymph of the periodical
cicada in the fourth stage, about  years
old, enlarged OEvd times. (From Marlatt)
tence is up, the nymph molts, and enters the sixth and
last stage of its subtelranean lire. When mature (Plate 5)
it is about an inch and a quarter in length, thick-bodied,
and brown in color; it appears to have a pair of bright-red
eyes on the head, but these are the eyes of the adult
inside showing through the nymphal skin.
According to the investigations of Doctor Marlatt, the
nymphs of the periodical cicada do not ordinarily burrow
into the earth below two feet, and most of them are to be
round at depths varying from eight to eighteen inches.
However, there are reports of their having been discovered
ten feet beneath the surface, and they have been known
to emerge from the floors of cellars at the time of trans-
formation to the adult stage. There is no evidence that
the insects, even when present in great numbers in the
earth, do any appreciable damage to the vegetation on
the roots of which they feed.
Some time before the mature nymphs emerge from the
ground, probably in April of the last year of their lives,
the insects corne up from their subterranean burrows and
construct a chamber of varying depth just below the
[187]
INSECTS
'lç. I 1_. Outlines of plaster casts of underground resting chambers of the
rnature nymph of the periodical cicada (about one-half natural size)
[88]
THE PERIODICAL CICADA
surface. A good idea of the size and shape of these cham-
bers may be obtained bv filling the opened holes with a
mixture of plaster of Paris in water, letting the plaster
harden, and then digging up the casts. Figure I t5 shows
castsofa number ofchambers madein this way. Some, it
is seen, are mere cups about an inch in depth, but most of
them are long and narrow, descending several inches into
the ground, the longest being six inches or more in depth.
The width is usually about five-eighths of an inch. Ail
the chambers bave a distinct enlargement at the bottom,
and most of them are slightly widened at the top. The
upper wall of each is separated from the surface by a
laver of undisturbed soil about hall an inch in thick-
ness, which is hot broken until the insect is ready to
enlerge.
The shafts are seldom straight, their courses being
more or less tortuous and inclined to the surface, as the
miner had to avoid roots and stones obstructing the
vertical path. The interior contains no débris of any
kind, and the walls are smooth and compact. Below
each chamber there is always evidence of a narrower
burrow going irregularly downward into the earth, but
this tunnel is filled to the chamber floor with black granu-
lar earth. The burrows examined bv the writer near
Washington in 99 were dug through compact red clay,
and the lower tunnels here ruade a distinct black path
through the red of the surrounding clay, where some
could be followed for a considerable distance. The black
color of the earth filling the tumels was possibly due to
an admixture of fecal matter.
The chambers, as we bave noted, are closed at the top
until the cicada is readv to emerge. The largest chambers
are manv times the btilk of the nymph in volume, and it
becomes, then, a question as to what the insect does with
the material it removed in making a hole of such size. It
seems improbable that it could have been carried down
into the lower tunnel, for this would be filled with its own
[ 891
INSECTS
débris. The insects thernselves will give an answer to
the question if several of thern are placed in glass tubes
and covered with earth; but, to understand the cicada's
technique, we must first study the rnechanisrn of its
digging tools, the front legs.
The front leg of a rnature cicada nyrnph (Fig. J x6 A) is
Fro. 6. The digging organ, or front
leg, of the mature cicada nymph
A, right le[g, inner surface (4 times natural
size). B, the tarsus (Tar) bent inward at
right angles to the tibia (Tb), the posi-
tion in which it is used as a rake
Cx, basal joint or coxa; Tf, trochanter; F,
retour; Tb, tibia; Tar, tarsus, with two
terminal daws
cornposed of the sarne
parts as anv other of its
legs. The (hird segment
frorn the base, which is
the.femur (F), is large
and swollen, and has a
pair of strong spines and
a cornb of srnaller ones
projecting frorn its lower
edge. The next segment
is the tibia (Tb). It is
curved and terrninates
in a strong recurved
point (B). Finally, at-
tached to the inner sur-
face of the tibia, well up
frorn its terminal point,
is the slender tarsus
(Tar). The tarsus can
be extended beyond the
tibial point when the insect is walking or clirnbing, but
can also be turned inward at a right angle to the latter,
as shown at B, or bent back against the inner surface of
the tibia.
Let us now return to the insects in the earth-filled
tubes, where they are industriously at work. It will be
seen that they are using the curved, sharp-pointed tibiae
as picks with which to loosen the earth, the tarsi being
turned back and out of the way. The two legs, working
alternately, soon accurnulate a srnall rnass of loosened
rnaterial in front of the insect's body. Now there is a
[ J9 o ]
THE PERIODICAL CICADA
cessation of digging and the tarsi are turned forward at
right angles to the tibiae to serve as rakes (Fig. J J6 B).
The mass of earth pellets is scraped in toward the body,
and -here cornes the important part, the cicada's special
technique--the little pile of rakings is grasped by one
front leg between the tibia and the femur (.Fig. 6 A,
Tb and F), the former closing up against the spiny margin
of the latter, the leg strikes forcibly outward, and the
mass of loosened earth is pushed back into the surrounding
earth. The process is repeated, first with one leg, then
with the other. The miner looks like a pugilist training
on a punching bag. Now and then the worker stops and
rubs his legs over the protruding front of the head to
clean them on the rows of bristles which cover each side
of the face. Then he proceeds again, clawing, raking,
gathering up the loosened particles, thrusting them back
into the wall of the growing chamber. His back is firmly
pressed against the opposite side of the cavitv, the middle
legs are bent forward uhtil their knees are aimost against
the bases of the front legs, their tibiae lying along the wing
pads. The hind legs keep a normal position, though
held close against the sides of the bodv.
From what we know of the cicada's spring habits
underground, we can infer that the nymphs construct
their chambers on their arrival near the surface during
April, and that, when the chambers are completed, the
insects wait within for the signal to emerge and trans-
form into the adult. Then they break through the thin
caps at the surface and corne out. t would be difficult
to explain how thev know when they are so near the top
of the ground, and" whv some construct ample chambers
several inches deep whle others make mere cells scarcely
larger than their bodies. Do they burrow upward till the
pressure tells them that the surface is only a quarter of
an inch or so away, and then widen the débris-filled
tunnel downward? Evidently hot, because the chamber
walls are ruade of clean, compacted clay in which there
I J9  ]
I NSECTS
is no admixture of the blackened contents of the burrows.
It is unlikely, too, that they base their judgments on a
sense of temperature, because their acts are hot regulated
by the nature of the season, which, if early or late, would
fool them in their calculations.
Early in the spring, before the proper emergence season,
cicada nymphs are often round beneath logs and stones.
This is to be expected, for, to the ascending insect, some-
thing impenetrable has blocked the way, and there is
nothing to tell it that it has already reached the level of
the surface.
A more curious thing, often observed in some localities,
F1G. i17. Earthcn turrcts somctimes.
erected by the nymphs of the periodcal
cicada as continuations frorn their under-
ground chambers. One cut open showing
the tubular cavity within. (From photo-
graph by Marlatt)
is that the insects some-
rimes continue their
chambers up above the
surface of the ground
within closed turrets of
mud from two to several
inches in height (Fig.
117). At certain places
these cicada "huts" have
been reported as occur-
ring m great numbers;
and it bas been supposed
that they ma}" be built
wherever there is some-
thing about the nature of
the soli that the insects
do hot like, the earth
being perhaps too damp,
for they are frequently
round where the ground
is unusually wet. On the other hand, the turrets have
been observed in dry situations as well, and towers and
holes flush with the surface frequently occur intermingled.
The writer has had no opportunity of studying the cicada
turrets, but a most interesting description of them is given
[Igal
I'LXTE 6
The cicada just after emergence flore the nymphal
skin. (Enlarged two-thirds)
THE PERIODICAL CICAI)A
by Dr. J. A. 1.intner in his Tzvel.[th Report on the lnsects o.[
.Vew '0rk, published in ,897. l)r. l.intner savs the
turrets are constructed bv the nymphs with soif'pellets
of clay or mud brought up from below and firmly pressed
into place, and he records an observation on a nymph
caught at work with a pe]let of mud in its claws. \Ve
mav infer, then, that the cicada's style of work as a
mason is only a modification of its work'ing methods as a
miner, but it appears that no one bas vet actuallv watched
the construction of one of the turrets. At emergence
time the towers are opened at the top and the insects corne
forth as thev would from an ordinarv chamber beneath the
level of the ground.
"I'H E "I'RANS FORMATION
The period of emergence for most of the cicadas of the
northern, or seventeen-year, race is the latter part of
lav. The rime of their appearance over large areas is
much more nearlv uniform than with most other insects,
which show a wide variation according to temperature as
determined bv the season, the elevation, and the latitude.
Nevertheless," observations in different localities show
that the cicada, too, is influenced by these conditions.
In the South, members of the thirteen-vear race may
emerge even a month earlier, the tirst incividuals of the
southernmost broods appearing in the latter part of
April.
Bv some feeling of impending change the rnature
nymph, waiting in its chamber, knows when the time of
transformation is at hand. Somehow nature regulates
the event so that it will happen in the evening, but, once
the hour has corne, no time is to be lost. The nymph
must break out of its cell, tind a suitable molting site
and one in accord with the traditions of its race, and there
fix itself by a tirm grip of the tarsal claws. At the be-
ginning of the principal emergence period large numbers
of the insects corne out of their chambers as early as
[ 93J
INSECTS
rive o'clock in the afternoon; but after the rush of the
first few days hot many appear belote dusk.
It is difficult to catch a nymph in the very act ofmaking
its exit from the ground, and apparently no observations
bave been recorded on the manner of its leaving. Do the
insects leisurely open their doors some time in advance
of their actual need and wait below till the proper hour,
or do they break through the thin caps ofearth and emerge
at once? Digging up many open chambers revealed a
living nymph in only one. Another issued from one of
several dozen holes filled with liquid plaster for obtaining
casts. Add to this the fact that great numbers of fresh
holes are to be seen every morning during the emergence
season, and the evidence would appear to indicate that
the insects open their doors in the evening and corne out
at once. Only one chamber was round in the daytime
partly opened.
If the insects are elusive and wary of being spied
upon as thev make their début into the upper world, a
witness of tleir subsequent behavior does hot embarrass
them at ail. However, events are imminent; there is
no time to waste. The crawling insects head for anv
upright object within their range of vision- a tree is the
ideal goal if it can be attained, and since the creatures
were born in trees there is likely tobe one near by. Yet
it ffequently happens that trees in which many were
hatched have been since cut down, in which case the
returning pilgrims must make a longer journey perhaps
than anticipated. But the transformation can hot be
delayed; if a tree is hot accessible, a bush or a weed, a
post, a telegraph pole, or a blade of grass will do. On
the trees some get only so far as the trunk, others attain
the branches, but the mob gets out. upon the leaves.
Thotlgh thousands emerge almost simultaneously, thev
have not ail been timed alike. Some have but a few
minutes to spare, others can travel about for an hour or
so before anything happens.
[ 941
THE PERIODICAL CICADA
The external phase of transformation, more strictly
the shedding of the last nymphal skin, has been many
times observed. It is nothing more than what ail insects
do. But the cicada is notorious because it does the thing
in such a spectacular way, almost courting publicity
where most insects are shy and retiring. As a conse-
quence the cicada is famous; the others are known only
to prying entomologists.
Let us suppose now that our crawling nymph has
reached a place that suits it, say on the trunk of a tree,
or better still on a piece of branch provided for it and
taken into a lighted room where its doings can be more
clearly observed. Though the insects choose the evening
for emergence, they are hot bashful at ail about changing
their clothes in the glare of artificial light. The progress
of this performance is illustrated bv Figure I i8. The
first drawing shows the nymph stiil creeping upward;
but in the next (2) it has corne to rest and is cleaning
its tront feet and claws on the brushes of its face, just
as did those confined to the glass tubes to give a demon-
stration of their digging methods. The front feet done,
the hind ones are next attended to. First one and then
the other is slowlv flexed and then straightened back-
ward (3) while the foot scrapes over the side of the ab-
domen. Several times these acts are repeated calmly
and deliberately, for it is an important thing that the
claws be well freed from any particles of dry earth that
might impair their grip on the support. /t last the
toilet is completed, though the naiddle feet are always
neglected, and the insect feels about on the twig, grasp-
ing now here, now there, till its claws take a firm hold
on the bark. At the saine time it sways the body gently
frona side to side as if trying to settle comfortably for the
next act.
Thirtv-five minutes mav be consumed in the above
preliminaries and there is "next a ten-minute interval of
quietude before the real show begins. Then suddenly
I951
INSECTS
Çl+. I18. Transformation of the periodical cicada from thc mature
nymph to the adult
l 9 6 ]
THE PERIODICAL CICADA
the insect humps its back (4), the skin splits along the
midline of the thorax (.5), the rupture extending forward
over the top of the head and rearward into the first seg-
ment of the abdomen. A creamv white back, stamped
with two _large .let-black spots, now bulges out ((5, 7);
next cornes a head with two brilliant red eyes (8); this is
followed bv the front part of a bodv (9) which bends
backward and pulls out legs and basés of wings. Soon
one leg is free (`'o), then four legs (`'`'), while four long,
glistening white threads pull out of the bodv of the issuing
creature but remain attached to the empty shell. These
are the linings of the thoracic air tubes being shed with
the nymphal skin. Now the bodv hangs back down,
when ail the legs corne free (`'2), and now it sags peril-
ouslv (C') as the wings begin to expand and visiblv
lengthen.
Here another rest intervenes; perhaps twentv-five min-
utes mav elapse, while the sort new creature, like an in-
verted gargoyle supported onlv bv the rear end of its
body, hangs motionless far out "fro{ the split in the back
of the shell. Now we understand whv the nymph took
such pains to get a firm anchorage, for, should the dead
claws give wav at this critical stage, the resulting fall
most probably «ould prove fatal.
The next act begins abruptly. The gargoyle moves
again, bends its bodv upward ("4), grasps the head and
shoulders of the slo'ugh (*'5), and pulls the rear parts
of its bodv free from the gaping skin (,,6). The body
straighten" and hangs downward (`'7)- At last we be-
hold the free imago, hOt ver mature but rapidly assum-
ing the characters of an adult cicada. The new creature
hangs for a while from the discarded shell-like skin,
clinging bv the front and middle legs, sometimes by the
first alone; the hind ones spread out sidewavs or bend
against the body, rarelv grasping the skin. The wings
continue to unfold and lengthen, finallv hang fiat, fullv
formed, but soft and white (`'N). 14ere the creature
[97]
INSECTS
usually becomes restless, leaves the empty skin (I9) , and
takes up a new position several inches away
At this stage the cicada is strangely beautiful. Its
creamy-yellow paleness, intensified by the great black
patches just behind the head and relieved by the pearly
flesh tint of the mesothoracic shield, its shining red eyes,
and the milky, semitransparent wings with deep chrome
on their bases make a unique impression on the mind.
There is a look of unrealitv about the thing, which out of
doors (Plate 6) becomes a ghostlike vision against the
night. But, even as we watch, the color changes; the
unearthly paleness is suffused with bluish gray, which
deepens to blackish gray; the wings flutter, fold against
the back, and the spell is broken--an insect sits in the
place of the vanished specter.
The rest is commonplace. The colors deepen, the grays
become blackish and then black, and after a few hours the
creature bas all the characters of a fully matured cicada.
Early the next morning it is fluttering about, restless to
be off with its mates to the woods.
The time consumed by the entire performance, from
the splitting of the skin (Fig. I  8, 5) to the folding of the
wings above the back (2I), varies with different indi-
viduals, observed at the saine time and under the saine
conditions, from forty-five minutes to one hour and
twelve minutes. Most of the insects bave issued from
the nymphal skins before eleven o'clock at night, but oc-
casionally a straggler may be seen in the last act as late
as nine o'clock the following morning--probably a be-
lated arrival who overslept the night before.
Thus, to the eye, the burrowing and crawling creature
of the earth becomes transfigured to a creature of the air;
vet the visible change is mostly but the final escape of
the mature ingect from the skin of its preceding stage.
Aside from a few last adjustments and the expansion of the
wings, the real change bas been in progress within the
nymphal skin perhaps for years. We do hot truly witness
[ 9 8 ]
THE PERIODICAL CICADA
the transformation; we see only the throwing off of the
shell that concealed it, as the circus performer strips off
the costume of the clown and appears already dressed
in that of the accomplished acrobat.
T ADVLTS
The adult cicada bears the stamp of individuality. In
form he does hOt closely resemble any of out everyday
insects, and he has a personality ail his own; he impresses
us as a "distinguished foreigner in out midst." The body
of the periodical cicada is thick-set (Fig. 119) , the face is
bulging, the forehead is wide, with the eyes set out promi-
nently on each side; from the under side of the head the
short, strong beak projects downward and backward be-
tween the bases of the front legs. The colors are dis-
tinctive but hOt striking. The back is plain black (Plate
7) ; the eyes are bright red; the wings are shiny transparent
amber with strongly marked orange-red veins; the legs
and beak are reddish, and there are bands of the same
color on the rings of the abdomen. Ech front wing is
branded near the tip with a conspicuous dark-brown W.
With both the seventeen-year race and the thirteen-
year race of the periodical cicada there is associated a
small cicada, which, however, differs so little except in
size from the others (Fig. 119) that entomologists gener-
ally regard it as a mere variety of the larger form, the
latter always including by far the greater number of
individuals in any brood.
The male cicada has a pair of large drumheads beneath
the bases of the wings on the front end of the abdomen
(Fig. oEo, Tre). These are the instruments by which
he produces his music, and we will give them more atten-
tion presently. The female cicada has no drums nor other
sound-making organs; she is voiceless, and must keep
silence no matter how much her noisy mate mav disturb
ber peace. The chier distinction of the female is ber
ovipositor, a long, swordlike instrument used for inserting
[ 99]
I N S EC'I'S
the eggs into the twigs of trees and bushes. Ordinarilv the
ovipositor is kept in a sheath beneath the rear halfof the
abdomen, but when in use it can be turned downward
and forward bv a hinge at its base (Plate 7). The oviposi-
tor consists of two
lateral blades, and a
 guide-rail ai»ove. The
blades excavate a cav-
 itv in the wood in-
te; which the eggs
j are passed through
the space between the
blades.
I t was formcrlv sup-
posed that the period-
ical cicada takes no
fod during the brief
Flç. 119. blales of the large and small form
of the periodical cicada (natural size) rime of its adult lire,
but e know from the
observations of .lr. W. T. l)avis, l)r. A. !...Quaintance,
and others and from a studv of the stomach contents ruade
o
bv the writer that the insects do feed abundantlv bv
st'cking the sap from the trees on which thev lire. The
cicada, being a
near relative of
the aphids, has  / 
also, as we have
alreadv noted, a
pierci{ and suck-
in belîk bv which 
it  the
punctures
plant tissues and r,
draws the sap up
toitsmouth. ['n-
like the other
sucking insects v,ç. ,=o.  ,ale of ,e pr,,«a! «iaaa ,i, ,e
wings spread, showing the ribbed sound-producing
that infest plants, organs, or tympana (Tm),on thebaseofthe abdomen
[ 200 ]
THE PERIODICAI. CICADA
however, the cicadas cause no visible damage to the trees
bv their feeding. Perhaps this is because their attack
lasts such a short rime and cornes at a season when the
trees are at their fillest vigor.
The details of the head structure of the cicada and
the exposed part of the beak are shown in Figure
which gives in side view the head of a fully matured
adult, detached from the body by the torn neck mem-
brane (.VMb), with the beak (Bk) extending downward
and backward below. The large eyes (E) project from
the sides of the upper part of the head. The face is
covered bv a large protruding, striated plate (C/p). The
cheek regions are firmed bv a long plate (Ge) on each side
below the eyes; and between each cheek plate and the
striated facial plate is parti)" concealed a narrower plate
(Md). The cicada bas no jaws. lts true mouth is shut
in between the large flap (.tClp), below the striated facial
plate, and the base of the beak.
If the outer parts of the head about the mouth can be
separated, there will be seen within them some other verv
important parts ordinarilv hidden from view. In a
specimen that has been killéd in the act of emerging from
the nymphal skin, when it is still soft, the outer parts are
easilv separated, exposing the structures shown at B of
the saine figure.
It is now to be seen (b'ig. '._ B) that the beak con-
sists of a long troughlike appendage (Lb) suspended from
beneath the back part of the head, having a deep groove
on its front surface in which are normally ensheathed
two pairs of slender bristles (MdB, .ll.vB), of which only
the two of the left side are shown in the figure. In front
of the bases of the bristles there is exposed a large tongue-
like organ which is the hypopharynx (Hph)'). Between
this tongue and the flap hanging from the front of the
face is the wide-open mouth (Mtt), the roof of which (e)
bulges downward and almost fills the mouth cavity.
The wav in which the cicada obtains its liquid food de-
[ 2OI ]
INSECTS
pends upon the finer structure and the mechanism of
the parts before us.
Each one of the second pair of bristles bas a furrow
along the entire length of its inner surface, and the two
F. . The structure f the head and sueklng beak
A, the Bead in side view with the beak (B) in natural
B, the head f an immature adult: the muth
(«) f the su«king pump (soe fig. e), and the tnguelike
the parts f the beak separated, shwing that it is emposed f the labium
(L), inclsing nrmally tw pai f Ing slender bristles (MdB,
one of each pair shown)
a, bridge between base of mandibular plate (Md) and hypopharynx (Hpy);
.lclp, anteclypeus; nt, antenna; Bk, beak; Clp, clypeus e, roof of mouth cavity,
or sucking pump; Ge, gena fcheek plate); Hpy, hypopharynx; Lb, labium; Lin,
labrum; Md, base of mandible; MdB, mandibular bristle; Mth, mouth;
axilla MxB, maxillary bristlei NMb, neck membrane; O, oeelli
bristles, small as they are, are fastened together by inter-
locking ridges and grooves, so that their apposed fur-
rows are converted into a single tubular channel.
the natral position, these second bristles lie in the
sheath of the beak (Fig. ux A) between the somewhat
larger first bristles. Their bases separate at the tip'of
I o ]
THE PERIODICAI. CICADA
the tongue (Hphy) to pass to either side of the latter
organ, but the channel between them here becomes con-
tinuous with a groove on the middle of the forward sur-
face of the tongue. When the mouth-opening is closed,
as it always is in the fully matured insect, the tongue
groove is converted into a tube which leads upward from
the channel between the second bristles into the inner
cavity of the mouth. It is through this minute passage
that the cicada obtains its liquid food; but obviously
there must be a pumping apparatus to furnish the sucking
force.
The sucking mechanism is the mouth cavity and its
muscles. The mouth cavity, as seen in a section of the
head (Fig.  22, Pmp), is a long, oval, thick-walled capsule
having its roof, or anterior wall (e), ordinarily bent inward
so far as almost to fill the cavity. Upon the midline
of the roof is inserted a great mass of muscle fibers
(Pmp:$lcl«) that have their other attachment on the
striated plate of the face (Clp). The contraction of these
muscles lifts the roof, and the vacuum thus created in
the cavity of the mouth sucks up the liquid food. Then
the muscles relax, and the elastic roof again collapses,
but the lower end cornes down first and forces the liquid
upward through the rear exit of the mouth cavity into
the pharynx, a small muscular-walled sac (P]zy) lying
in the back of the head. From the pharynx, the food
is driven into the. tubular gullet, or oesophagus (OE),
and so on into the stomach.
The bases of both pairs of bristles are retracted into
pouches of the lower head wall behind the tongue, and
tapon each bristle base are inserted sets of protractor
and retractor muscle fibers. By means of these muscles,
the bristles can be thrust out from the tip of the beak or
withdrawn, and the bristles of the stronger first pair
are probably the chier organs with which the insect
punctures the tissues of the plant on which it feeds. As
the bristles enter the wood, the sheath of the beak can
INSECTS
be retracted into the flexible membrane of the neck at
i ts base.
One other structure of interest in the cicada's head
should be observed. This is a force pump connected
with the duct (Fig. 2"_, SalD) of the large salivary glands
G/, GI) and used probably for injecting into the wound
of the plant a secretion which perhaps softens the tissues
of the latter as the bristles are inserted. Possiblv the
salira has ,'{lso a
Cl
GI
/VidB"
/VixB"
FIG. 122. Median section of the head and beak of
an aduIr cicada
The sucking pump (Proie) is rhe mouth cavity, the
collapsed roof of which (e) can be lifred like a piston
by rhe large 'muscles (PmpIcls) arising on rhe
clypeus (Clp). The liquid food ascends rhrough a
channel between rhe maxillary brisrles (IxB}, is
drawn into rhe mourh opening (Ith), and pumped
back inro rhe pharynx (Phy), from which if goes inro
rhe oesophagus (OE). A salivary pump (alPmp)
opens af rhe rip of rhe hypopharynx (Hp&v), dis-
charging the secrerion of rhe large glands (GI, GI)
inro rhe beak
digestive action
on the food liquid.
The salivarv
pump (SalPmp)
lies behind the
mouth, and its
duct opens on the
extreme tip of the
tongue, where the
salira can be
driven into the
charme} of the
second bristles.
.lost sucking
sects have two
parallel channe]s
between these
bristles IFig. 9o),
one for taking
food, the other
for ejectingsaliva,
and the cicada
probably bas two
also, though in-
vestigators diff-er
as to whether
there are two or
on}v one.
[ 204]
THE PERIODICAL CICA1)A
The head of the cicada is thus seen to be a wonder(ul
mechanism for enabling the insect to feed on plant sap.
The piercing beak and the sucking apparatus, however,
are characters distinguishing the members of a whole
order of insects, the Hemiptera, or Rhvnchota. This
order includes, besides the cicadas, such "familiar insects
as the plant lice, the scale insects, the squash bugs,
the giant water bugs, the water striders, and the bed
bugs. "Fo the sucking insects properly belongs the naine
"bug," which is hot a svnonwaa of "insect."
It is believed, of course, that the parts of the sucking
beak of a hemipteran insect correspond with the mouth
parts of a biting insect, described in Chapter IV (Fig.
66), but it has been a difficult marrer to determine the
identities of the parts ira the two cases. Probablv the
anterior narrow plate on the side of the cicada's'head
(Fig. 2, .lld) is a rudiment of the base of the true jaw,
or mandible. The first bristles (aldB) are outgrowths
of the mandibular plates, which have become detached
from them and ruade independentlv movable by special
sets of muscles. The second bri'tles (M.vB) are out-
growths of the maxillae, which are otherwise reduced
to small lobes (M.v) depending from the cheek plates
(Ge). The sheath of the beak (Lb) is the labium. We
have here, therefore, a most instructive lesson on the
manner ira which organs mav be ruade over ira form, by
the processes of evolution, "adapting them to new and
often highly special uses.
The abdomen of the cicada is thick, and strongly
arched above, l ts external appearance of plumpness
suggests that it would furnish a juicy meal for a bird,
and birds do destroy large numbers of the insects. Yet
when the interior of a cicada is examined (Fig.  23) , it is
found that almost the entire abdomen is occupied by a
great air chamber! The soft viscera are packed into
narrow spaces about the air chamber, the stomach (&0m)
being crowded forward into the rear part of the thorax.
[ 205 ]
INSECTS
[ =o6 ]
THE PERIODICAL CICADA
The air chamber is a large, thin-walled sac of the tracheal
respiratory system, and receives its air supply directly
through the spiracles of the first abdominal segment.
From the sac are given off tracheal tubes to the muscles
of the thorax and to the walls of the stomach.
Many insects have tracheal air sacs of smaller size,
and the purpose of the sacs in general appears to be that
of holding reserve supplies of air for respiratory pur-
poses. The great size of the air sac in the cicada's abdo-
men, however, suggests that it has some special function,
and it is natural to suppose that it acts as a resonating
chamber in connection with the sound-producing drums.
Yet the sac is as well developed in the female as in the
male. Possibly, therefore, it serves too for giving buoy-
ancy to the insects, for it can readily be seen that if the
space occupied by the sac were filled with blood or other
tissues, as it is in most other insects, the weight of the
cicada would be greatly increased; or, on the other
hand, if the body were contracted to such a size as to
accommodate only its scanty viscera, it would lose
buoyancy through lack of suflîcient extent of surface--
a paper bag crumpled up drops immediately when re-
leased, but the saine bag inflated almost floats in the air.
THE SOUND-PRODUCING ORGANS AND THE SONG
The cicadas produce their music by instruments quite
different from those of any of the singing Orthoptera
--the grasshoppers, katydids, and crickets, described
in Chapter ll. On the body of the male cicada, just
back of the base of each hind wing, as we have already
observed, in the position of the "ear" of the grasshopper
(Fig. 63, Tre), there is an oval membrane like the head
of a drum set into a solid frame of the body wall (Fig.
lzo, Tre). Each drumhead, or tympanum, is a mem-
brane closely ribbed with stiff vertical thickenings, the
number of ribs varying in different species of cicadas
and perhaps accounting in part for the different qualities
[ "-o7 1
INSECTS
of sound produced. In the periodical cicada, the drum-
heads are exposed and are easily seen when the wings
are lifted; ira our other common cicadas each drum lS
concealed by a flap of the body wall.
The sound ruade by ara ordinarv drum is produced by
the vibration of the drumhead that is struck by the
player, but the tone and volume of the sound are given
bv the air space within the drum and by the sympathetic
vibration of the opposite head. The air within the
drum, then, must be in communication with the air
outside the drum, else it would impede the vibration of
the drumheads.
Ail these conditions imposed tapon a drum are met bv
the cicada. The abdomen of the insect, as we have seen,
is largely occupied by a great air chamber (Fig. z3) ,
and the air within the chamber communicates with the
outside air through the spiracles of the first abdominal
segment (ISp). In addition to the two drumheads whose
activity produces the sound, there are two other thin,
taut lmmbranous areas set into oral frames in the lower
side walls of the front part of the abdomen (hOt seen
in the figures). These ventral drumheads have such
smooth and glistening surfaces that they are often desig-
nated the "mlrrors." The wall of the air sac is applied
closely to their inner surfaces, but both membranes are
so thin that it is possible to see through them right into
the hollow of the cicada's bodv. The ventral drum-
heads are hOt exposed externally, however, for they are
covered by two large, fiat lobes projecting back beneath
them from the under part of the thorax.
The cicada does hot beat its drums or play upon thern
with anv external part of its body. When a maie is
"singing," the exposed drumheads are seen to be in very
rapid vibration, as if endowed with the power of auto-
matic movement. An inspection of the interior of the
bodv of a dead speclmen, however, shows that con-
nected with the inner face of each drumhead is a thick
I =og ]
THE PER1OD1CAI. CICADA
muscle which arises below from a special support on the
ventral wall of the second abdominal segment (Figs.
23, I24, Tm.rtlcl). It is by the contraction of these
muscles that the drum membranes are set in motion.
TITI
Trnlcl
A
IT IIT IIIT
Tre- . .Trrdcl
B IS IIS IIiS
FIG. 1:24. The abdomen and sound-making organs of the male periodical
cicada
A, the abdomen cut open from above, exposing the air chamber (HirSc), and
showing the great tympanal muscles (TmMcl) inserted on the tympana (Tre).
The arrows indicate the position of the first spiracles opening into the air chamber
(see fig. 123, ISp)
B, inner view of right hall of first and second abdominal segments, showing the
ribbed tympanum (Tre), and the muscles that vibrate it (TmMcl)
AirSc, air chamber; DMcl» dorsal muscles; IS, IlS, IIIS, sternal plates of first
three abdominal segments; ISp, first abdominal spirade; IT, liT, IIIT, tergal
plates of first three abdominal segments; ,, tergal plate of third thoracic seg-
ment; Trn, tympanum; TmMcl, tympanal muscle; I/a, base of hind wing; IMcl,
ventral muscles
But a muscle pulls in onlv one direction; the drum muscles
produce directlv the inward stroke of the drumhead
membranes; the return stroke results flore the outward
convexitv and the elasticitv of the heads themselves
and the stiff ribs in their wal]s.
When a cicada starts its music, it lifts the abdomen a
little, thus opening the space between its ventral drum-
[ 2o9 ]
INSECTS
heads and the protecting flaps beneath, and the sound
cornes out in perceptibly increased volume. There can
be little doubt that the air chamber of the body andthe
ventral membranes are important accessories in the
sound-producing apparatus. Living cicadas are often
found with hall or more of the abdomen broken off, leav-
ing the air sac open to the exterior. Such individuals
may vibrate the drumheads, but the sound produced is
weak and entirely lacks the quality of that ruade by the
perfect insect.
Wherever the periodical cicada appears in great num-
bers, the daily choruses of the mmes leave an impression
long remembered in the neighborhood; and, curiously,
the sound appears to become increasingly louder n
retrospect, until, after the lapse of years, each hearer is
convinced it was a deafening clamor that almost deprived
him of his senses. Fortunately the cicadas are day-
time performers and are seldom heard at night. The
song of the periodical species has no resemblance to the
shrill, undulating screech of the annual cicadas so coin-
mon every summer in August and September. Ail the
notes of the more common large form of the seventeen-
year race are characterized by a burr sound, and at
least four different utterances may be distinguished; the
quality of three of the notes probably depends on the
age of the individual insect, the fourth is an expression
of fright or anger.
The simplest notes to be heard are sort purring sounds,
generally ruade by solitary insects sitting low in the
bushes, probably individuals that have but recently
emerged from the ground. The next is a longer and
louder note, characterized by a rougher burr, lasting about
rive seconds, and always given a falling inflection at the
close. This sound is the one popularly known as the
"Pharaoh" song, because of a fancied resemblance to
the naine if the first syllable is sufficiently prolonged and
the second allowed to drop off abruptly at the end. It
[ 2.10 ]
THE PERIODICAI. CICADA
is repeated at intervals of from two to rive seconds, and
is given always as a solo by individuals sitting in the
bushes or on lower branches of the trees. Males singing
the Pharaoh song, therefore, are easily observed in the
act of performing. With the beginning of each note, the
singer lifts his abdomen to a rigid, horizontal position,
thus opening the cavity beneath the lower drumheads
and letting out the full volume of the sound. Toward the
end of the note, the abdomen drops again to the usual
somewhat sagging position, appearing thus to give the
abrupt falling inflection at the close.
The grand choruses, bv which the periodical cicada is
chieflv known and remembered, are given by the fullv
matured mmes of the swarm, always high in the trees
where the singers may seldom be closely observed while
performing. The individual notes are prolonged bur-r-r-r-
like sounds, repeated ail day and day after day, but ail
single voices are blended and lost in the continuous hum
of the multitude.
The fourth note of the larger form of the cicada is
uttered bv males when they appear to be surprised or
frightened'. On such occasions, as the insect darts
away, he makes a loud, rough sound, and the same note
is often uttered when a maie is picked up or otherwise
handled.
"l'he notes of the small form of the seventeen-year race
of the cicada have an entirely different character from
those of his larger relative. The regular song of the little
toiles much more resembles that of the annual summer
cicadas, thmgh it is hot so long and is less continuous
in tone. It opens with a feu, short chirps; then follows
a series of strong, shrill sounds like z'ing, za:'ig, zaaing,
and so on, closing again with a number of chirps. The
whole song lasts about fifteen seconds. Several of these
males kept in cages for observation sang this song re-.
peatedly and no other. It is common out of doors, but
alwavs heard in solo, never in chorus. When handled
[211 ]
I NSECTS
or otherwise disturbed, the small males utter a succession
of sharp chirps very suggestive of the notes of some
miniature wren angrily scolding at an intruder. Never
does the small form of the cicada utter notes having the
bz«rr tone of those of the larger species, and the vocal
differences of the two varietms are strikingly evident
when several males of both kinds are caged together.
When disturbed, each produces his own sound, one the
burr, the other the chirp; and there is never an)" sugges-
tion of similarity or of gradation between them.
F, GG .AY1NG
The cicadas la)" their eggs in the twigs of trees and
shrubs and frequently in the stalks of deciduous plants.
They show no particular choice of species except that
conifers are usually avoided.
The eggs are not stuck into the wood at random, but
are carefully placed in skillfully constructed nests which
the female excavates in the twigs with the blades of ber
ovipositor (Plate ,q). These nests are perhaps always
on the under surfaces of the twigs, unless the latter are
vertical, and usually there are rows of from half a dozen
to twentv or more of them together.
Egg laying begins in the early part of June, and by
the tenth of June it is at its height. The female cicadas
can easily be watched at work, taking flight only from
actual interference. They usually select twigs of last
year's growth, but often use older ones or green ones of
the saine season. n the majority of cases the female
works outward on the twig; but if this is a rule, it is a
very loosely observed one, for many work in the opposite
direction.
Each nest is double; that is, it consists of two chambers
having a common exit, but separated by a thin vertical
partition off wood /Plate 8, i), ;. The eggs are placed
on end in the chambers in two rows, with their head ends
[9_!2]
I'LATE 8
E
C
F
D
Egg punctures and the eggs of the periodical cicada
A, B, C, twigs of dogwood, oak, and apple containing rows of clcada
egg nests. I), cross-section of a twig through an egg nest, showing the
two chambers, each containing a double row of eggs. E, vertical
lengthwise section through two egg nests, showing the rows of slanting
eggs and the fraved lip of the nest opening. F, horizontal section
showing each chamber filled with a double row ofeggs. G, several eggs
(much enlarged)
THE PERIODICAI. CICADA
downward and slanted toward the door. Generally there
are six or seven eggs in each row (E), making twenty-four
to twenty-eight eggs in the whole nest, but frequently
there are more than this. The wood fibers at the en-
trance are much ffaved by the action of the ovipositor
and make a fan-shdped platform in front of the door
(A, B, C). Here the young shed their hatching garments
on emerging from the nest. The series of cuts in the bark
eventuallv run together into a continuous slit, the edges
of which shrink back so that the row of nests cornes to have
the appearance of being ruade in a long groove. This
mutilation kills manv twigs, especially those of oaks and
hickories, the former soon showing the attacks of the
insects bv the dying leaves. The landscape of oak-
covered regions thus becomes spotted ail over with red-
brown patches which often ahnost cover individual trees
from top to bottom. Other trees are not so much in-
jured directly, but the weakened twigs often break in the
wind and then hang down and die.
An ovipositing female Plate 7) finishes each egg nest
in about twentv-five minutes; that is, she digs it out and
fills it with eggs in this length of rime, for each chamber
is tilled as it is excavated. A female about to oviposit
alights on a twig, moves around to the under surface,
and selects a place that suits her. Then, elevating the
abdomen, she turns her ovipositor forward out of its
sheath and directs its tip perpendicularly against the bark.
As the point enters it goes backward, and when in at full
length the shaft slants at an angle of about fortv-five
degrees.
In a number of cases females were frightened awav at
different stages of their work, and an examination o(the
unfinished nests showed that each chamber is filled with
eggs as soon as it is excavated; that is, the insect com-
pletes one chamber first and fills it with eggs, then digs
out the other chamber which in turn receives its quota of
eggs, and the whole job is done. The female now moves
[213 ]
INSECTS
forward a few steps and begins work on another nest,
which is completed in the saine fashion. Some series
consist of only three or four nests, while others contain
as many as twenty and a few even more, but perhaps
eight to twelve are the usual numbers. When the female
bas finished what she deems sufficient on one twig, she
flies away and is said to make further layings elsewhere,
till she has disposed of ber 4co to 6co eggs,, but the writer
ruade no observations covering this point. Probably
the cicada feels it saler hot to intrust all her eggs to one
tree, on the principle of hot putting all your money in the
saine bank.
DEATH OF THE ADULTS
The din of music in the trees continues with monot-
onous regularity into the second week of June, by which
time the mating season is over. Soon thereafter the per-
formers lose their vitality; large numbers of them drop
to the earth where many perish from an internaI fungus
disèase that eats off the terminal rings of the body;
others are mutilated and destroyed by birds, and the
rest perhaps just die a naturaI death. Beneath the trees,
where a great swarm has but recently given such abundant
evidence of lire, the ground is now strewn with the dead
or dying. A large percentage of the living are in various
stages of disfigurement--wings are torn off, abdomens are
broken open or gone entirely, mere fragments crawl about,
stiI1 alive if the head and thorax are intact. In the ma]es
often the great muscle coIumns of" the drums are exposed
and visibly quivering, and many of" the insects, gaine to
the end, even in their diIapidated condition stiII utter
purring remnants of their song.
From now on tiI1 the latter part of JuIy, the onIy evi-
dence of the Iate swarm of noisy visitors wiI1 be the scarred
twigs on the trees and bushes that have received the eggs
and the red-brown patches of dying Ieaves that every-
where disfigure the oaks and hickories.
THE PERIODICAL CICADA
TI-:E BROODS
The two races of the periodical cicada, the seventeen-
year and the thirteen-year, together occupy most of the
eastern part of the United States, except the northern
part of New England, the southeastern corner of Georgia,
and the peninsula of Florida. The western limits extend
into the eastern part of Nebraska, Kansas, Oklahoma,
and Texas. In general, the seventeen-year race is north-
ern, and the thirteen-year race is southern, but, though
the geographic line between the two races is remarkably
distinct, there is considerable overlapping.
While the two cicada races are distinguished from each
other by the length of their lire cycle, the members of each
race do not ail appear in the adult stage in any one year.
Both the seventeen-year race and the thirteen-year race
are broken up into groups of individuals that emerge in
different years, and these groups are known as "broods."
Each brood bas its definite year of emergence, and in
general a pretty well-defined territorv. The territories of
the different broods, however, overlap, or the range of a
small brood may be included in that of a larger one.
Hence, in any particular locality, there is not always an
interval of thirteen or seventeen years between the ap-
pearance of the insects; and it may happen that members
of a thirteen-year brood and of a seventeen-year brood
will emerge in the saine year at the saine place.
The emergence years of the principal cicada broods
bave now been recorded for a long time, and the oldest
record of a swarm is that of the appearance of the "locusts"
in New England two hundred and ninety-five years ago.
A full account of the broods of both races of the periodical
cicada, their distribution, arAd the dates of their emergence,
is given in Dr. C. L. Marlatt's Bulletin, already cited, and
the following abstract is taken from this source:
Wherever a well-defined cicada brood appears in a
certain year, it is generally observed that a few individuals
INSECTS
corne out the year before or the year after. This fact has
suggested the idea that the various broods established at
the present rime had their origin from individuals of a
primary brood that, as we might say, got their dates
mixed, and came out a vear too soon or a year too late,
the multiplying descendants of these individuals thus
founding a new brood dated a year in advance or a year
behind the emergence time of the parent stock. In this
way, it is conceivable, the seventeen-year race might corne
to appear on each of seventeen consecutive years, and the
thirteen-year race on each of thirteen consecutive years.
Individuals emerging on the eighteenth or fourteenth year,
according to the race, would be reckoned as a part of the
first brood of its race.
The facts known concerning the emergence of the
cicadas seem to confirm the above theory, for members of
the seventeen-vear race appear somewhere every year
within the lim'its of their range, and the emergence of
members of the thirteen-year race bas been recorded for at
least eleven out of the possible thirteen years. Ail the
individuals of a brood are hot, of course, descendants of a
single group of ancestors, nor do they necessarily occur
together in a restricted area--they are simply individuals
that coincide in the year of their emergence. However, at
least thirteen of the broods of the seventeen-year race are
well defined groups, for the most part with definitelycircum-
scribed territories, though overlapping in many cases. The
broods of the thirteen-vear race are not so well developed.
The broods are conveniently designated by Roman
numerals. According to the system of brood numbering
proposed by Doctor Marlatt, and now generally adopted,
the brood of the seventeen-year race that appeared last in
1927 is Brood I. This is hot a large brood, but it bas
representatives in Pennsylvania, Maryland, District of
Columbia, Virginia, West Virginia, North Carolina,
Kentucky, Indiana, lllinois, and eastern Kansas. Brood
II, 198, lives in the Middle Atlantic States, with a few
I 261
THE PERIODICAI CICADA
scattering colonies farther west. Brood III, 1929, is
mostlv confined to lowa, Illinois, and ,iissouri. The
largest of the broods is X, covering almost the entire range
of the seventeen-year race. This brood ruade its last
appearance m 1919, and is due next, therefore, in 1936.
The series of broods as numbered thus follows the suc-
cessive years to Brood XVI I, the last brood of the seven-
teen-year race, which will return next in I943.
The small and uncertain broods of the seventeen-year
race are Vil, NII, XV, XVI, and XVII. The cicadas
that emerge in the vears, corresponding with these num-
bers represent incipient broods, being probably the
descendants of a few individuals that sometime became
separated from the larger broods of the vears preceding
or following. One of the smallest of the seventeen-vear
broods is XI, but since its colonies occur in Massahu-
setts, Connecticut, and Rhode lsland, it is likely that it
was more numerous in individuals in former times than
at present. The brood with the oldest recorded history
is XIV. This is a large brood extending over much of
the range of the seventeen-vear race, with colonies in
eastern Massachusetts on Cape Cod and near Plymouth,
the emergence of which was observed bv the early settlers
probably in I634.
The broods of the thirteen-vear race are numbered
flore XVIII to XXX, Brood VIII being that which
appeared last in I9I 9. But there are only two important
broods of this southern race, XIX, which emerged in
I92O , and XXII, which emerged in 924 . In most of the
other years the shorter-lived race is represented by only
a few individuals that emerge here and there over its
range; and none at all are known to appear during the
years corresponding with the numbers XXV and XXVIII.
Trie H..TCHIN¢ Or THE EGGS
Five weeks bave elapsed since the departure of the
cicada swarms. It is nearly six weeks since egg laying
[ :17]
INSECTS
was at its height, and the eggs are now due to hatch almost
anv rime. When studying the cicadas of Brood X near
Washington in I9X9, the writer found the first evidence
of hatching on the twenty-fourth of July. Perhaps the
normal rime of hatching had been delayed somewhat by
heavy tains that fell almost continuously during the ten
days previous, for many eggs examined during this time
were found tobe dead and turning brown, though the
percentage of these was small. The twenty-fifth was hot
and bright ail day. The trees were inspected in the
afternoon. Their twigs had been bare the day belote.
Now, at the entrance holes of the egg nests were little
heaps of shriveled skins, thousands in ail, and each so
light that the merest breath of air suflàced to blow it off;
so, if according to this evidence thousands of nymphs had
hatched and gone, the evidence of as many more must
bave been carried away by the winds. An examination
of many egg nests themselves showed that over half con-
tained nothing but empty shells. Whole series were thus
deserted, and usually ail or nearly ail, of the eggs in any
one series of nests would be either hatched or unhatched.
But often the eggs of one or more nests would be un-
hatched or mostly so in a series containing otherwise only
empty shells. Delay appeared to go by nests rather than
bv individual eggs.
As a very general fuie the eggs nearest the door of an
egg chamber are the ones that hatch first, the others
following in succession, though hot in absolute order.
But unhatched eggs, if present, are always found at the
bottom of the nest, with the tlsual exception of one or two
farther forward. Only occasionally an empty shell occurs
in the middle of an unhatched row. lfthe actual hatching
of the eggs is observed in an opened nest, several nymphs
are usually seen coming out at the saine time, and in
nearly ail cases they are in neighboring eggs, though hot
always contiguous ones. So this rule of hatching, like
most rules, is general but hot binding.
la*8]
THE PER1ODICAI. CICADA
The procedure of the female in placing the eggs leaves
no doubt that the first-laid ones are those at the bottom of
the cell, showing that the order of laying has no relation to
the order of hatching, except that itis mostly the reverse.
I t seems hardly reasonable to suppose that the eggs nearest
the door are affected by greater heat or by a fresher sup-
ply of air, so it is suggested that the order of hatching
may be due simply to the successive release of pressure
along the tightly packed rows, giving the compressed
embryos a chance to squirm and kick enough to split the
inclosing shells. \¥hen hatching once commences it pro-
ceeds very rapidly through the whole nest, showing that
the eggs are ail at the bursting point when the rupture of
the first takes place.
In each lateral compartment of an egg nest the eggs
(Plate 8, E, F) stand in two rows with their lower or
head ends slanted toward the door. (It must be re-
membered that the punctures are ruade on the lower sides
of the twigs, so that the eggs are inverted in their natural
position in the nests.) On hatching, each egg splits ver-
tically over the head and about one-third of the length
along the back, but for only a short distance on the
ventral side. As soon as this rupture occurs, the head
of the young cicada bulges out; and then, by a bending
of the body back and forth, the creature slowly works its
way out of the shell, which, when empty, remains behind
in its original place. The nymphs nearest the door have
an easy exit, but those from the depths of the cell find
themselves still in a confined space between the project-
ing ends of the empty shells ahead of them and the chamber
wall, a passage almost as narrow as the egg itself, through
which the delicate creatures must squirm to freedom.
A newlv-hatched or a newly-born aphid, as we have
seen in Capter VI, is done up in a tight-fitting garment
with neither sleeves nor legs, but nature has been more
considerate in the case of the young cicada, lt, too,
cornes out of the egg clothed in a skin-tight jacket, but
[I91
1NSECTS
g. Free nymph
Fro. I
@
The egg, the newly-hatched nymph shedding the embryonic
skin, and the free nymph of the periodical cicada
2.20]
THE PERIODICAI. CICADA
this garment is hOt a mere bag: it is provided with special
pouches for the appendages or a part of them (Fig.  25, 2).
The incased antennae and the labrum project backward
as three small points lying against the breast. The
front legs are free to the bases of the feinora, though so
tightly held in their narrow sleeves that their joints have
no independent motion. The middle and hind legs are
also incased in long, slim sheaths, but thev alwavs adhere
close to the sides of the bodv. Thus the cicada nymph
newlv-hatched much resembl'es a tiny fish provided onlv
with two sets of ventral fins, but when it gets into actioh
its motions are comparable with the clumsv flopping of a
seal stranded on the beach and trying to get back into
the water (31.
The infant cicada knows it is hot destined to spend its
life in the narrow cavern of its birth, or at least it has no
desire to do so. With its head pointed toward the exit,
it begins at once contortionistic bendings of the body,
which slowlv drive it forward. Bv throwing the head
and thorax lack, the antennal tips and the front legs are
ruade to project so that their points may take hold on
any irregularity in the path. Then a contractile wave
running forward through the abdomen brings up the rear
parts of the bodv as the front parts are again bent back,
and the "flippers" grasp a new point of support. As
these motions are repeated over and over again, the tiny,
awkward thing painfully but surely moves forward, per-
haps helped in its progress bv the inclined tips of the
flexible eggshells pressing against it, on the saine prin-
ciple that a head of barley automatically crawls up the
inside of your sleeve.
Once out of the door no time is lost in discarding the
encumbering garment, but it is never shed in the nest
under normal conditions. If, however, the nest is cut
open and the hatching nymph finds itself in a free, open
space, the embrvonic sheath is cast off immediatelv, often
while the posterior end of the insect's bodv is still in the
[OE21 ]
INSECTS
egg, so that the skin may be left sticking in the open end
of the shell. If the young cicada did hot have to gain its
liberty through that narrow corridor, it might be born
in a smooth bag as are its relations, the aphids.
Watching at the door of an undisturbed nest during a
hatching day, we soon may see a tiny pointed head corne
poking out of the narrow hole. The threshold is soon
crossed, but no more; this traveling in a bag is nota
pleasure trip. A few contortions are always necessary
to rupture the skin, and sometimes several minutes are
consumed in violent twistings and bendings before it
splits. When it does break, a vertical rent is formed
over the top of the head, which latter bulges out until
the cleft becomes a circle that enlarges as the entire head
pushes through, followed rapidly by the bodv (Fig. 125, 47.
The appendages corne out of their sheaths iike tingers out
of a glove, turning the pouches outside in. The antennae
are free first; they pop out and hang stiy downward.
Then the front legs are released and hang stiff and rigid
but quivering with a violent trembling. In a second or
so this has passed, the joints double up and assume the
characteristic attitude, while thev violently claw the air.
Then the other legs and the abdmen corne out and the
embryo is a free young cicada (7). Ail this usuallv
happens in less than a minute, and the new creature i's
alreadv off without so much as a backward glance at
the clthes it has just removed or at the home of its in-
cubation period. Sentiment has no place in the insect
mind.
As the nymphs emerge from the nest, one after an-
other, and shed their skins, the glistening white mem-
branes accumulate in a loose pile belote the entrance,
where they remain until wafted off on the breeze. Each
discarded sheath has a goblet form (Vig. '25, 5, 6), the
upper stiff part remaining open like a bowl, the Iower
part shriveling to a twisted stalk. The antennal and
labral pouches project from the skin as distinct append-
[ 2221
THE PERIODICAL CICADA
ages, but those of the legs are usually inverted during
the shedding and disappear from the outside of the slough,
though the holes where they were pulled in can be round
belote the membrane becomes too dry.
The nymph (Figs. 125, 7; I26) usually runs about at
first in the groove of the twig containing its egg nest and
then goes out on the smooth bark. Here any current
of air is likely to carry it off immediately, but many
wander about for some time, usually going toward the
tips of the twigs, some even getting clear out on the leaves.
But only a few nymphs are ever to be round on twigs
where piles of embryonic skins show that hundreds have
recently hatched; so it is evident that the great majority
either rail off or are blown away very shortly after emerg-
ing. Many undoubtedly fall before the shedding of the
egg membrane, for the inclosed creature has no possible
way of holding on, and even the free nymph has but feeble
clinging powers. Those observed on twigs kept indoors
often fell helplessly from the smooth bark while appar-
ently making rem efforts to retain their grasp. Their
weak claws could get no grip on the hard surface. In-
stead, then, of deliberately launching themselves into
space in response to some mysterious call from below,
the young cicadas simply fall from their birthplace by
mere inability to hold on. But the saine end is gained--
they reach the ground, which is all that matters. Nature
is ever careless of the means, so long as the object is at-
tained. Some acts of unreasoning creatures are assured
by bestowing an instinct, others are forced by with-
holding the means of acting otherwise.
The cicada nymphs are at first attracted by the light.
Those allowed to hatch on a table in a room will leave
the twigs and head straight for the windows ten feet
away. This instinct under natural conditions serres to
entice the young insects toward the outer parts of the
tree, where they have the best chance of a clear drop
to earth; but even so, adverse breezes, irregularity of the
[2231
INSECTS
trees, underbrush, and weeds can hOt but make their
downward journey one of manv a bump and slide from
leaf to leaf before the earth receives them.
The creatures are too small tobe followed with the eye
as they drop, and so their actual course and their be-
havior when the ground is reached are hOt recorded. But
several hatched indoors were placed on loose earth packed
Fro. t .6. The young cicada nymph ready to enter the ground (greatly enlarged)
fiat in a small dish. These at once proceeded to get be-
low the surface. "l'h«v did hot dig in, but simply entered
the first crevice that they met in running about. If the
first happened to terminate abruptly, the nymph came
out again and tried another. In a few minutes all had
round satisfactorv retreats and remained below. The
eagerness with wlich the insects dived into anv opening
that presents itself indicates that the call to enter the
earth is instinctive and imperative ouce their feet have
touched the ground. Note, then, how within a few
minutes their instincts shift to opposites: on hatching,
their first eff,rt is to extricate themselves front the narrow
confines of the egg nest, and it seems unlikely that enough
light can penetrate the depths of this chamber to guide
them to the exit; but once out and divested of their en-
cumbering embrvonic clothes, the insects are irresistiblv
drawu in the diréction of the strongest light, even though
this takes them upward--.ust the opposite of their
[ 2-241
THE PERIODICAI. CICADA
destined course. When this instinct has served its purpose
and has taken the creatures to the port of freest passage
to the earth, all their love of light is lost or swallowed up
in the call to enter some dark creiice narrower eien than
the one so recently left by such physical exertion.
When the young cicadas have entered the earth we
practically have to say good-bye to them until their
return. Yet this recurring event is ever full of interest
to us, for, much as the cicadas bave been studied, it seems
that there is still plenty tobe learned from them each
time they make their visit to our part of the world.
[ 2OE5 ]
CHAPTER VIII
INSECT METAMORPHOSIS
"I'E fascination of mythology and the charm of fairy
raies lie in the power of the characters to change their
form or tobe changed bv others. Zeus would court the
lovely Semele, but knowi]g well she could hot endure the
radiance of a god, he takes the form of a mortal. Omit
the metamorphosis, and what becomes of the myth?
And who would remember the story of Cinderella if the
fairy godmother were left out? The flirtation between
the heroine and the prince, the triumph of beauty, the
chagrin of the haughty sisters--these are bu{ ingredients
in the pot of common fiction. But the transformation
of rats into prancing horses, of lizards into coachman
and lackeys, of rags into fine raiment--this imparts the
thrill that endures a lifetime!
It is hot surprising, then, that the insects, by reason
of the never-ending marvel of their transformations, hold
first place in every course of nature study in our modern
schools, or that nature writers of all times have round a
principal source of inspiration in the "wonders of insect
lire." Nor, finally, should it be ruade a marrer of scorn
if the insects have attached themselves to our emotions,
knowing how ardently the natural human mind craves a
sign of the supernatural. The butterfly, spirit of the
lowly caterpillar, has thus been exalted as a symbol of
human resurrection, and its image, carved on graveyard
gates, still offers hope to those unfortunates interred
behind the walls.
Metamorphosis is a magic word, in spite of its formidable
[26]
INSECT METAMORPHOSIS
appearance; but rendered into English it means simply
"change of form." Not every change of form, however, is
a metamorphosis. The change of a kitten into a cat, of
a child into a grown-up, of a small fish into a large fish
are not examples of metamorphosis, at least not of what
is called metamorphosis. There must be something spec-
tacular or unexpected about the change, as in the trans-
formation of the tadpole into a frog, the change of the
wormlike caterpillar into a moth, or of a maggot into a
FG. IOE 7. Moths of the fall webworm
fly. This arbitrarv limiting of the use of a word that
might, from its derivation, have a much more general
meaning, is a common practice in science, and for this
reason every scientific terre must be defined. Meta-
morphosis, then, as it is used in biology, signifies hot
merely a change of form, but a particular kind or degree
of change; the kind of change, we might say, that would
appear to lie outside the direct line of development from
the egg to the adult.
At once it becomes evident that, by reason of the very
definition we have adopted, our suect is going to be-
corne complicated; for how are we to decide if an observed
change during the growth of an animal is in line or out of
line with direct development? There, indeed, lies a seri-
ous difficulty, and we can only leave it to the biologist to
decide in any particularly doubtful case. But there are
plenty of cases concerning which there is no doubt. A
[ OEOE7 1
INSECTS
caterpillar, for example, certainly is nota form headed
toward a butterflv in its growth, and yet we know itis a
young butterflv, because it hatches out of the butterfly's
egg. And, as the caterpillar grows from a small cater-
pillar to a lar caterpillar, it becomes no more like a
butterfly than it was at first. Itis only after it has
reached maturity as a caterpillar that it undergoes a
process of transformation by which it attains at last the
form of the insect that produced it.
The question now arises as to whether the butterfly is a
form superadded to the caterpillar, or the caterpillar a
form that has deviated from the developmental line of
its ancestors. This question is easily answered: the but-
terfly represents the true adult form of its species, for it
has the essential structure of ail other insects, and it alone
matures the sexual organs and acquires the power of re-
production. The caterpillar is an aberrant form that
somehow has been interpolated between the egg and the
adult of its kind. The real metamorphosis in the lire of
the butterfly, therefore, is not the change of the cater-
pillar into the adult, but the change of the butterfly
embrvo in the egg into a caterpillar. Yet the terre is
usualiy applied to the reverse process by which the
caterpillar is turned back into the normal form of its
specles.
The caterpillar and the butterfly (Fig. 28) furnish the
classical example of insect metamorphosis. Many other
insects, however, undergo the saine kind of transforma-
tion. All the moths as we/l as the butterflies are cater-
pillars when they are young: the famous giant moths
(Plate IO), including the Cecropia, the Promethea, and the
beautiful Luna (Fig. IZ9) , as every nature student knows,
corne from huge fat caterpillars; the humble cutworms
(Fig. I3O) , when their work of destruction is comp/eted,
change into those familiar brown or gray furry moths of
moderate size (A) often round hidden away in the dav-
time and attracted to lights at night. In the spring, tle
PLATE 9
Two species of large moths, natural size, showing the beautifi, l markings
and colors with which even n;ght-flying insects may be adorned.
Upper figure, Heliconisa arpi Schaus, from Brazil; lower, Dirphia
carminata Schaus, from Mexico. (From J. M. Aldrich)
INSECT METAMORPHOSIS
FIG. IOES. The cellery caterpillar, and the butterfly into which it transforms
[ 9 ]
INSECTS
May beetles, or "June bugs" appear (Fig. 3  A) ; they are
the parents of the common white grubs (B) which every
gardener will recognize. The common ladybird beetles
(Fig. 3 a A) are the adults of the ugly larvae (D) that feed
so voraciously on aphids. In the comb of the beehive or
Fro. OE9- The Luna moth
of the wasps' nest, there are many cells that contain small,
legless, wormlike creatures; these are the young bees or
wasps, but you would never know it from their structure,
for they bave scarcely anything in common with their
parents (Fig. 33 A, B). The young mosquito (Fig. I74
I)) we ail know, from seeing it often pictured and de-
scribed and from observing that mosquitoes abound
hercvev thcme wigglers are allowed to lire. The young
[ 3 o I
PLATE 10
Two species of giant moths
Upper figure, the Cecropia moth, female; lower, the Pclyphemus moth,
maie. (From A. H. Clark)
INSECT METAMORPHOSIS
fly is a maggot (Fig. 182 D). The maggots of the house
fly inhabit manure piles; those of the blow flv lire in dead
animals where they feed on the decaying flesh.
We might go on and fill a whole chapter, or a whole book
for that matter, with descriptions of the forms that insects
go through in their metamorphoses, but since other writers
bave demonstrated that this can be done and without ex-
FIIG. 1130. The life of a cutworm
A, the parent moth. B, eggs laid by the moth on a blade of grass. C, a cut-
worm at its characteristic night work, eating off a young garden plant at the
root. D, other cutworms climbing the stalk of plants to feed on the leaves.
E, the cutworm hidden within the earth during the day
hausting the subject, we shall rather turn our attention
here to what may be regarded as the deeper and more ab-
struse phases of insect metamorphosis. Where the facts
themselves are highly interesting, the explanation of them
must be still more so. Eplanations, however, are always
more difficult to present than the facts that are to be ex-
[23]
INSECTS
plained, and if a writer offen does not succeed so well with
the reader in this undertaking, the reader should remember
that his own difficulties of reading are perhaps no greater
than the difficulties of the writer in writing. With a little
extra effort on both sides, then, we may be able to arrive
at a mutual understanding.
In the first place, let us see in what particular manner
the young and the adults of insects differ flore each other.
The adult, of course, is the fully matured tbrm, and it
alone has the organs of reproduction functionally devel-
oped; but this is true of ail animais. The caterpillar and
the moth, the grub and the beetle, the maggot and the fly,
however, differ widely in many other respects, and are so
diverse in appearance and in general structure that their
identities can be known only by observing their transfor-
mations. On the other hand, the young grasshopper
(Fig. 8), the young roach (Fig. 51), or the young aphis
(Fig. 97) is so much like its parents that its family rela-
tionships are apparent on sight. Still, in the case of all
winged insects, there is one persistent difference between
the young and the adult, and this is with respect to the
development of the wings. The wings are always imper-
fect or lacking in the young. The inability to fly puts a
limitation on the activities of the immature insect and
compels.it to seek its living by more ordinary modes of
progression. It may inhabit the land or the water; it may
lire on the surface; it may burrow into the earth or into
the stems or wood of plants--in short, it may lire in a
thousand different places, wherever legs or squirming
movements will take it, but it can hOt invade the air,
except as it may be carried by the wind.
As a first principle in the study of metamorphosis, then,
we must recognize the fact that only the adult insect is
capable oj; flight.
Let us now turn back to the grasshopper (Chapter I);
it furnishes a good example of an insect in which the adults
differ but little from the young, except in the matter of
[ OE3OE]
INSECT METAMORPHOSIS
the wings and the organs of reproduction. As might be
expected, therefore, the young grasshoppers and the
adults live in the saine places and eat the saine kinds of
food in the saine way. This likewise is true of the roaches,
the katydids, the crickets, the aphids, and other related
]3
Fç. 131.  May beetle and its grub
A, the adult beetle which feeds on the leaves of shrubs and trees.
B, the larva, a white grub, which lires in the ground and feeds
on roots
insects. The adults here take no advantage over the
yo.ung in matters of everyday lire by reason of their
WI ngs.
In many other insects, however, the adults bave
adopted new ways of living and particularly of feeding,
ruade possible and advantageous to them because of their
power of flight. Then, in adaptation to their new habits,
they have acquired a special form of the body, of the
mouth parts, or of the alimentary canal. But ail such
modifications, if thrust upon the young, would only be an
impediment to them, because the young are hot capable of
flight. Take the dragonflies as an example. The adult
dragonfly (Fig. 58) feeds on small insects which it catches
in the air, and it can do so because it has a powerful flying
mechanism. The young dragonfly (Figs. 59, 34), how-
ever, could hot follow the feeding habits of its parents; if it
had to inherit the parental form of body and mouth parts
[ OE33 ]
INSECTS
it would be greatly handicapped for living its own lire, and
this would be quite as detrimental to the adult, which
must be developed from the young. Therefore, nature
bas devised a scheme for separating the young from the
adult, by which the latter is allowed to take full advan-
tage of its wings without imposing a hardship or a dis-
ability on its flightless offspring. The device sets aside
the ordinary workings of heredity and makes it possible
for a structural modification to be developed in the adult
and to be suppressed in the young until the time of change
from the last immature stage to that of the adult.
Thus we may state as a second principle of metamor-
phosis that an addt insect ma develop str«tural characters
adaptive to habits that depend'on the power of flight, which
are suppressed in the young, where thev would be detrimental
br. reason of the lack of wings.
When parents, now, assert their independence, what
can we expect of the offspring? Certainly only a similar
declaration of rights. A young insect, once freed from
any obligation to follow in the anatomical footsteps of its
progenitors, so long as it finally reverts to the form of the
latter, soon adopts habits of its own; and then acquires
a form, physical characters, and instincts adapted to such
habits. Thus, the young dragonfly (Fig. 34) bas de-
parted from the path of its ancestors; it bas adopted a lire
in the water, where it feeds upon living creatures which it
pursues by its perfection in the art of swimming and cap-
tures bv a special grasping organ developed from the
under li (B). Lire in the water, too, entails an adaptation
for aquatic respiration. AIl the special acquisitions in
the structure of the young insect, however, must be dis-
carded at the rime of its change to the adult.
A third principle, then, which follows somewhat as a
corollarv from the second, shows us that the young of
insects mav adopt habits advantageous to themselves, and
take on adoptive structt«res that bave no regard to the form of
the adult «md that are discarded at tke fiml transformation.
[ 234]
INSECT METAMORPHOSIS
The degree of departure of the young from the parental
form varies much in different insects. In the cicada, for
example, the nymph is hot essentially different in structure
from the adult except in the matter of the wings, the
organs of reproduction and egg laying, and the musical
Fx6. I3OE. The lire history of a ladybeetle, Adalia biunctata
A, the adult beetle. B, group of eggs on under surface of a leaf. C, a young
larval beetle covered with white wax. D, the full-grown larva. E, the pupa
attached to a leaf by the discarded larval skin
instrument. But the habitats of the two forms are widely
separated, and it is unquestionable that, in the case of the
cicada, it is the nymph that has ruade the innovation in
adopting an underground lire, for with most of the rela-
tives of the cicada the young live practically the saine lire
as the adults.
Animals live for business, hot for pleasure; and all their
instincts and their useful structures are developed for
practical purposes. Therefore, where the young and the
adult of any species differ in form or structure, we may be
sure that each is modified for some particular purpose of
its own. The two principal functions of any animal are
the obtaining of food for its own sustenance, and the
INSECTS
production of offspring. The adult insect is necessarily
the reproductive stage, but in most cases it must support
itself as well; the immature insect bas no other direct
object in lire than that of feeding and of preparing itself
for its transformation into the adult. The feeding func-
tion, however, as we have seen in Chapter IV, involves
FIG. I33. Wasps, or yellow jackets
A, an adult maie of Vespula maculata.
B, C, D, larva, pupa, and adult worker of
l/espula maculiJrons. The worker is a non-
reproductive female and uses ber oviposi-
tor as a sting
most of the activities and structures of the animal, in-
cluding its adaptation to its environment, its modes of
locomotion, its devices for avoiding enemies, its means of
obtaining food. Hence, in studying any young insect, we
must understand that we are dealing almost exclusively
with characters that are adaptive to the feeding function.
When we observe the life of any caterpillar we soon
realize that its principal business is that of eating. The
caterpillar is one creature, at least, that may openly pro-
claire it lires to eat. Whatever else it does, except acts
[ 236 ]
INSECT MEAMORPHOSIS
connected with its transformation, is subservient to the
function of procuring food. Most species feed on plants
and live in the open (Fig. I35 A); but some tunnel into the
leaves (B), into the fruit (D), or into the stem or wood
(Ç). Other species feed on seeds, stored grain, and cereal
preparations. The caterpillars of the clothes moths,
however, feed on animal wool, and a few other caterpillars
are carnivorous.
The whole structure of the caterpillar (Fig. 36) be-
tokens its gluttonous habits, lts short legs (L, tbL) keep
it in close contact with the food material; its long, thick,
wormlike body accommodates an ample food storage and
gives space for a large stomach for digestive purposes; its
hard-walled head supports a pair of strong jaws (Md), and
since the caterpillar has small use for eves or antennae,
these organs are but little developed. Te muscle system
of the caterpillar presents a wonderful exhibition of com-
plexity in anatomical structure, and gives the soft body of
the insect the power of turning and twisting in every con-
ceivable manner. In contrast to the caterpillar, the moth
or the butterflv feeds but little, and its food consists of
liquids, mostly the nectar of flowers, which is rich in
sugars and high in energy-giving properties but contains
little or-none of the tissue-building proteins.
When we examine the young of other insects that
differ markedly from the parent form, we discover the
saine thing about them, namely, the general adaptation of
their body form and of their habits to the function of eat-
ing. Not ail, however, differ as widely from the parent
as does the caterpillar from the moth. The young of
some beetles, for example (Fig. 37), more closely re-
semble the adults except for the lack of wings. Most of
the adult beetles, too, are voracious feeders, and are per-
haps hot outdone in food consumption by the young. But
here another advantage of the double life is demon-
strated, for usually the grub and the adult beetle have
different modes of lire and live in quite different kinds of
[ "-37 ]
INSECTS
places. Each individual of the species, therefore, occupies
at different rimes two distinct environments during its
life and derives advantages from each. It is true that
with some beetles, the young and the adults lire together.
FIG. 134. The nymph of a dragonfly
A, the entire insect, showing the long underlip, or labium (Lb),
closed against the under surface of the head. B, the head and
first segment of the thorax of the nymph, with the labium ready
for action, showing the strong grasping hooks with which the
msect captures living prey
Such cases, however, are only examples of the general rule
that ail things in nature show gradations; but this condi-
tion, instead of upsetting out generalizations, furnishes
the key to evolution, bv which so many riddles may be
solved.
The grub of the bee or the wasp (Fig. 33 B) gives an
excellent example of the extreme specialization in form
that the young of an i*asect may take on. The creature
spends its whole lire in a cell of the comb or the nest where
[ 2381
INSECT METAMORPHOSIS
it is provided with food by the parents. Sorne of the
wasps store paralyzed insects in the cells of the nest for
the young to feed on; the bees give their young a diet of
honey and pollen, with an adrnixture of a secretion from a
pair of glands in their own bodies. The grubs bave noth-
ing to do but to eat; they bave no legs, eyes, or antennae;
each is a rnere body with a rnouth and a stornach. The
adult bees consume rnuch honey, which, like its con-
stituent, nectar, is an energy-forrning food; but they also
eat a considerable quantity of protein-containing pollen.
Yet it is a great advantage to the bees in their social lire
to have their young in the forrn of helpless grubs that
rnust stay in their cells until full-grown, when, by a quick
transformation, they can take on the adult forrn and be-
corne at once responsible rnernbers of the comrnunity. Any
parents distracted bv the incorrigibilities of their offspring
In the adolescent stage can appreciate this.
The young mosquito (Fig. 74 D, E) lires in the water,
where it obtains its food, which consists of minute par-
ticles of organic rnatter. Some species feed at the surface,
others under the surface or at the bottom of the water.
The young rnosquito is legless and its only means of pro-
gression through the water is by a wiggling rnovement
of the sort cvlindrical body. It spends much of its tirne,
however, jut beneath the surface, from which it hangs
suspended bv a tube that projects frorn near the rear end
of the body. The tip of the tube just barely ernerges
above the water surface, where a circlet of small flaps
spread out fiat from its margin serres to keep the creature
afloat. But the tube is prirnarily a respiratory device, for
the two principal trunks of the tracheal systern open at its
end and thus allow the insect to breathe while its body is
submerged.
The adult mosquito (Fig. 174 A), as everybody knows, is
a winged insect, the females of which feed on the blood of
animais and must go after their victims by use o.f their
wings. It is clear, therefore, that it would be quite irn-
[ "-39 ]
INSECTS
possible for a young mosquito, deprived of the power of
flight, no live the lire of its parents and no feed after the
manner of its mother. Hence, the young mosquito bas
adopted its own way of living and of feeding, and this bas
allowed the adult mosquitoes no perfect their specialties
without inflicting a hereditary handicap on their offspring.
Thus agam we see the great advantage which the
species as a whole derives from the double lire of its
individuals.
The flv will only give another example of the saine
thing. "J'he specialized form of the young fly, the maggot
(Fig. 7), which is adapted to the requirements of quite
a different kind of lire from that of the adult fly, relieves
the latter from ail responsibility to its offspring. As a
consequence, the adult fly bas been able to adapt its
structure, during the course of evolution, to a way of
living best suited to its own purposes, unhampered as it
would be if its characters were to be inherited by the
young, to whom thev would become a great impediment,
and probably a fatal" handicap.
A fourth principle of metamorphosis, then, we may say,
is that the species as a whole bas acquired an advmltage by
a double mode of existence, which allows it to take actvantage
of two environmcnts dtering its lifetime, ole suited to the
ftenctions of the young, the other to the fuictions of the
adult.
We noted, in passing, that the young insect is free to
lire its own lire and to develop structures suited to its own
purposes under one proviso, which is that it must even-
tually revert to the form of the adult of its species. At
the period of transformation, the particular characters of
the young must be discarded, and those of the adult must
be developed.
Insects such as the grasshoppers, the katydids, the
roaches, the dragonflies, the aphids, and the cicadas ap-
pear in the adult form when the young sheds its skin for
the last rime. The change that bas produced the adult,
[ 24.0 ]
INSECT METAMORPHOSIS
however, began at an earlier period, and the apparently
new creature was partially or almost entirely formed
within the old skin before the latter was finally shed.
FIG. 135. Various habitats of plant-feeding caterpillars
A, a caterpillar feeding in the open on a leaf. B, leaf miners in an apple leaf,
rhe trumpet miner at a, the serpentine miner at b. C, the corn borer feeding
within a corn stalk. D, the apple worm, or larva of the codling moth, feeding
at the cote of an apple
After the molt, onlv a few last alterations in structure and
some final adiustments are ruade while the wings and legs
of the creature that had been confined in the closelv fitting
skin expand to their full length. The structural "changes
accomplished after the molt, however, varv with different
[24I]
INSETS
species of insects, and with some they involve a consider-
able degree of actual growth and change in the form of
certain parts. The true transformation process, then, is
really a period of rapid reconstructive growth preceding
and following the molt, in which the shedding of the skin
is a mere incident like the raising of the curtain for a new
act in a play. During the intermission the actors bave
changed their costumes, the old scenery has been re-
moved, and the new has been set in place. Thus it is
Th
1 LZ La
_Ab
AbL Sp A.bL
F,G. 136. External structure of a caterpillar
abdomen; .4bL, abdominal legs; H, head; L,, L, La, the thoracic legs; Md,
.jaws; Sp, breathing apertures; Th, thoracic segments
with the insect at the time of its transformation--the
special accouterments of the young have been removed,
and those of the adult have been put on.
The lire of the insect, however, would hot make a good
theatrical production; itis too much of the nature of two
plays given by the saine set of actors. The young insect
is dressed for a performance of its own in a stage setting
appropriate toits act; the adult gives another play and is
costumed accordingly. The actor is the same in each
case only in the continuitv of his individuality. His
rehabi[itation between the two acts wi[l differ in degree
according to the disparity between the parts he plays,
that is, according to how far each impersonation is re-
moved from his natural self.
It is evident, therefore, that the trans.formation changes
of an insect a'ill dif[er in degree, or quantity, according to
[ 4 ]
INSECT METAMORPHOSIS
the sure oJ the departure oJ the young and the departure of
the adult Jrom what would bave been the normal line of devel-
opment if neither had become structurallv adapted to a special
kind oJ lire.
We may express this idea graphically by a diagram
(Fig. 138) , in which the line nm represents what might
have been the straight course of evolution if neither the
adult (I) nor the young (L) had departed along special
lines of their own. But, when the adult and the young
have diverged from some point (a) in their past history,
the line LI, which is the sure of nm to L and of nm to I,
represents the change which the young is bound to make
in reverting to the adult form. The young must, there-
fore, prepare itself for this event in proportion as the
distance LI is short or long.
Where the structural disparity between the young and
the adult is hot great, or is mostly in the external form
of the body, the young insect changes directly into the
adult, as we have seen in the case of the grasshopper
(Fig. 9) and the cicada (Fig. 18). But with manv in-
sects, either because of the degree of difference that has
arisen between the young and the adult, or for some
other reason, the processes of transformation are hot ac-
complished so quickly and require a longer period for their
completion. In such cases, the creature that issues at
the last shedding of the skin bv the young insect is in a
verv unfinished state, and must yet undergo a great
amount of reconstruction before it will attain the form
and structure of the fully adult insect. This happens in
ail the groups of the more highly evolved insects, including
the beetles; the moths and butterflies; the mosquitoes and
files; the wasps, bees, ants; and others. The newly
transformed insect must remain in a helpless condition
without the use of its legs and wings for a period of rime
varying in length with different species, until the adult
organs, particularly the muscles, are completely formed.
In the meantime, however, the sort cuticular layer of
[ Œ43 ]
INSECTS
the skin of the newly emerged insect has hardened,
thus preventing a further growth or change in the cellular
layer of the body wall beneath it. Reorganization can
proceed within the body, but the outer form is fixed and
C
FIG. 137. Adult and larval form of beetles (Order Coleoptera)
A, a ground beetle, Pterosticus. B, the saine beetlë with the right wings spread.
C the larva of Pterosticus. D, an adult beetle, Silpha surinamensis, with the
left wings elevated. E, the larva of the saine species, showing the similarity
in structure to the adult ID) except for the lack of wings and the shormess of
the legs
[ '244
INSECT METAMORPHOSIS
must remain at the stage it had reached when the cuticula
hardened. Only bi a subsequent separation of this
cuticula, allowing another period of growth in the cells of
the body wall, can the form and the external organs of
the adult be perfected. With another molt, therefore,
the fullv formed insect is at last set free, and it now re-
quires only a short time for the expansion of the legs and
wings to their normal size and shape and for the hardening
of the final cuticular layer which will preserve the contours
of the adult.
It thus cornes about that the members qf a large group
of insects haie acquired an extra stage in their lire cycle,
namely, a final reconstructive stage beginning some time
be_[ore the last molt qf the young and completed v«ith a final
added molt a'hich liberates tte fully .formed adult. The
insect in this stage is called a pupa. The entire pupal
stage is divided bi the last molting of the young into a
propupal period, still occupying the loosened cuticula of
the insect in its last adolescent stage, and a true pupal
period, which is that between the shedding of this last
skin of the young and the final molt which discloses the
matured insect.
Ail insects that undergo a metamorphosis may be
divided, therefore, into two classes according as the trans-
formation from the young into the adult is direct or is
COlnpleted in an intervening pupal stage, lnsects of the
first class are said to have ineomplete metamorphosis; those
of the second class, eomplete metamorphosis. The ex-
pressions are convenient, but misleading if taken literally,
for, as we shall see, there are many degrees of "complete"
metamorphosis.
The young of any insect that has a pupal stage in its
lire cycle is called a larva, and the young of an insect
that does not haie a pupal stage is termed a n.vmph, ac-
cording to the modern custom of American entomologists.
But the terre "larva" was formerly applied to the im-
mature stage of ail insects, a usage which should haie
l 45 1
INSECTS
been preserved; and many European entomologists use
the word "nymph" for the stage we call a pupa.
A larva is distinguished from a nymph by the lack of
wing rudiments visible externally, and by the absence of
the compound eyes. Many larvae are blind, but some
of them have a group of simple eyes on each side of the
head substituting for the compound eyes. Nymphs in
general have the compound eyes of the adult insect, and,
as seen an the young grasshopper
L
Fro. x38. Diagram of
metamorphosis
If during tbe course of
tbeir evolution, tbe
adult (I) and the larva
(L)bave independently
diverged from a straigbt
line of development
(nm), the larva must
finally attain the adult
stage by a transforma-
tion (metamorphosis),
tbe degree of wbich is
represented by tbe
length of the line L to I
(Fig. 9), the young dragonfly (Fig. 59),
and the young cicada (Fig.  I4) , the
nymphal wings are small pads that
grow from the thoracic segments after
the first or second molt. The larva,
however, is not actually wingless any
more than is the nymph; its wings are
simply developed internally instead
of externally. When the groups of
cells that are destined to form the
wings begin to multiply, the wing
rudiments push inward instead of
outward, and become small sacs in-
vaginated into the cavity of the body,
in which position they remain through
ail the active lire of the larva. Then,
at the time of the transformation, the
wing sacs are everted, and appear on
the outside of the pupa when the last
larval skin is cast off.
It is difficult to discover any neces-
sary correlation between the exter-
nally wingless condition of the larva
and the existence of a pupal stage in
the lire of the insect; but the two for
some reason go together. Perhaps it
is only a coincidence. To have use-
less organs removed from the surface
INSECT METAMORPHOSIS
is undoubtedly an advantage to a larva, especially to
such species as lire in narrow spaces, or that burrow into
the ground or into the stems and twigs of plants; but
it probably just happened that the pupal stage was first
developed in an insect that had ingrowing wings.
The typical larvae are the caterpillars, the grubs, and
the maggots, young insects with little or no resemblance
to their parents. The larvae of
some ofthe beetles (Fig. 137) and
of some members of the order
Neuroptera, however, are much
like the adults of their species,
except for the lack of external
wings and the compound eyes;
and even among the typical
larvae some species have more of
the adult characters than others.
The caterpillar (Fig. I36) or the
grub of the May-beetle (Fig.
B), for example, both being pro-
vided with legs, have a much
greater resemblance to an adult
insect than has the wormlike leg-
less grub of the wasp (Fig. 133 B)
or the maggot of the fly (Fig. F,c. 139. Springtails, ruera-
I 8 2 D). Hence, we see, the de- bers of the Order Con,bo,
gree of transformation may vary scendedinsects perhapSfrom thedirectlYunknownde-
much even among insects that wingless ancestors of winged
have a so-called "complete" inse«ts
metamorphosis.
There are a few insects that bave no metamorphosis at
ail. These are wingless insects belonging to the groups
known as Collembola and Thvsanura (Figs. 57, 39, 140)
and are probably direct descendants from the primitive
wingless ancestors of the winged insects. These insects
during their growth shed the skin at intervals, but they
do hot undergo a change of form; they illustrate the
[ 247 ]
INSECTS
normal procedure of growth by direct development from
the embryo to the adult.
It must appear that the nymph, or young of an insect
with incomplete metamorphosis, is merely an aberrant
development of the normal form of the young as it
occurs in an insect without metamorphosis. This is
evident from the fact that the nymph has external wings,
fully developed compound eyes, and in general the saine
details of structure in the legs and other parts of the body
as has the adult. Most larvae, on the other hand, have
FJ¢. 4. A bristle-
tail, Thermobia, a mem-
ber of the order Thy-
sanura, another primi-
tive group of wingless
insects. (Twice natu-
rai size)
few or none of the structural details
of the adult that might be expected to
occur in a normal postembryonic ado-
lescent form; but they do bave manv
characters that appear to belong to a
primitive stage of evolution and that
we might expect to find in an em-
bryonic stage of development. The
caterpillar, for example, has legs on
the abdomen (Fig. 36, .tbL), an
embryonic feature possessed by none
of the higher insects in the adult
stage; it has only one claw on its
thoracic legs, a character of crusta-
ceans and myriapods, but hOt of adult
winged insects or of nymphs. Like-
wise, there are certain features of the
internal structure of the caterpi[lar
that are more primitive than in any
adult insect or nymph; and the saine
evidence of primitive or embryonic
characters might be cited of other
larvae. On the other hand, the structura[ details of some
larvae are very much like those of the adults, and such
larvae differ from the adults of their species principally
in the lack of the compound eyes and of external wings.
Now, if ail the insects with complete metamorphosis
[ 48 ]
INSECT METAMORPHOSIS
have been derived from a common ancestor, as seems
almost certain, then the original larvae must have been
ail alike, and thev. must bave had approximately the
structure of those larvae of the present thne that depart
least from the structure of the adult. Therefore itis
evident that many larvae of the present rime bave some-
how acquired certain embrvonic characters. We may
suppose, therefore, either that such larvae have had a
retrogressive evolution into the embryonic stage by
hatching at successively earlier ages, or that certain
embryonic characters representing ancestral characters
but ordinarily quickly passed over in the embryonic
development, have been retained and carried on into the
larval stage. The latter view seems the more probable
when we consider that no larva has a purely embryonic
structure, and that those larvae which have embryonic
features in their anatomy present an incongruous mixture
of embryonic and adult characters.
We may, therefore, finally conclude that the larva of
insects with complete metamorphosis represents the OEvmphal
stage q[ insects with incomplete metamorphosis; and that
the structure of the lar.a bas resulted from a suppression of
the peculiarly adult characters, from an invagination of the
wings, a loss of the compound e.ves, the retention of certain
embrvonic characters, and a special development of the bodv
form"and the organs suited to the particular mode oj r life of
the larva. By allowing for variations in ail these elements
that contribute to the larval make-up, except the two
constants--the invagination of the wings and the loss of
the compound eyes--we may account for ail the variety
in form and structure that the larva presents.
While, in general, the larva remains the saine in struc-
ture from the time it is hatched until it transforms to the
pupa, there are nearly always minor changes observable
that are characteristic of its individual stages. In
Chapter I we encountered the case of the little blister
beetle that goes through severa] verv different forms dur-
[ OE49 ]
INSECTS
ing its development (Figs. I2, 13) , and other examples of
a metamorphosis during the larval lire might be given
from the other groups ofinsects. A larval metamorphosis
of this kind is kr.own as hyperrnetarnorphosis, and it shows
that the larva may be structurally diversified during its
growth to adapt it to several different environments or
ways of obtaining its food.
The reader was given fait warning that the subject of
insect metamorphosis would become difficult to follow,
and even now, with its rea]ization, the writer can hot
assure him that the above analysis is by any means com-
plete or final. Much more might be said for which there
is no space here, and it is hot likely that ail entomologists
will accept ail that bas been said without a discussion,
and possibly some dissension. However, we bave hot
yet reached the end, for we bave so far been dealing only
with the phase of met'amorphosis that has produced the
nymph or the larva, and have only briefly touched upon
the reverse process which reconverts the creature into the
adult.
The pupa unquestionably bas the aspect of an imma-
ture adult. It bas lost all the characteristic features of
the larva, and its organs are those of the adult in the
making. It bas external wing pads, legs, antennae, com-
pound eyes. Its mouth parts are usually in a stage of
development intermediate between those of the larva and
those of the adult. Most of the pupal organs are useless,
since they are neither those of the larva nor entirely those
of the adult, and are hot adapted to any special use the
pupa might make of them, except in a very few cases.
The pupa is, therefore, a helpless creature, unable to
eat, or to make any movement except by motions of the
body. It is usually said to be a "resting" stage, but its
rest is an enforced immobility, and some species attest
their impatience by an almost continuous squirming,
twisting, or wriggling of the movable parts of the body.
It is evident that it must be an advantage to the pupa
[ OE5 o ]
INSECT METAMORPHOSIS
to have some kind of protection, either from the weather,
or from predacious creatures that might destroy it. While
most pupae are protected in one way or another, there are
mme that remain in exposed situations with no kind of
shelter or concealment. The mosquito pupa is one of
these, for it lires in the water along with the larva and
floats just beneath the surface (Fig. 174 F), breathing
by a pair of trumpetlike tubes that project above the
surface from the anterior part of the body. The mos-
quito pupa is a very active creature, and can propel itself
through the water, usually downward, with almost as
much agility as can the larva, and by this means probably
avoids its enemies. The pupa of the common lady-beetle
gives another example of an unprotected pupa (Fig.
I32E). The larvae of these insects transform on the
leaves where they have been feeding, and the pupae re-
main here attached to the leaf, unable to move except by
bending the body up and down. The pupae of mme of
the butterflies also hang naked from the stems or leaves
of plants.
The pupae of many different kinds of insects are to be
found in the ground, beneath stones, under the bark of
trees, or ira tunnels of the leaves, twigs, or wood of plants
where the larvae have spent their lives. Some of these,
especially beetle pupae, are naked, soft-bodied creatures,
depending on their concealment for protection. The
pupae of moths and butterflies, however, are character-
istically smooth, hard-shelled objects with the outlines
of the legs and wings apparently sculptured on the sur-
face (Plate 4 F). Pupae of this kind are called chrysa-
lides (singular, ch,7salis ). Their dense covering is formed
of a gluelike substance, exuded from the skin, that dries
and forms a hard coating over the entire outer surface,
binding the antennae, legs, and wings close to the body.
In addition, the pupae of many moths are inclosed in a
silk cocoon spun by the caterpillar. The caterpillars,
as we shall learn in the next chapter, are provided with
[25l
INSECTS
a pair of silk-producing glands which open through a hol-
Iow spine on the Iower lip beneath the mouth (Fig.
The silk is used bv the caterpillars during the feeding
part of their lives in various ways, but it serves particu-
larlv for the construction of the cocoon. The most
higlly perfected instinct of the caterpillar is that which
impels it t, build the cocoon, often an intricately woven
strt,ctt,re, .just before the rime of its transformation to
the pt,pa. "Fhe caterpillar spins the cocoon around itself,
then sheds its skin, which is thrust into the ear end of
the cocoon as a crt, mpled wad. Plate l  shows the cater-
pillar of a small moth that infests apple trees constructing
its cocoon, finallv inclosing itself within the latter, and
there transformig to the pt,pa.
The larvae of the wasps a,d becs likewise inclose them-
selves within cocoons formed inside the cells of the comb
in which thev have been reared. The cocoon is ruade of
threads, but" the material is sort, and the freshly spun
strands rt, n together into a sheet that dries as a parch-
mentlike lining of the cell. The larvae of many of the
wasplike parasitic insects that feed within the bodies of
other living insects leave their hosts v«hen ready for trans-
formation, and spin cocoons either near the deserted host
or on i ts bodv.
The magg«ts, or larvae, of the flies have adopted an-
other method of acqt,iring protection during the pupal
stage, lnstead of shedding the loosened cuticula previ-
ous to the transformation, the maggot transforms within
the skin, and the latter then shrinks and hardens until
becomes a tough oral capsule inclosing the larva (Fig.
82 E). The capsule is called a p«pari«». It appears,
however, that the larva within the puparitm undergoes an-
other molt before it actt,ally becomes a pupa, for, when the
pupa is formed, it is found to be st,rrounded bv a delicate
mem[)ranous sheath inside the hard wall of the puparium,
and when the adult fly issues it leaves this sheath and a
thin pupal skin behind in the puparial shell.
PLATE 11
The ribbed-cocoon maker (Bucculatrix pom[oliella), a small caterpillar
that inhabits apple leaves
At A the caterpillar is spinning a mat of silk on the surface of a twig.
B shows the silk thread issuing from the spinneret (a) on the under
lip of the caterpillar. At C the caterpillar is erecting a line of silk
palisades around the site of the cocoon. D and E show the cocoon in
the course of construction, built on the silk mat. F is a diagram of
the cocoon on under surface of the support, containing the pupa (g)
and the shed skin of the caterpillar (h). G shows the interior of the
cocoon, its double walls (c, d), and partitions ([) at the front end.
H is the finished cocoon surrounded by the palisades
INSECT M ETA,XlOR PH()$1$
The pllpa has so manv of the characters of the mature
insect that we lnight sa / it is self-evident that itis a part
of the adult stage, except that to sav anything is "se]f-
evident" is almost an unpardonab]e remark in scientific
writing. However, it is clear to the eve that the pupa,
in casting off the skin of the ]arva, has'entirelv discardcd
the larva] for/n, except in certain insects t]at bave a
larva] form in the adult stage. The pupa llliiV rctain a
few Ulfimportant ]arval characters, but ail its principal
organs are th-se of an adult insect in a ha]fwav stage of
development. In studying the cicada, it.was«fi»servcd
that the adult issues from the skin of the nymph in a verv
immature condition. A carefid dissecti«m «f a specime
at this rime would show that the creature is still imperfect
in manv wavs besides those which appear externallv. Bv
verv rapid rowth during the course (,f an hot/r, hoveve,
the adult form and organs are perfected. We have also
noted that with insects of incomplete metam-rphosis the
adult is mostlv formed within the nymphal skin some
rime before thë latter is cast off. The saine thing is true
of a pupa. For several davs bel.re the caterpillar is
readv to molt the last rime, i't remains ahnost motionless
and "its Imdv contracts to perhaps less than hall of the
original lenth. The caterpillar is now said to be in a
"prepupal" stage, but examination of a specimen will
reveal that it bas alread transfcrmed, f-r inside its skin
is a sort pupa in a préliminary stage of development
(l;ig. 4 B).
This first stage of the pupa of a moth or butterflv (Fig.
41 B) is entirely comparable with the immature adult
of the cicada fi»rmed inside the skin of the last stage of
the nymph (Fig. 4  Al. The entire pupal period,
therefore, corresponds with the formative stage of the
cicada, which begins within the nymphal skin and is com-
pleted about an hour after the emergence. The onlv
external différence between the two cases is that the pupa
sheds its skin, making a final added molt belote it becomes
[ 253 ]
INSECTS
a perfect insect, while the immature adult cicada goes
over into the fully mature form quickly and without a
molt.
We may conclude, therefore, that the pupa of insects
with complete metamorphosis corresponds with the immature
stage o the adu]t in insects with incomplete metamorphosis.
This idea concerning the nature of the insect pupa has
FIG. 141. Showing the resemblance of
the pupa of an insect with complete
metamorphosis to the immature adult
form of an insect with incomplete meta-
morphosis
A, immature adult cicada, taken flore the
last nymphal skin. B, immature pupa
of a moth, taken from the last larval
skin. C, the mature pupa of a wasp
[ 254 ]
been well expressed and
more fully substantiated
by E. Poyarkoff, and it
appears to have lnore in
its fayot than the older
view that the pupa cor-
responds with the ]ast
nymphal stage in insects
with incomplete meta-
morphosis. According
to Poyarkoff's theory,
the pupa has no phylo-
genetic significance, that
lS, it does hOt represent
anv ffee-living stage in
the evolution or ances-
tral historv of insects;
it is simply a prolonged
resting period fol]owing
the shedding of the last
larval skin, which termi-
nates with an added
molt when the adult is
fullv formed.
It frequently happens
that a pupa bas some
of the adult characters
better developed than
bas the adult itselL The
pupae of insects that
PLATE 12
The peach-borer moth (Ateeria exitiosa)
Upper figure, the adult male moth (about twice natural slze);
lower figure, the cocoon ruade by the caterpillar from bits of
wood, with the empty shell of the pupa precting from the
opened end
INSECT METAMORPHOSIS
have rudimentary or shortened wings in the adult stage
often have wings larger than those of the adult, indicat-
ing that the wings have been reduced in the adult since
the time when the pupa was first established. Here,
therefore, we see a case of metamorphosis between the
pupa and the adult. Adult moths and butterflies have no
mandibles or have mere rudiments of them (Fig. 63) ,
but the jaws are often quite visible in the pupae (Fig.
 59 H, Md), and the pupa of one moth has long, toothed
mandibles which it uses to liberate itself from the cocoon
before transforming to the adult.
The structural changes that accompany the transfor-
mation of the larva into an adult insect are by no means
confined to the outside of the body. Much internal re-
organization goes on which involves changes in the tissues
themselves. The larva may have built up a highly effi-
cient alimentary canal well adapted for handling its own
particular kind of food, but perhaps the adult has adopted
an entirely different diet. The alimentary canal, there-
fore, must be completely remodeled during the pupal
stage. The nervous system and the tracheal system are
often different in the larval and the adult stages, but the
change in these organs is usually in the nature of a greater
elaboration for the purposes of the adult, though the
larva mav have developed special features that are dis-
carded.
It is in the muscles usually that the most radical re-
constructive processes of the transformation from larva to
adult take place. The muscles of adult insects are at-
tached to the outer cuticular layer of the body wall, which
in hard-bodied insects constitutes the "skeleton," and the
mechanical differences between the larva and the adult
lie in the relation between the muscles and the cuticula.
With the change in the external parts between the two
active stages of the insect, therefore, the larval muscles
are likelv to become entirely unsuited to the purposes of
the adu]t. The special larval muscles, then, must be
[ 55 ]
INSECTS
cleared away, and a new muscle system must be built up
suitable to the adult mechanism. Most of the other
organs are transformed bv a gradual replacement of cells in
their tis,;ues, with the res'uit that each organ itself remains
intact dt,ring the whole period of its alteration--the
insect is never v«ithout a complete alimentary canal, its
b«»dv wall alwavs maintains a contint,ous st,rface. This
conttition, however, is hot entirely true of the muscles,
fi»r with some insects t,ndergoing a high degree of meta-
morphosis i,a exter,aal structure, the muscular system may
st,ffer a complete disorganization, the fibers of the larval
svstem being ira a state of dissolution while those of the
adult are ira the process of development.
The muscles ¢,f adt, lt i,sects, as we have just said, are
attached to the outer
T fS1
FIG. 14o-. Diagram of the attachment of a
muscle to the body walI of an adult insect by
means of the terminal fibrillae (Tf M)
B/, basement membrane; Enrt, endocuticula;
Epct, epicuticula; Epd, epidermis; Exct,
exocuticula; Mol, muscle; Tf M, terminal
fibrillae of the muscle anchored in the cuticula
and the new muscles of thc adt, I
laver of the body wall
I F:ig. r42 ). This layer
is composed partl.v of
a substance called
dz#in formed bv the
cellular laver of the
bodv wall eneath it,
"and constitutes the
cuticuhtr skin that is
shed when the insect
molts. "Fhe newly-
formed ct, ticula is soft
and takes the con-
tour of the celh, lar
laver producing it.
The rot, scies of the
larwt that go over
into the adult stage
t must become fastened
to the new cuticula, and this is possible onlv when the
cutict,la is in the soft formative stage. It has been
pointed out bv Powtrkoff that, for this re«tson, whenever
[ :56 ]
INSECT METAMORPHOSIS
new muscles are formed in an insect a new cuticula must
also be produced in order that the muscle fibers may
become attached to the skeleton. New muscles com-
pleted at the rime of a molt may be anchored into the new
cuticula formed at this time; but if the completion of the
muscle tissue is delayed, the new fibers can become func-
tional only by attaching themselves at the following molt.
Conversely, if the new muscles are not perfected at the
rime of the last normal molt, the insect must have an
extra molt later in order to give the muscles a functional
connection with the body wall.
Thus Poyarkoff would explain the origin of the pupal
stage in the lire cycle of the insect. His theory has much
to commend it, for, as Poyarkoff shows in an analysis of
the various processes accompanying metamorphosis, none
of the cha.nges in any of the organs other than the muscles
would seem to necessitate the production of a new cutic-
ula and thus involve an added molt. If insects with
incomplete metamorphosis add new muscles for the
adult stage, such muscles must be ready-formed at the
time of the last nymphal molt; but it is probable that
there are few such cases in this class of insects.
Adopting Poyarkoff's theory, then, as the most plausi-
ble explanation of why a pupal stage bas become separated
by a molt from the fully-matured adult stage, we may
sav that the reason for the pupa is probably to be found in
the delaved growth of the adult muscles and in the conse-
quent néed of a new cuticula for their attachment.
With a pupal stage once established, however, the pupa
bas undergone an evolution of its own, as bas the larva
and the adult, though to a smaller degree than either
of these two active stages. The pupa is characteristically
different in each of the orders of insects, and many of its
features are clearly adaptations to its own mode of lire.
It is one thing to know the facts and to see the mean-
ing of metamorphosis; it is quite another to understand
how it has come about that an animal undergoes a ruera-
[ OE57 ]
INSECTS
morphic transformation, and yet another to discover how
the change is accomplished in the individual. Meta-
morphosis can be only a special modification of general
developmental growth, and growth toward maturity by
the individual goes over the saine field that the species
traversed in its evolution. Yet, the individual in its
development may depart widely from the path of its
ancestors. It may make many a detour to the right or
the left; it may speed up atone place and loiter along at
another; and, since the individual is rather an army of
cells than a single thing, certain groups of its cells may
forge ahead or go off on a bypath, while others lag behind
or stop for a rest. Only one condition is mandatory, and
this is that the whole armv shall finallv arrive at the saine
point at the saine rime. In each species, the deviations
flore the ancestral path, traveled for manv generations,
bave become themselves fixed and definite trails followed
by ail individuals of the species. The development of
the individual, therefore, mav thus corne to be very
different from the evolutionary historv of its species; and
the lift historv of an insect with complete metamorphosis
is but an extreme example of the complex course that
may result when a species leaves the path of direct de-
velopment to wander in the fields along the way.
The larva and the adult insect bave become in many
cases so divergent in structure, as a result of their separate
departures from the ancestral path, that the embryo bas
become almost a double creature, comprising one set of
cells that develop directlv into the organs of the embryo
and another set held in reserve to build up the adult
organs at the end of the larval lit'e. The characters of
the adult are, of course, impressed upon the germ cells
and lnUSt be carried over to the next generation through
the embryo, but they can not be developed at the saine
rime that the larval organs are functional. Cnse-
quently, the cells, that are to form the special tissues
of the adult remain through the larval period as small
[ -5 8 ]
INSECT METAMORPHOSIS
groups or islands of cells in the larval tissues. These
dormant cell groups are known as imaginal discs, or his-
toblasts. (Imaginal is from imago, an image, referring
to the adult; histoblast means a tissue bud.)
When analvzed closely, the apparent "double" struc-
ture of the embryo will be round to be only the result
of an exaggeration of the usual processes of growth, ac-
companied by an acceleration in certain tissues and a
retardation in others. In general, wherever an adult
organ is represented bv an organ in the larva, even though
the latter is greatly retuced, the cells that are to give this
organ its adult form do hot begin to develop until the
larval growth is completed. But if an organ is lacking
in the larval stage, the regenerative cells mav start to
develop at an earlier period--even in the embryo in a
few cases. Hence, t/te remodeling q[ a larval orgat in the
pupal stage is onlv a comp/etion of that organ's normal de-
velopment, and te production q[ a "ne"' organ is onl
tke deferred development of one tkat kas been suppressed
during tke larval period.
The special organs or forms of organs that the larva
bas built up for its own purposes necessarily become
useless when the larval life has been completed. Such
organs, therefore, must be destroyed if thev can hot be
directlv ruade over into corresponding adult organs.
Their tissues consequently undergo a process of dissolu-
tion, called histolvsis. It can hot be explained at the pres-
ent time what causes histolysis, or why it begins at a
certain time and in particular tissues, but histolysis is
only one of the physiological processes that depend
probably on the action of enzymes. In some insects a
part of the degenerating tissues of the larva is devoured
during the pupal stage by ameboid cells of the blood,
known as p]2agocytes. It was once supposed that the
phagocytes are the active agents of the destruction of the
larval tissues, but this now seems improbable, since histol-
ysis takes place whether phagocytes are present or absent.
[ 59 ]
INSECTS
While the larval tissues are undergoing dissolution,
the adult tissues are being built up from those groups of
dormant cells, the histoblasts, that bave retained their
vitality. Whatever itis that produces histolysis in the
defunct larval tissues, it bas no effect on the regenerative
tissues, which now begin a period of active development,
or histogenesis (i.e., tissue building), which results in the
completion of the adult organs. In most of the organs
the two processes, histolysis and histogenesis, are com-
plemental to each other, the new tissues spreading as the
old are dissolved, so that there is never a lack of con-
tinuitv in the parts undergoing reconstruction. It is only
in the muscles, as we bave already observed, that the
old tissues are destroyed before the new ones are formed.
Because of the high physiological activity (rnembolism)
going on within the pupa, the blood of the insect at this
stage becomes filled with a great quantity of matter
sulting from the dissolution of the larval tissues. During
the pupal period, the insect takes no food nor does it
discharge any waste materials--the substance of the
growing tissues is derived from the débris of those degen-
erating. But the transformation is hOt all direct. The
insect is provided with an organ for converting some of
the products of histolysis into proteid compounds that
can be utilized by the tissues in histogenesis. This organ
is thefa-body (see Chapter IV and Figure 158). During
the larval lire the ceIls of the fat body store up large
quantities of fat, and in some insects glycogen, both of
which energy-forming substances are discharged into the
blood at the beginning of the pupal period. And now
the fat cells become also active agents in the conversion
of histolytic products into proteid bodies, probably by
enzymes gven off from their nuclei. These proteid
bodies are finally also discharged into the blood, where
they are absorbed as nutriment by the tissues of the
newly-formed organs. At the close of the pupal period,
the fat-body itself is often almost entirely consumed or
[ 6o ]
PLATE 13
A
B
C
Il
The red-humped caterpillar (Schizt«ra concinna)
A, the moth in position of repose (natural size). B, moth with wings
spread. C, under surface of apple leaf, showing eggs at ,7, and young
caterpillars feeding at b. D, a caterpillar in next to last stage ofgrowth.
E, full-grown caterpillars (one-half larger than natural size). F, two
cocoons on ground among grass and dead leaves, one cut open showing
caterpillar within before transforming to pupa
INSECT METAMORPHOSIS
is reduced to a few scattered cells, which build up the fat-
body of the adult.
The internal adult organs undergo a continuous develop-
ment throughout the pupal period and are practically
complete when the latter terminates with the molt to the
adult. But the external parts, after quickly attaining a
halfway stage of development at the beginning of the
pupal metamorphosis are checked in their growth by the
hardening of the cuticular covering of the body wall, and
m their half-formed shape they must remain to the end
of the pupal period. It is only by a subsequent growth
of the cellular layer of the body wall beneath the loosened
cuticula of the pupa that the external adult parts are
finally perfected in structure; and it is only when the
pupal cuticula is then cast off and the organs cramped
within it are gien freedom to expand that the adult
insect at last appears in its fully mature form.
[a6 ]
CHAPTER IX
THE CATERPILLAR AND THE aI()TH
"I'HE 1.1FE OF A CATERP1LLAR
la- is one of those bleak davs of early spring that so offen
follow a period of warmth and sunshine, when living things
seem led to believe the fine weather bas corne to stay.
Out in the woods a hand of little caterpillars is clinging
to the surtce of something that appears to be an oral
swelling near the end of a twig on a wild cherrv tree
(Fig. 143). The tinv. creatures, scarce a tenth of an inch
in length, sit motionless, benumbed by the cold, many
with bodies bent into hall circles as if too nearlv ffozen
to straighten out. Probably, however, thev are all un-
conscious and suffering nothing, l'et, if thev were ca-
l»able of it, thev would be wondering what rate brought
them into such a forbidding «orld.
But rate in this case was disguised most likelv in the
warmth of yesterdav, which induced the caterpillars to
leave the eggs in whi'ch thev had safely passed the winter.
The empty eggshells are inside the spindle-shaped thing
that looks so like a swelling of the twig, for in fact this is
merelv a protective covering over a mass of eggs glued
fast to the bark. The surface of the covering is perfor-
ated bv manv little holes from which the caterpillars
emerged, and "is swathed in a network of fine silk threads
which the caterpillars spun over it to give themselves a
surer footing and one thev might cling to unconsciouslv
in the event of adverse weather, such as that which makes
them helpless now. A'hen nature designs anv creature
[ 262]
PL.\TE 14
C
F
The tent caterl3illar ([alacosonm americana)
A, an egg mass on an apple twig (about natural size). B, young
caterpillar feeding on an opening leaf bud. C, branches of an apple
tree with a tent in a (ork, (rom which trails of silk lead outward to
the twigs where the caterpillars are feeding on the leaves. D, a full-
grown caterpillar (three-fourths natural size). E, cocoon. F, 13u13a,
taken l'roIll a cocoon. G, maie moth. H, female moth laying eggs
THE CATERPILI.AR AND THE MOTH
to live under trying circumstances she grants it some
safeguard against destruction.
The web-spinning habit is one which, as we shall see,
these caterpillars will develop to a much greater extent
later in their lives, for our little acquaintances are young
tent caterpillars. They are round most often among
woodland trees, on the chokecherry and the wild black
cherry. But they commonlv infest apple trees in the
orchards, and for this reason {heir species has been named
the apple-tree tent caterpillar, to distinguish it from
related forms.that do hOt com-
monly inhabit cultivated fruit
trees. The scientific naine is
,lla/acosoma americana.
The egg masses of the tent
caterpillar moths are not hard to
find at this season. Thev are
generally placed near the t"lps of
the twigs, which they appear to
surround, and being of the saine
brownish color as the bark, they
look like swollen parts of the
twigs themselves /Plate 4 A,
Fig. 244A). Most of them are
five-eighths to seven-eighths of
an inch in length and ahnost hall
of this in width, but they vary in
thickness with the diameter of
FIG. I43. Young tent cater-
pillars on the egg mass from
which they have just hatched.
(I_- rimes natural size)
the twig. A closer inspection shows that the mass really
clasps the twig, or incloses it like a thick jacket lapped
clear around. In fcrm the masses are usuallv sym-
metrical, tapering at each end, but some are of irregular
shapes, and those that have been placed at a forking or
against a bud have one end enlarged.
The greater part of an egg mass consists of the cover-
ing material, which is a brittle, fihny substance like drv
mucilage. Some of it is often broken away, and some-
[ 263 ]
INSECTS
times the tops of the eggs are entirely bare. The eggs
are placed in a single layer next the bark (Fig. 144 B),
and there are usually 300 or 400 of them. They look like
little, pale-gray porcelain jars packed closely together
and glued to the twig by their rounded and somewhat
compressed lower ends. The tops are fiat or a little
convex. Each egg is the twenty-fourth of an inch in
height, about two-thirds of this in width, and bas a
capacity of one caterpillar. The covering is usually hall
again as deep as the height of the eggs, but varies in thick-
ness in different specimens. The outer surface is smooth
and polished, but the interior is full of irregular, many-
sided ar spaces, separated from one another by rhin
partitions (B).
V'herever the covering of an egg mass bas been broken
away, the bases of the partition walls leave brown lines
that look like cords strapped and tied into an irregular
net over the eggs (B), as if for double security against
insurrection on the part of the inmates. But neither
shells nor fastenings will offer effective resistance to the
little caterpillars when they are taken with the urge for
ffeedom. Each is provided with efficient cutting in-
struments in the form of sharp-toothed jaws that will
enable it to open a round hole through the roof of its cell
(Fig. I44 C). The superstructure is then easily pene-
trated, and the emerging caterpillar finds itself on the
surface of its former prison, along with several hundred
brothers and sisters when all are out.
Ail this time the members of that unfortunate brood
we noted first have been clinging benumbed and motion-
less to the silk network on the covering of their deserted
eggs. The cold continues, the clouds are threatening,
and during the afternoon the hapless creatures are
drenched by hard and chilling tains. Through the night
foliowing they are tossed in a northwest gale, while the
temperature drops below freezing. The next day the
wind continues, and frost cornes again at night. For three
1264 ]
THE CATERPILLAR AND THE MOTH
days the caterpillars endure the hostility of the elements,
without food, without shelter. But already the buds on
the cherry tree are sending out long green points, and
when the temperature moderates on the fourth day and
from which the young caterpillars have emerged. 
D, newly-hatched caterpillars (enlarged about __------
nine times) 1
the sun shines again for a brief
period, the revived outcasts are
able to find a few fresh tips on
which to nibble. In another day
the young leaves are unfolding, of-
fering an abundance of tender for-
age, and the season of adversity
for these infant caterpillars is over.
This family of tent caterpillars was
hatched near Washington on the
25th of March.
The newly-hatched caterpiilars
(Fig. 144 D) are about one-tenth
of an inch in length. The body is
widest through the first segment
[ 265 ]
INSECTS
and tapers somewhat toward the other end. The general
color is blackish, but there is a pale gray collar on the
first segment back of the head and a grayish line along
the sides of the bodv. Most of the segments have pale
rear margins above which are often bright yellow or
orange on the fourth to the seventh segments. There is
usuallv a darker line along the middle of the back. The
bodv s covered with long gray hairs, those on the sides
spre'ading outward, those on the back curving forward.
After a few days of feeding the caterpillars increase to
nearlv twice their length at hatching.
Wlen the weather continues fair after the time of
hatching, the caterpillars begin their lives with happier
days, and their early history is different from that of
those unfortunates described above. Three other broods,
which were round hatching on March _2, before the period
of bad weather had begun, were brought indoors and
reared under more favorable circumstances. These
caterpillars spent but little time on the egg masses and
wasted only a few strands of silk upon them. They were
soon off on exploring expeditions, small processions going
outward on the twigs leading from the eggs or their
vicinity, while some individuals dropped at the ends of
threads to see what might be below. Most, however, at
first went upward, as if they knew the opening leaf buds
should lie in that direction. If this course, though, hap-
pened to lead them up a barren spur, a squirming, furry
mob would collect on the summit, apparently bewildered
bv the trick their instinct had played upon them. On
tle other hand, many followed those that first dropped
down on threads, these in turn adding other strands till
soon a silken stairway was constructed on which indi-
viduals or masses of little woolly bodies dangled and
twisted, as if either enjoying the sport or too fearful to
go farther.
For several davs the young caterpillars led this happy,
irresponsible lire, expl¢ring twigs, feeding wherever an
[ 266 ]
THE CATERPILLAR AND THE MOTH
open leaf bud was encountered, dangling in loose webs,
but spinning threads everywhere. Yet, in each brood,
the individuals kept within reach of one another, and the
trails of silk leading back to the main branch alwavs
insured the possibility of a family reunion whenever tl{is
should be desired.
One morning, the 27th , one family had gathered in its
scattered members and these had already spun a little
tentli.ke web in the
crotch between the ---
main stem of the sup-
\-
porting twig and two
small branches (Fig.
I45). Some members
were crawling on the
surface of the tent,
others were resting
within, still others were
traveling back and
forth on the silk trails 
leading outward on the
branches, and the rest
were massed about
the buds devouring the
young leaves. The es-
tablishment of the tent
marks the beginning of
a change in the cater-
pillars' lives; it entails
responsibilities that de- F,« 45- First t«nt ruade by young t«nt
mand a fixed course of caterpillars. (About halfnatural size)
dailv living. In the lires of the tent caterpillars this
poirt is what the beginning of school days is to us--the
end of irresponsible ffeedom, and the beginning of sub-
jection to conventional routine.
Everv tent caterpillar family that survives infancy
eventually reaches the point where it begins the con-
[ -"6 7 ]
INSECTS
struction of a tent, but the early days are not always spent
alike, even under similar circumstances, nor is the tent
always begun in the saine manner.
In the State of Çonnecticut, where the season for both
plants and insects is much later than in the latitude of
Washington, three broods of tent caterpillars were ob-
served hatching on April 8 of the saine year. These
caterpillars also met with dull and chilly weather that
kept them huddled on their egg coverings for several
days. After four days the temperature moderated suffi-
ciently to allow the caterpillars to move about a lit(le on
the twigs, but none was seen
Fro. 146. Young tent caterpillars matted
on a fiat sheet of web spun in the crotch
between two branches. (About natural
size)
feeding (iii the I4th--six
days af ter the hatching.
Yet they had increased
in slze to about one-
eighth of an inch in
length.
Wherever these cater-
pillars camped in their
wanderings over the small
apple trees they inhabit-
ed, they spun a carpet
of silk to rest upon, and
there the whole family
collected in such a
crowded mass that it
looked like a round, furry
mat (Fig. I46). The car-
pers afforded the cater-
pillars a much saler bed
than the bare, wet bark
of the tree, for if the
sleepers shouid become
stupefied bv cold the claws of their feet would mechanically
hold them fast to the silk during the period of their help-
lessness. The test came on the 16th and the night fol-
lowing, when the campers were soaked by hard, cold rains
[ 268 ]
THE CATERPILLAR AND THE MOTH
till they became so inert they seemed reduced to lifeless
masses of soggy wool. On the afternoon of the 7th the
temperature moderated, the sun came out a few rimes,
the wetness evaporated from the trees, and most of the
caterpillars revived sufficiently to more about a little and
dry their fur. Though a few had been washed off the
carpets by the violence of the storm and had perished
on the ground, and in one camp about twenty dead were
left behind on the web, the majority had survived.
For several days after this, during better weather, the
caterpillars of these families continued their free exist-
ence, feeding at large on the opening buds, but returning
during resting periods to the webs, or constructing new
ones at more convenient places. Often each family split
into several bands, each with its own retreat, yet all re-
mained in communication by means of the silk trails the
members left wherever thev went.
The camping sites were Cther against the surface of a
branch or in the hollow of a crotch. Though the carpet-
like webs stretched over these places were spun appar-
ently only to give secure footing, those at the crotches
often roofed over a space well protected beneath, and fre-
quently many of the caterpillars crawled into these spaces
to avail themselves of their shelter. Yet for twelve days
none of the broods constructed webs designed for cover-
ings. Then, on the morning of the oth, one family was
round to bave spun several sheets of silk above the carpet
on which its members had rested for a week, and all were
now inside their first tent. These caterpillars were near-
ing the end of their first stage, and two days later the
first molted skins were round in the tent, fourteen davs
after the date of hatching.
In Stage II the caterpillars have a new color pattern
and one which begins to suggest that characteristic of the
species in its more mature stages (Fig. 48). On the upper
part of the sides the dark color is broken into a series of
quadrate spots each spot partially split lengthwise by a
[ 69 ]
INSECTS
light streak, and the whole series on each side is bordered
above and below by distinct pale lines, the upper line
often yellowish. Below the lower line there is a dark
hand, and below this another pale line just above the
bases of the legs. The back of the first body segment
bas a brown transverse shield, and the last three segments
are continuously brown, without spots or lines.
From now on the tents increase rapid!y in size by suc-
cessive additions of web spun over the tops and sides,
each new sheet covering a fiat space between itself and the
last. The old roofs thus become successively the floors
of the new stories. The latter, of course, lap over on the
sides, and many continue clear around and beneath the
original structure; but since the tent was started in a
crotch, the principal growth is upward with a continual
expansion at the top. During the building period a
symmetrical tent is really a beautiful object (Plate 4 C).
Hall hidden among the leaves, its silvery whiteness pleas-
ingly contrasts with the green of the foliage; its smooth
silk walls glisten where the sun falls upon them and reflect
warm grays and purples from their shadows.
The caterpillars bave adopted now a community form
of living; ail feed together, ail rest and digest at the saine
time, all work at the saine time, and their days are divided
into definite periods for each of their several duties.
There is, however, no visible system of government or
regulation, but with caterpillars acts are probably func-
tions; that is, the urge probably cornes from some physio-
logical process going on within them, which may be in-
fluenced somewhat by the weather.
The activities of the day begin with breakfast. Early
in the morning the family assembles on the tent roof, and
about six-thirty, proceeds outward in one or several
orderly columns on the branches. The leaves on the
terminal twigs furnish the material for the meal. After
two hours or more of feeding, appetites are appeased, and
[ -7o ]
THE CATERPIII.AR AND THE MOTH
the caterpillars go back to the surface of the tent, usually
by eight-thirty or nine o'clock. Here they do a little spin-
ning on its walls, but no strenuous work is attempted at
FIG. 147. Mature tent caterpillars feeding at night
this rime, and generally within hall an hour the entire
fam]lv is reassembled inside the tent. Most frequently
the crowd collects firs't in the shady side of the outermost
story, but as the morning advances the caterpillars seek
[71 ]
INSECTS
the cooler inner chambers, where they remain hidden
from view.
In the early part of the afternoon a light lunch is taken.
The usual hour is one o'clock, but there is no set time.
Occasionally the participants appear shortly after eleven,
sometimes at noon, and again hot until two or three
o'clock, and rarely as late as four. As they assemble
on the roof of the tent they spin and weave again until
ail are readv to proceed to the feeding grounds. This
meal lasts ai3out an bout. When the caterpillars return
to the tent they do a little more spinning belote they
retire for the afternoon siesta. Luncheon is hot always
fully attended and is more popular with caterpillars in
the .vounger stages, being dispensed with entirely, as we
shall see, in the last stage.
Dinner, in the evening, is the principal meal of the
day, and again there is much variation in the time of
service. Daily observations ruade on rive Connecticut
colonies from the 8th to the 26th of May gave six-thirty
p.m. as the earliest record for the start of the evening
feeding, and nine o'clock as the latest; but the dinner
hour is preceded by a great activity of the prospective
diners assembled on the outsides of the tents. Though
the energy of the tent caterpillars is never excessive, it
appears to reach its highest expression at this time. The
tent roofs are covered with restless throngs, most of the
individuals busilv occupied with the weaving of new web,
working apparently in desperate haste as if a certain task
had been set for them to finish before they should be
allowed to eat. Possibly, though, the stimulus cornes
merely from a congestion of the silk reservoirs in their
bodies, and the spinning of the thread affords relief.
The tent caterpillar does hOt weave its web in regular
loops of thread laid on by a methodical swinging of the
head from side to side, which is the method of most
caterpillars. It bends the entire body to one side, at-
[ OE7 OE ]
THE CATERPILLAR AND THE MOTH
taches the thread as far back as it tan reach, then runs
forward a few paces and repeats the movement, sonletimes
on the saine side, sometimes on the other. The direction
in which the thread is carried, however, is a haphazard
one, depending on the obstruction the spinner meets from
others working in the saine manner. Among the crowd of
weavers there are always a few individuals that are hot
working, though they are just as active as the others.
These are
running
back and
forth over
the surface
of the tent,
like boarders
impatiently
awaiting the
sound of the
dinner bell.
Perhaps
they are in-
dividuals that have finished their
work by exhausting their supply
of silk.
At last the signal for dinner
is sounded. It is heard by the
caterpillars, though it lS hot
audible to an outsider. A
few respond at first and start
off on one of the branches
leading from the tent. Others
follow, and presently a column
is marching outward, usually
keeping to the well-marked
paths of silk till the dis-
tant branches are reached.
Here the line breaks up into
4;; y
I
FIe. 148. Mature tent cater-
pillars. (Naturel size)
[ 273 ]
INSECTS
several sections which spread out over the foliage. The
tent is soon deserted. For one, two, or three hours
the repast continues, the diners often returning home
late at night. Observations indicate that this is the
regular habit of the tent caterpillar in its earlier stages,
and perhaps up to the sixth or last stage of its lire. In
at least nine instances the writer noted entire colonies
back in the tent for the night at hours ranging from
nine to eleven p.m.; but sometimes a part of the crowd
was still feeding when last observed.
In describing the lire of a community of insects it is
seldom possible to make general statements that will
apply to ail the individuals. The best that a writer can
dois to say what he sees most of the insects do, for, as in
other communities, there are always those eccentric mem-
bers who will hot conform with the customs of the major-
ity. Occasionally a solitary tent caterpillar may be seen
feeding between regular mealtimes. Often one works
alone on the tent, spinning and weaving long after its
companions bave quit and gone below for the midday
rest. Such aone appears to be afflicted with an over-
developed sense of responsibility. Then, too, there is
nearly always one among the group in the tent who can
hot get to sleep. He flops this way and that, striking his
companions on either side and keeping them awake also.
These are annoyed, but they. do hot retaliate; they eem
to realize that their restless comrade bas but a common
caterpillar affliction and must be endured.
Many of these little traits make the caterpillars seem
almost human. But, of course, this is just a popular
form of expression; in fact, i t expresses an idea too popular
--we take an over amount of satisfaction in referring to
our faults as particularly human characteristics. What
we really should say is hot how much tent caterpillars
are like us in their shortcomings, but how much we are
still like tent caterpillars. We both revert more or less
in our instincts to times before we lived in communities,
[ 274 ]
THE CATERPILLAR AND THE MOTH
to times when our ancestors lived as individuals irre-
sponsible one to another.
The tent caterpillars ordinarily shed their skins six
times during their lives. At each molt the skin splits
along the middle of the back on the first three body seg-
ments and around the back of the head. It is then
pushed off over the rear end of the body, usually in one
piece, though most other caterpillars cast off the head
covering separate from the skin of the body in all molts
but the last. The moltings take place in the tent, except
the molt of the caterpillar to the pupa, and each molt
renders the caterpillars inactive for the greater part of
two davs. When most of them shed their skins at the
same time there results an abrupt cessation of activity in
the colony. By the rime the caterpillars reach maturity
the discarded skins in a tent outnumber the caterpillars
rive to one.
The first stage of the caterpillars, as already described
(Fig. 144 D), suggests nothing of the color pattern of the
later stages, but in Stage II the spots and stripes of the
mature caterpillars begin to be formed. In succeeding
stages the characters become more and more like those of
the sixth or last stage (Plate 14 D, Fig. I48), when the
colors are most intensified and their pattern best defined.
Particularly striking now are the velvety black head with
the gray collar behind; the black shield of the first seg-
ment split with a medium zone of brown; the white stripe
down the middle of the back; the large black lateral
blotches, each inclosing a spot of silvery bluish white; the
distinctly bluish color between and below the blotches;
and the hump on the eleventh segment, where the median
white line is almost obliterated by the crowding of the
black ffom the sides. Yet the creatures wearing ail this
lavishness of decoration make no ostentatious show, for the
colors are ail nicely subdued beneath the long reddish-
brown hairs that clothe the body. In the last stage, the
average full-grown caterpillar is about two inches long,
[ OE75 ]
INSECTS
but sorne reach a length of two and a half inches when
fully stretched out.
In Connecticut, the tent caterpillars begin to go into
their sixth and last stage about the middle of May. They
now change their habits in many ways, disregarding the
conventionalities and refusing the responsibilities that
bound thern in their earlier stages. They do little if any
spinning on the tent, hOt even keeping it in decent repair.
They stay out ail night to feed (Fig. 147) , unless adverse
weather interferes, thus merging dinner into breakfast in
one long nocturnal repast. This is attested by observa-
tions rnade through rnost of several nights, when the
caterpillars of four colonies which went out at the usual
time in the evenings were round feeding till at least four
o'clock the following mornings, but were always back in
the tents at seven-thirty a.m. When the caterpillars begin
these all-night banquets, they dispense with the mid-
day lunch, their crops being so crammed with food by
morning that the entire day is required for its digestion.
Sonne writers bave described the tent caterpillars as
nocturnal feeders, and sonne have said they feed three
tirnes a day. Both statements, it appears, are correct,
but the observers have hOt noted that the two habits
pertain to different periods of the caterpillars' history.
At any time during the caterpillars' lires adverse
weather conditions may upset their daily routine. For two
weeks during May, days and nights had been fair and
generally warm, but on the ITth the temperature did not
get above 65 ° F., and in the afternoon threatening clouds
covered the sky. In the evening light rains fell, but the
caterpillars of the rive colonies under observation carne out
as usual for dinner and were still feeding when last ob-
served at nine p.m. Rains continued through the night,
however, and the temperature stood almost stationary
between 50 ° and 55 °.
The next morning three of the small trees containing the
colonies were festooned with water-soaked caterpillars, ail
[ OE76 ]
THE CATERPILLAR AND THE MOTH
hanging nnotionless fronn leaves, petioles, and twigs, be-
nunnbed with exposure and incapable of action--nnore
nniserable-looking insects could hOt be innagined. No in-
stinct of protection, apparently, had prevailed over their
appetites; till at last, overconne by wet and cold, they
were saved only by sonne innpulse that led them to grasp
the support so firnnly with the abdonninal feet that they
hung there nnechanicallv when senses and power of nnove-
nnent were gone. Sonne clung by the hindnnost pair of feet
only, others grasped the support with all the abdonninal
feet. One colony and nnost of another were safely housed
in their tents. These had evidently retreated before
helplessness overtook thenn.
By eight o-'clock in the nnorning nnany of the suspended
caterpillars were sufficiently revived to resunne activity.
Sonne fed a little, others crawled feebly toward the tents.
By 9:45 nnost were on their way home, and at IO:4_ç all
were under shelter.
Gentle rains fell during nnost of the day, but the tenn-
perature gradually rose to a nnaxinnunn of 65 °. Only a few
caterpillars fronn the youngest co]onv carne out to feed at
noon. In the evening there was a aard, drenching rain,
after which several caterpillars fronn two of the tents ap-
peared for dinner. The next nnorning, the 9th, the tenn-
perature dropped to 49 °, light rains continued, and nota
caterpillar from anv colony ventured out for breakfast. It
looked as if thev tiad learned their lesson; but it is more
probable they were sinnply too cold and stiff to leave the
tents. In the afternoon the skv cleared, the tennperature
rose, and the colonies resumed their normal life.
The tent caterpillars' mode of feeding is to devour the
leaves clear down to the nnidribs (Figs. 48, I49) , and in
this fashion they denude whole branches of the trees they
inhabit. Since the caterpillars have big appetites, it some-
times happens that a large colony in a small tree or several
colonies in the saine tree may strip the tree bare before
they reach maturity. The writer never saw a colony
[ OE77 ]
INSECTS
reduced to this extremity by its own feeding, but produced
similar conditions for one in a small apple tree by removing
ail the leaves. This was on May 9, and the caterpillars
were mostly in their fifth stage. At seven o'clock in the
evening the cater-
pillars in this col-
ony came out as
usual, and, after
« doing the cus-
tomary spinning
on the tent,
started off to get
their dinner, sus-
pecting nothing
till they came to
the cut-off ends
of the branches.
Then they were
clearly bewildered
.--they returned
and tried the
course over again ;
they tried another
branch, ail the
other branches;
but ail ended
alike in bare
stumps. Yet there
were the accus-
tomed trails, and
their instincts
Fla. 149. Twigs of choke cherry and of apple de- c]ear]y said that
nuded by tent caterpillars silk paths led to
food. So ail night
the caterpillars hunted for the missing leaves; they went
over and over the saine courses, but none ventured be]ow
the upper part of the trunk. By 3:45 in the morning
[
THE CATERPILLAR AND THE MOTH
many had given up and had gone back to the tent, but the
rest continued the hopeless search. At seven-thirtv a few
bold explorers had discovered some remnants ol  water
sprouts at the base of the tree and fed there till ten o'clock.
At eleven ail were back in the tent.
At two o'clock in the afternoon the crowd was out again
and a mass meeting was being held at the base of the tree.
But nobody seemed to have .any idea ofwhat to do, and no
leader rose to the occasion. A few cautious scouts were
making investigations over the ground to the extent of a
foot or a little more from the base of the trunk, but, though
there were small apple trees on three sides rive feet away,
only one small caterpillar ventured off toward one of
these. He, however, missed the mark by twelve inches
and continued onward; but probably chance eventually
rewarded him. At three p.m. the meeting broke up,
and the members went home. They were not seen again
that evening or the next morning.
During this day, the "_ISt, and the next, an occasional
caterpillar came out of the tent but soon returned, and it
was not till the evening of the 22nd that a large number
appeared. These once more explored the naked branches
and traveled up and down the new paths on the trunk, but
none was observed to leave the tree. On the -3rd and
24th no caterpillars were seen. On the 2çth the tent was
opened and onlv two small individuals were round wlthin
it. Each of th'ese was weak and flabby, its alimentary
canal completely empty. But what had become of the
rest? Probablv they had wandered off unobserved one
bv one. Certé, inlv there had been no organized migra-
tion. Solitary caterpillars were subsequently found on a
dozen or more small apple trees in the immediate vicinity.
It is likelv that most of these had molted and had gone
into the lst stage, since their time was ripe, but this was
not determined.
After the caterpillars go over into their last stage, the
tents are neglected and rapidly fall into a state of dilapida-
[ 279 ]
1 NS ECTS
tion. Birds often poke holes in them with their bills and
rip off sheets of silk which they carry away for nest-build-
,ng purposes. The caterpillars do not even repair these
damages. The rooms of the tent become filled with ac-
cumulations of frass, molted skins, and the shriveled
bodies of dead caterpillars. The walls are discolored by
tains which beat into the openings and soak through the
refise. Thus, what were shapely objects ofglistening silk
are transmuted into formless masses of dirty rags.
But the caterpillars, now in their finest dress, are ob-
livious of their sordid surroundings and sleep ail dav.
anaidst these disgusting and apparently insanitary condi-
tions. However, the life in the tents will soon be over;
so it appears the caterpillars simply think, "What's the
use?" But of course caterpillars do hot think; thev arrive
at results bv instinct, in this case bv the lack of an i'nstinct,
for thev hve no impulse to keep the tents elean or in
Fro. o. A tent caterpillar in the last
stage of its growth, leaving the tree con-
taining its nest by jumping from the end
of a twig to the ground
repair when doing so
would be energy wasted.
Nature demands a prac-
tical reason for most
things.
The tent lire continues
about a week after the
last molt, and then the
familv begins to break
up, t[ae members leaving
singly or in bands, but al-
wavs as individuals with-
Otl[ further COllcerll for
one another. Judging
from their previous me-
thodical habits, one ould suppose that the caterpillars
starting off on their journeys would simply go down the
trunks of the trees and walk away. But no; once in their
life they must have a dramatic moment. A caterpillar
cornes rushing out of a tent as if suddenly awakened from
[ 8o ]
THE CATERPILI.AR AND THE MOTH
some terrible dream or as if pursued by a demon, hurries
outward along a branch, goes to the end of a spur or the
tip of a leaf, and without slackening continues into space
till the end of the support tickles his stomach, when sud-
denly he gives a flip into the air, turns a somersault, and
lands on the ground (Fig. 15o).
The first performance of this sort was observed on
May 15 in the Connecticut colonies. On the afternoon
of the 19th, twentv or more caterpillars from two neigh-
boring colonies were seen leaving the trees in the saine
fashion within half an hour. Most of the members of one
of these colonies had their last molt on Mav I2 and 13 .
During the next few davs other caterpillrs were ob-
served jumping from four trees containing colonies under
observation. Ail of these went off individuallv at various
times, but most of them early in the afternc;on. Many
caterpillars simply drop off" when they reach the end of
the branch, without the acrobatic touch, but only three
were seen to go down the trunk of a tree in commonplace
style.
The population of the tents gradually decreases during
several davs following the time when the first caterpillar
departs. ne of the two tents from which the general
exodus was noted on Mav 19 was opened on the 2lSt and
was fimnd to contain onl'.v one remaining caterpillar. On
the evening of the 22nd a solitary individual was out feed-
ing from the other tent. The two younger colonies main-
tained their numbers until the 22nd, after which they
diminished till, within a few days, their tents also were
deserted. The members of ail these colonies hatched
from the eggs on April 8, 9, and Io, so seven weeks is the
greatest length of time that anv of them spent on the trees
of their birth. The caterpillar that left the tent on the
çth came flore a colonv that began to hatch on April 1%
gving an observed minimum of thirty-six days.
After the mature caterpillars leave the tents, they
wander at large and feed wherever they find suitable
INSECTS
provender, enjoying for a while a new lire free from the
domestic routine that bas bound them since the days of
their infancy. But even their liberty has an ulterior pur-
pose: the time is now approaching when their lives as
caterpillars must end and the creatures must go through
the mysteries of transformation, which, if successfullv
accomplished, will convert them into winged moths. I't
would clearly be most unwise for the caterpillars of a
colony to undergo the period of their metamorphosis
huddled in the remains of the tent, where some untoward
event might bring destruction to them ail. Nature has,
therefore, implanted in the tent caterpillar a migratory
t,rge, which now becomes active and leads the members of
'I;. çI. The cocoon of atent cater-
pillar. (Natural size)
a familv to scatter far and
wide. About a week is
allowed for the dispersal,
and then, as each wan-
derer feels within the
first warnings of ap-
proaching dissolution, it
selects a suitable place
for inclosing itself in a
COCO011.
I t is diflàcult to find many cocoons in the neighborhood
where large numbers of caterpillars have dispersed, but
such as may be recovered will be round among blades of
grass, under ledges of (ences, or in sheds and barns where
thev are hot disturbed. The cocoon is a slender oval or
a]most spindle-shaped object, the larger ones being about
an inch long and hall an inch in width at the middle
I Plate 4 E Fig. l çl). The structureis spun ofwhit¢ silk
thread, but its waÏls are stiffened and colored by a yellow-
ish substance infiltrated like starch through the meshes
of the fabric.
In building the cocoon the caterpillar first spins a loose
network of threads at the place selected, and then, using
this for a support, weaves about itself the walls of the final
[ _8]
THE CATERPILI.AR AND THE MOTH
structure. On account of its large size, as compared with
the size of the cocoon, the caterpillar is forced to double
on itself to fit its self-imposed cell. Most ofits hairs, how-
ever, are brushed off and become interlaced with the
threads to forma part of the cocoon fabric. When the
spinning is finished, the caterpillar ejects a yellowish,
pasty liquid from its intestine, which it smears ail over the
mner surface of the case; but the substance spreads
through the meshes of the silk, where it quickly dries and
gives the starchv stiffness to the walls of the finished
cocoon. It readi'ly crumbles into a yellow powder, which
becomes dusted over the caterpillar within and ftoats off in
a small yellow cloud whenever a cocoon is pulled loose
from its attachments.
The cocoon is the last resting place of the caterpillar. If
the insect lires, it will corne out of its prison as a moth,
leaving the garments of the worm behind. It may, how-
ever, be attacked by parasites that will shortly bring about
its destruction. But even if it goes through the period of
change successfullv it nmst remain in the cocoon about
three weeks. In the meantime it will be ofinterest to learn
something of the structure of a caterpillar, the better to
understand some of the details of the process of its trans-
formation.
THE STRUCTURE AND PHYSIOLOG" OF THE CATERPILLAR
A caterpillar is a young moth that bas carried the idea
of the independence of youth to an extreme degree, but
which, instead of rising superior toits parents, bas de-
generated into the form of a worm. An excellent theme
this would furnish to those who at present are bewailing
what they believe to be a shocking tendency toward an
excess of independence on the part of the young of the
human species; but the moral aspect of the lesson some-
what loses its force when we learn that this freedom of the
caterpillar from parental restraint gives advantages to
both young and adults and therefore results in good to
[ -83 ]
INSECTS
the species as a whole. Independence entails responsibil-
ities. A creature that leaves the beaten paths of its an-
cestors must learn to take care ofitse]fin a new way. And
Flc. 15OE. The head of a tent caterpillar
A, facial view. B, under surface. C, side view. .dnt, antenna; Clp, clypeus;
For, opening of back of head into body; ttphy, hypopharynx; Lk, labium; Lin,
labrum; 3Id, mandible; Mx, maxilla; O, eyes; Spt, spinneret
this the caterpillar has learned to do preeminently well,
as it bas corne up the long road of evolution, till now it
possesses both instincts and physical organs that make it
F¢. x$3. The mandibles, or
biting jaws, of the tent cater-
pillar detached from the head
A, front view of right mandi-
ble. B, under side of the left
mandible, a and p, the an-
terior socket and posterior
knob by which the jaw is
hinged to the head; EAcl,
RMd, abductor and adductor
muscles that more the jaw in
a transverse plane
one of the dominant forms of in-
sect lire.
The external organs of princi-
pal interest in the caterpillar are
those of the head (Fig. 152).
These include the eyes, the an-
tennae, the mouth, the jaws, and
the silk-spinning instrument. A
facial view of a caterpillar's head
shows two large, hemispherical
lateral areas separated by a medi-
an suture above and a triangular
plate (C/p) below. The walls of
the lateral hemispheres give at-
tachment to the muscles that
move the jaws, and their size is
no index of the brain-power of
[ -84 ]
THE CATERPILLAR AND THE MOTH
the caterpillar, since the insect's brain occupies but a small
part of the interior of the head (Fig. 154 , Br). From the
lower edge of the triangular facial plate (Fig. ISZ, Clp) is
suspended the broad, notched front lip, or labrum (Lin)
that hangs as a protective flap over the bases of the jaws.
At the sides of the labrum are the very small antennae
(.4rit) of the caterpillar. On the lower part of each lateral
hemisphere of the head are six small simple eyes, or
ocelli (O), rive in an upper group, and one near the base of
the antenna. With all its eyes, however, the caterpillar
Cr Vent Ht /val int
Br..Rect
Phy -'"'- -  _
Mth / ,   
oeGn kG1
Fro. 54- Diagrammatic lengthwise section of a caterpillar, showing the
principal internal organs, except the tracheal system
d, anus; r, brain; C, crop; I, heart; II, ;ntestine; 11, Malpighian tubule
(two others are cut off near their bases); I, mouth; Oe, oesophagus;
pharynx; R«et, rectum; çl, silk gland; o«çn, suboesophageal ganglion;
stomach, or ventriculus;  ventral nerve cord
appears to be very nearsighted and gives little evidence of
being able to distinguish more than the presence or ab-
sence of an object before it, or the difference between light
and darkness. Those tent caterpillars that were starving
on the denuded tree failed to perceive other food trees in
full leaf only a few feet away.
The general external form and structure of the tent
caterpillar is shown at A of Figure 159. The body is soft
and cylindrical. The head is a small, hard-walled capsule
attached to the body by a short flexible neck. Back of
the head and neck cornes first a body region consisting
of three segments that bear each a pair of small, jointed
legs (L); and then cornes a long region composed of ten
segments supported on rive pairs of short, unjointed legs
[ 85 ]
INSECTS
(.4L), the first four pairs being on the third, fourth, fifth
and sixth segments, and the last on the tenth segment.
The region of the three segrnents in the caterpillar bear-
ing the jointed legs corresponds with the thorax of an
adult insect (Fig. 63, Th), and that following corresponds
with the abdomen (db). The thorax of the adult insect
constitutes the locornotor center of the body, but the
worrnlike caterpillar has no special locornotor region, and
hence its body is hot separated into thorax and abdomen.
The thoracic legs of the caterpillar terrninate each in a
single claw, but the foot of each of the abdorninal legs
has a broad sole provided with a series or circlet of claws
and with a central vacuum cup. The abdorninal legs
of the caterpillar, therefore, are important organs of pro-
gression, and are the chier organs of grasping or of cling-
ing to hard or fiat surfaces.
The jaws of the caterpillar consist of a pair of large,
strong rnandibles (Fig. 152 , 3fd) concealed, when closed,
behind the labrurn. Each jaw is hinged to the lower
edge of the cranium at the side of the rnouth by two ball-
and-socket hinges in such a rnanner that, when in action,
it swings outward and inward on a lengthwise axis. The
cutting edges are provided with a number of strong teeth
(Fig. 53), the points of which corne together or slide
past each other when the jaws are closed.
The large complex organ that projects behind or below
the rnouth like a thick under lip (Fig. 5 OE C) is a com-
bination of three parts that are separate in other insects.
These are the second pair of soif jaw appendages, called
maxillae (B, C, Mx), and the true under lip, or labium
(Lb). The rnost important part of this cornposite struc-
ture in the caterpillar, however, is a hollow spine (A,
B, C, Spt) pointed downward and backward frorn the
end of the labiurn. This is the spinneret. Frorn it issues
the silk thread with which the caterpillar weaves its tent
and its cocoon.
[ OE86 ]
THE CATERPILI.AR AND THE MOTH
The fresh silk is a liquid formed in two long, tubular
glands extending far back from the head into the bodv of
the caterpillar (Fig. 154 , 8kGl). The middle part of each
tube is enlarged to serve as a reservoir where the silk
liquid may accumulate (Fig. 55 A, Res); the anterior
narrowed part constitutes the duct (Da), and the ducts
FIG. I. The silk glands and spinning organs of the tent caterpillar
A, the silk-forming organs, consisting of a pair of tubular glands (GI, GI), each
enlarging into a reservoir (Res), and opening through a long duct (Dct) into
the silk press (Pr), with a pair of accessory glands (glands of Filippi, GIF) opening
into the ducts
B, side view of the hypopharynx (Hphy) with terminal parts of right maxilla
(Mx) and labium (Lb) attached, showing the silk press (Pr), its muscles, and
the ducts (Dot) opening into it, and the spinneret (,çpt) through which the silk is
discharged from the press
C, upper view of the silk press (Pr), showing the four sets of muscles (Mcls)
inserted on its walls and on the rod-like raphe (Rph) in its roof
D, side view of the silk press, spinneret, raphe, and muscles
E, cross-section of the silk press, showing its cavity, or lumen (Lum), which is
expanded by the contraction of the muscles
[ 87 ]
INSECTS
from the two glands unite in a median thick-walled sac
known as the silk press (Pr), which opens to the exterior
through the spinneret. Two small accessory glands, which
look like bunches of grapes and which are sometimes
called the glands of Filippi (Fig. 55 A, B, C, G/F), open
into the silk ducts near their front ends.
The relation of the silk ducts and the silk press to the
spinneret is seen in the side view of the terminal parts of
the labium and the left maxilla, given at B of Figure 55-
The silk press (Pr) is apparently an organ for regulating
the flow of the liquid silk material into the spinneret. It
Flç. 156. The alimentary
canal of the tent cater-
pillar
A, belote feeding. B, after
feeding. Cr, crop; Int, in-
testine; Mal, Malpighian
tubules; OE, oesophagus;
Rect, rectum; lent, ventri-
culus
has been supposed, too, that it
gives form and thickness to the
thread, but the liquid material has
still to pass through the rigid tube
of the spinneret.
The cut end of the press, given at
E of Figure 55, shows the crescent
form of the cavitv (Lum) in cross-
section, and the thickening in its
roof (Rph), called the raphe. Mus-
cles (Mcls) inserted on the raphe
and on the sides of the press serve
to enlarge the cavity of the press
by lifting the infolded roof. The
four sets of these muscles in the
tent caterpillar are shown at Ç.
The dilation of the press sucks the
liquid silk into the cavitv through
the ducts from the reservoirs, and
when the muscles relax, the elastic
roof springs back and exerts a
pressure on the silk material, which
forces the latter through the tube
of the spinneret. The continuous
passageway from the ducts through
[ 88 ]
THE CATERPILLAR AND THE MOTH
the press and into the spinneret is seen from the side
at D.
The silk liquid is gummy and adheres tightl.v to what-
ever it touches, while at the saine time it hardens rapidl.v
and becomes a tough, inelastic thread as it is drawn out
of the spinneret when the caterpillar swings its head away
from the point of attachment.
The mouth of the caterpillar lies between the jaws and
the lips. It opens into a short gullet, or oesophaXus, which,
with the pharynx, constitutes the first part of the alimen-
tarv canal (Fig. 154 ' Pli.v, Oe). The rest of the canal is a
wic{e tube occup.ving most of the space within the cater-
pillar's bodv and is divided into the trop (Cr), the stomach,
or ventricul'us (l'ent), and the ilttestMe (lt). The crop is
a sac for receiving the food and varies in size according
to the amount of food it contains (Fig. 56 A, B, Cri.
The stomach (Peu) is the largest part of the canal. I ts
walls are loose and wrinkled when it is empty, or smooth
and tense when it is full. The in-
testine (Int) consists of three divi-
sions, a short part just back of the
stomach, a larger middle part, and a
saclike end part called the rectum
(Rect). Six long tubes (Mal) are
wrapped in manv colis about the in-
testine and run iorward and back in
long loops over the rear hall of the
stomach. The three on each side
unite into a short basal tube, which
opens into the first part of the intes-
tine. The terminal partsofthe tubes
are coiled inside the muscular coat
Fro.  57- Crystals
from the Malpighian
tubules of the tent
caterpillar, which are
ejected into the walls
of the cocoon
of the rectum. These tubes are the Malpighian tubules.
When a tent caterpillar goes out to feed, the fore part
of its body is sort and flabbv; when it returns to the tent
the saine part is tight and firm. This is because the tent
caterpillar carries its dinner home in its crop, digests it
[ =89 ]
INSECTS
slowlv while in the tent, and then goes out for more when
the crop is empty. It is quite easy to tell by feeling one
of these caterpillars whether itis hungry or hot. The
empty, contracted crop is a small bag contained in the
first three segments of the body (Fig. 56 A, Cr); but the
full crop stretches out to a long cylinder like a sausage,
filling the first six segments of the body fB, Cr), its rear
end sunken into the stomach, and its front end pressed
against the back of the head.
The fresh food in the crop consists of a sort, pulpy mass
of leaf ffagments. As this is passed into the stomach,
the crop contracts and the stomach expands, and the
caterpillar's center of gravity is shifted backward with the
food burden. As the stomach becomes empty there ac-
cunulates in it a dark-brown liquid, and it becomes in-
flated with bubbles of gas. When the caterpillar goes to
its meals both crop and stomach are sometimes empty,
but usua]]v the stomach still contains some food besides
an abundance of the brown liquid and numerous gas
bubbles. The refuse that accumulates in the middle sec-
tion of the intestine is subjected to pressure bv the mus-
cles of the intestinal wall, and is here molded into a pellet
which retains the imprint of the constrictions and pouches
of this part of the intestine and looks like a small mulberrv
when passed on into the rectum and fina!lv extruded from
the body.
The alimentarv canal is a tube ruade of a single layer
of cells extending through the bodv; but its outer surface,
that toward the body cavity, is covered by a muscle layer
of lengthwise and crosswise fibers, which cause the more-
ment of the food through the canal. The gullet and crop
and the intestine are lined internally with a thin cuticula
continuous with that covering the surface of the body,
and these linings are shed with the bodv cuticula every
rime the caterpillar molts.
The Malpighian tubules (Figs. 54, 56 A, Mal), being
the kidneys of insects, are excretory organs that remove
[ 9 o ]
THE CATERPII.IAR AND THE MOTH
from the blood the waste products containing nitrogen,
and discharge them into the intestine along with the waste
parts of the food from the stomach. Ordinarilv the iXlal-
pighian tubules are of a whitish color, but just'before the
tent caterpillar is readv to spin its cocoon thev become
congested with a brig[at vellow substance, l.;nder th'e
mcroscope this is seen to consist of masses of square,
oblong, and rod-shaped crvstals (Fig. 57)- At this rime
the caterpillar has ceased to feed and the alimentary canal
contains no food or food refuse. The intestine, however,
FIG. ! ç8. A piece of the fat-body of the rail weborm
a, a, globules of fatty oil in the cells; J)«, N«, nuclei of the cells
becomes filled with the vellow mass from the Malpighian
tubules; and this is the material with which the tent
caterpillar plasters the walls of its cocoon, giving them
their yellowish color and stiffened texture. The vellow
powder of the cocoon, therefore, consists of the cvstals
from the Malpighian tubules.
We now corne to the question of why the caterpillar eats
so much. It is ahnost equivalent to asking, "\Vhy is a
caterpillar?" The caterpillar is the principal feeding
stage in the insect's lire; eating is its business, its reason
for being a caterpillar. It eats hot onlv to build up its
own organs, manv of which are to be broken down to
furnish building aterial for those of the moth, but it
eats also to store up within its body certain materials in
excess of its own needs, which likewise will contribute to
the growth of the moth.
[9  ]
INSECTS
The most abundant of the food reserves stored by the
caterpillar is fat. With insects, however, fat does hot
accumulate among the muscles and beneath the skin.
sects do hot become "fat" in external appearance. Their
fatty products are held in a special organ called thefat-
bodv.
The fat tissue of a caterpillar consists of many small,
fiat, irregular masses of fat-containing cells scattered ail
through the body cavity, some of the masses adhering in
chains and sheets forming a loose open network about the
alimentary canal, others being distributed against the
muscle layers and between the muscles and the body wall.
The cells composing the tissue vary much in size and
shape, but they are always closely adherent, and in fresh
material itis often difficult to distinguish the cell bound-
aries. Specimens prepared and stained for microscopic
examination, however, show distinctly the cellular struc-
ture (Fig. I58). Each cell contains a darkly-stained
nucleus (Nu), but the nuclei are seen only where they lie
in the plane of the section. The protoplasmic area about
the nucleus in each cell appears to be occupied mostly
with hollow cavities of various sizes (a), but in life each
cavity contains a small globule of fatty oil. The proto-
plasmic material between the oil globules contains also
glycogen, or animal starch, as can be shown by staining
with iodine. Both fat and glycogen are energy-forming
compounds, and their presence in the fat cells of the
caterpillar shows that the fat-body serves as a storage
organ for these materials during the larval life. The stored
fat and glycogen will be consumed during the period of
metamorphosis, when the insect is deprived of the power
of feeding and receives no further nourishment from the
alimentary canal. The transformation processes will then
depend upon the food materials that the caterpillar has
stored in its own body; and the success of the pupal meta-
morphosis will depend in large measure on the quantity
of these food reserves. A starved caterpillar, therefore,
[ 9  ]
THE CATERPILLAR AND THE MOTH
is likely to be unable to accomplish its transformation, or
it will produce a dwarfed or an imperfect adult.
How THE CATERPILLAR BECOMES A IOTH
A short rime before the caterpillar is ready to spin its
cocoon, it ceases feeding. Its body, as we have just
learned, contains now an abundance of energy-giving sub-
stances stored in the cells of its fat tissue. When the work
of constructing the cocoon is started, the alimentary canal
is devoid of food material, the crop is contracted to a
narrow cylinder, and the stomach is shrunken and flabby.
The stomach, however, contains a mass of sort, orange-
brown substance which, when examined under the micro-
scope, is round to consist, hot of plant tissue, but of animal
cdls; it is, in fact, the cellular lining of the caterpillar's
stomach which bas already been cast off into the cavity
of the stomach. The latter is now provided with a new
cell wall. The shedding of the old stomach wall marks the
first stage in the dismantling of the caterpillar; it is the
beginning of the pupal metamorphosis which will convert
the caterpillar into the moth. The new stomach wall will
first digest and absorb the débris of the old, in order to
conserve its proteid materials for the constructive work
of the pupa, and it will then itself become transformed
into the stomach of the moth.
After the caterpillar bas shut itself into the cocoon, its
life as a caterpillar is almost ended. Its external appear-
ance is alreadv much altered by the contraction of the
bodv and the "loss of the hairv covering, and during the
next three or four days a furter characteristic change of
form takes place. As the bodv continues to shorten, the
first three segments become crowded together; but the
abdomen swells out, while the abdominal legs are re-
tracted until thev all but disappear. The creature is now
(Fig. I59 B) onl." half the length of the active caterpillar
(A), and it would scarcely be recognized as the saine in-
dividual that so recently spun itself into the cocoon.
l "-93 ]
INSECTS
During the progress of change in the external form, the
caterpillar gradually loses the power of movement. The
resultant inactive period in an insect's lire, immediately
preceding the visible change to the pupa, is called the
A."  .g=
Fie,. x9. Transformation of the tent caterpHar into the moth
[ :94 ]
THE CATERPILLAR AND THE MOTH
prepupal stage of the larva. The insect in the prepupal
stage bas suffered no change in external structure, it still
wears the larval skin, and its visible difference f?om the
active larva is a mere alteration in form. Internally, how-
ever, important reconstructive processes are now taking
place.
The internal activities of reconstruction, which bring
about the pupal metamorphosis of the larva to the adult,
begin at the head end of the insect and progress poste-
riorly. They are preceded bv a loosening and subsequent
detachment of the larval cuticula from rhe cellular layer
of the skin, or epidermis, beneath it. The latter, known
also as the h)'podermis, freed now from restraint, enters a
period of rapid growth. On the head, the head walls are
remodeled and take on a new form, and new antennae and
new mouth parts are produced. The new structures bave
no regard for the forms of the old, though each is pro-
duced from a part of the corresponding larval organ. The
new antennae, for example, are formed from the larval
antennae, but the antennae of the moth are to be much
larger than those of the caterpillar. Only the tip, there-
fore, of each new organ can be formed within the cuticular
sheath of the old; the base pushes inward, and rhe don-
gating shaft folds against the face of the newly forming
head. The saine thing is true of the maxillae and labium,
but in the case of the mandibles the procedure is simpler,
for the jaws are to be reduced in the moth. The epi-
dermal core of each mandible, therefore, simply shrinks
within the cuticular sheath of the larval organ, leaving
the cavity of the latter almost empty.
As the separation of the cuticula from the epidermis
progresses over the region of the thorax and a free space
is created between the two layers, the wing buds, which
heretofore bave been turned inside the caterpillar's body,
now evert and corne to be external appendages of the pupal
body though still covered by the curicula of the larva
(Fig. 59 C, I/es, I¢"a). The legs of the moth pupa are
[ 295 ]
INSECTS
formed in the saine way as are the antennae and the mouth
parts, that is, they are developed from the epidermis of
the corresponding larval legs; but, by reason of their
creased size, they are forced to bend upward against the
sides of the bodv of the pupa, and, when fully formed,
each is round to bave onlv its terminal part within the
cuticular sheath of the leg of the caterpillar.
From the thorax, the loosening of the cuticula spreads
backward over the abdomen, until at last the entire insect
lies ffee within the cuticular skin of the caterpillar. The
so-called prepupal period of the caterpillar, therefore, is
scarcelv to be regarded as a trulv larval stage of the in-
sect. it is still clothed in the larval cuticula, and retains
externallv ail the structural characters of the larva; but
the creature itself is ira a first growth period of the pupal
stage, and may appropriately be designated a propupa.
When the cuticula is separated flore the epidermis ail
over the body, it may be cut open and taken off without
injury to the wearer. The latter, now a propupa (Fig.
59 C), is then discovered to be a thing entirely different
in appearance flore the caterpillar. It bas a small head
bent downward, a thoracic region of three segments, and
a large abdomen. The head bears the mouth parts and a
pair of large antennae (4nt) ; the thorax carries the wings
(IFs, II.') and the legs (L), which latter are much longer
than those of the caterpillar, but, being folded beneath
the wings, only their ends are visible in side view. The
abdomen consists of ten segments and bas lost ail ves-
tiges of the abdominal legs of the caterpillar (A, .4L).
Many important changes bave taken place ira the form
and structure of the head and in the appendages about
the mouth during the change from the caterpillar to the
propupa, as may be seen by comparing Figure 59 H, with
Figure I5'. Most of the lateral areas of the caterpillar's
head (Fig. 5), including the region of the six small eyes
on each side, have been converted into the two huge eye
areas of the pupa (Fig. I59 H, E), which cover the develop-
[ 9 6 ]
THE CATERPII.LAR AND THE MOTH
ing compound eves of the adult. The antennae (.4nt), as
alreadv noted, Jaave increased greatly in size, and thev
show evidence of their future multiple segmentation.
The upper lip, or labrum (Lin), on the other hand, is much
smaller in the propupa than in the caterpillar, and the
great biting jaws of the caterpillar are reduced to mere
rudiments in the propupa (Md), while the spinneret (Fig.
152 , 5'pt) is gone entirely. The labium and the two
maxillae are longer and more distinct from each other in
the propupa (Fig. 159 H, Lb, Mx) than in the caterpillar,
and their parts are somewhat more simplified. The
labium bears two prominent palpi (LbPlp).
The remodeling in the external form .of the insect pro-
ceeds from particular groups of cells in the epidermis,
cells that bave remained inactive since the time of the
embryo, and which, as a consequence, retain an unused
vitalitv. These groups of regenerative epidermal cells,
which'are the histoblasts, or imaginal discs, of the body
wall, bave hot been particularly studied in the caterpillar;
but in certain other insects thev have been round to occur
in each segment, typically a pair of them on each side of
the back: and a pair on each side of the ventral surface.
At the beginning of metamorphosis, as the larval cuticula
separates from the epidermis, the cells of the discs multiply
and spread from their several centers, and the areas newlv
formed bv them takeon the contour and structure of the
pupa ins{ead of that of the larva. The old cells of the
larval epidermis, which have reached the limits of their
growing powers and are now in a state of senescence, give
wav before the advancing ranks of invading cells; their
tisues go into dissolution and are absorbed into the body.
The new epidermal areas finallv meet and unite, and to-
gether cons-titute the body wallof the pupa.
While the new epidermis is giving external form to the
pupa beneath the larval cuticula, its cells are generating
a new pupal cuticula. As long as the latter is sort and
plastic the cell growth may proceed, but when the cutic-
[ =97 ]
INSECTS
ular substance begins to harden; growth ceases, and the
external form of the insect will henceforth show no further
change in its structural features.
The propupa of the nnoth rennains for several days a
soft-skinned creat'ure I Fig. 59 C) inside the cuticula of
the larva, during which tinne its body contracts in size and
its wings, legs, antennae, and nnaxilloe lengthen. The wings
are flattened against the sides of the body, and the other
appendages are applied close to the under surface. Then
a gluelike substance is exuded fronn the body wall, which
fixes the nnennbers in their positions and soon dries into a
hard coating or glaze over the body and appendages, giving
to the whole a shell-like covering. In this way the sort
propupa (C beconnes a chrvsalis (D). Finally, the old
caterpillar skin splits along the back of the first two body
segnnents, over the top of the head, and down the right side
of the facial triangle. The p.upa now quickly wriggles out
of the enclosing skin and pushes the latter over the rear
extrennity of its body into the end of the cocoon, where it
rennains as a shriveled mass, the last evidence of the
caterpillar.
The pupa, or chrysalis, of the tent caterpillar I Fig.
59 D) is nnuch snnaller than the propupa (C), and its
length is only about one-third that of the original cater-
pillar (A). The color of the chrysalis is at first bright
green on the fore parts, yellowish on the abdonnen, and
usually nnore or less brown on the back. Soon, however,
the color darkens until the front parts and the wings are
purplish black, and the abdonnen purplish brown. Though
the covering of the chrysalis is hard and rigid, the creature
is still capable of a very active wriggling of the abdonnen,
for three of its intersegnnental rings rennain flexible. By
this provision the pupa is able to divest itself of the larval
skin. The pupoe of sonne species of nnoths push thenn-
selves partly out of the cocoon just before the tinne of
transfornnation to the nnoth, and when the latter ennerges
[ 9 8 ]
THE CATERPII.LAR AND THE MOTH
it leaves the pupal skin projecting from the mouth of the
cocoon (Plate I2).
Concurrent with the remodeling in the external form of
the insect, other changes bave been taking place within the
body. The first of the complicated metamorphic processes
that affect the inner organs occurs in the stomach, where,
as we have already observed, the inner wall is cast off at
about the time that the caterpillar begins the spinning of
its cocoon. This shedding of the stomach lining is quite a
different thing from the molting of an external cuticula,
for the StOlnach wall is a cellular tissue. Furthermore,
wherever other cell lavers are discarded, as in the case of
the epidermis, the cells are absorbed Mto the body cat, ity.
A new stomach wall is generated usually from groups of
small cells that originally lay outside the old wall and were
retained when the latter was cast off. These cells, as do
the imaginal discs of the epidermis, form a new lining.to
the stomach and give a new shape to this organ, which in
the adult insect mav be quite different from that of the
larva. The sheddin of the stomach wall is hot necessarily
a part of the metamorphosis, for in some insects and in
certain other related animals, it is said, the stomach
epithelium as well as the cuticular lining is shed and
renewed with each molt of the bodv wall.
The parts of the alimentarv canal that lie before and
behind the stomach, that is, the oesophagus and crop
(Fig. 154, Oe, Cr) and the intestine (It), formed in the
embrvo as ingrowths of the bodv. wall, are regenerated
from groups of cells in their walls in the saine manner as is
the epidermis itself, the old cells being absorbed into the
bodv. The cuticular linings of these parts are shed with
the Cuticula of the bodv wall at the time of the molt. The
complete alimentarv canal of the moth is verv different
from that of the caterpillar, as will be shown in the next
section of this chapter/Fig. 164).
The walls of the Malpighian tubules are said to be
regenerated in some insects, but the tubules do hot change
[ =99 ]
INSECTS
much in form in the moth, and they continue their ex-
cretorv function during the pupal stage. The silk glands
of the caterpillar are greatly reduced in size, and their
ducts, as a consequence of the suppression of the spinneret,
open at the base of the labium within the entrance to the
mouth.
lnternal organs that bave hot been specially modified
in their development for the purposes of the larva, in-
c]uding usually the nervous system, the heart, the respira-
tory tubes, and the reproductive organs, surfer little if any
disntegration in their tissues; they simply grow to the
mature form, which may be much more elaborate than
that of the larva, bv a resumption of the ordinary processes
of development. The nervous system, and particularly
the tracheal system, however, in some insects undergo
much reconstruction between the larval and the adult
stages.
A most important part of the reconstruction between
the larva and the adult has to do with the muscle system.
Since, in its two active stages, the insect leads usually
two verv different lires, the mechanism of locomotion is
likely to be radicaliv different in the larva and in the
adult; and in such cases the transformation of the insect
will involve particularly a thorough reorganization of the
musculature. Most larvae have acquired an elaborate
system of speciai muscles for their own use because they
have adopted a wormlike mode of progression. On the
other hand, the adults have need of certain muscles, par-
ticularlv those of the wings, which would be only an en-
cumbrance to a larva. Consequently, muscles needed only
by the adult are suppressed in the larval stage, and the
special muscles of the larva must be cleared away during
the pupal stage. The metamorphosis in the muscle sys-
rem, therefore, varies much in different insects according
to the mechanical difference between the larva and the
aduit.
The purely larval muscles that are to be discarded when
[3ool
THE CATERPILLAR AND THE MOTH
their purpose has been accomplished go into a state of dis-
solution during the pupal period. The débris of their
tissues is thrown into the blood, from which it is later ab-
sorbed as nutriment by the newly forming organs. The
caterpillar has a very elaborate system of muscles forming
a complicated network of fibers against the inner surface
of the body wall, some running longitudinally, others
transversely, and still others obliquely. Most of the
transverse and oblique fibers are hOt retained in the moth,
and if specimens of those muscles are examined during the
early part of the pupal period they are seen to have a weak
and abnormal appearance; the structure typical of healthy
muscle tissue is obscure or indistinctly evident in them,
and in places they are covered with groups of free oral
cells. These cells are probably p/mgocytes.
A phagocyte is a blood corpuscle that destroys foreign
proteid bodies in the blood, or any unhealthy tissue of the
body. It is hot probable that the insect phagocytes are
the active cause of the destruction of the larval tissues, but
they do engulf and digest particles of the degenerating
tissues. They are present in large numbers in some insects
during metamorphosis, and are scarce or lacking in others.
The decadent state of the larval tissues that have passed
their period of activity lays them open to the attack of
the phagocytes, but these tissues will go into dissolution
by the solvent powers of the blood alone. Active, healthy
tissues are always immune from phagocytes.
Some of the larval muscles may go over intact to the
adult stage, and others may require only a remodeling
or an addition of fibers to make them serviceable for the
purposes of the adult. The adult muscles that are com-
pletely suppressed during the larval stage appear to be
generated anew during the pupal stage. There is a dif-
ference of opinion among investigators as to how the new
muscles are developed, but it is probable that they take
their origin from the saine tissues that built up the larval
muscles.
[ 3Ol ]
INSECTS
The development of the internal organs proceeds with-
out interruption from the beginning of the propupal period
until the adult organs are c.ompleted at the end ofthe pupal
stage. The external parts, however, do hot make a con-
tinuous growth. After reaching a certain stage of de-
velopment, the form of the body wall and of the append-
ages is fixed by the hardening of the new cuticula on
their outer surfaces. In this stage, therefore, thev must
remain, and the half-mature form attained is that char-
acteristic of the pupa. The final development of the body
wall and the appendages of the adult is accomplished by
a second separation of the epidermis from the cuticula,
which allows the cellular layers, now protected by the
pupal cuticula, to go through a second period of growth
during the pupal stage. This pupal period of growth at
last results in the perfection of the external characters
of the adult, which are in turn fixed by the formation of
the adult cuticula. In the meantime, the new muscles
that are to be retained have become anchored at their
ends into the new cuticula, and the mechanism of the
adult insect is ready for action. The perfect insect,
cramped within the pupal shell, has now only to await
the proper time for its emergence.
Through the whole period of metamorphosis, the insect
must depend on its internal resources for food materials.
Oxygen it can obtain bv the usual method, for its respira-
tory system remains functional; but in the matter of
food it is in a state of complete blockade. The pupa bas
two sources of nourishment: first., the food reserves stored
in the cells of the fat-body; second, the materials resulting
from the breaking down of the larval tissues, which are
scattered in the blood and eventually absorbed.
The fat cells, at the beginning of metamorphosis in some
insects, give up most of their stored fat and glycogen; and
they now become filled with small granules of proteid
matter. The proteid granules are probably elaborated in
the fat cells from the absorbed detritus of the larval
[ 3o: l
THE CATERPII.LAR AND THE MOTH
organs by means of enzymes produced in the nuclei of the
cells. The fat cells thus take on the function of a stomach,
converting the materials dissolved in the blood into forms
that the growing tissues can assimilate. During this time
the masses of fat tissue that compose the fat-body of the
"r<>:,.ç::o " :-:oE--: :¢.,' / e
I. ,/"   é "... " "/""   O-
" .- --.--..:»" :e«::.a«  <çi::.-:: O Fro. 6o. Bodies in the blood of a young pupa of the tent cterpillar a, a free fat cell, containing large oily fat globules, and small proteid granules; b, r, fat cells in dissolution; d, froe proteid granules in the blœed, and e, fat globules liberat from the disintegrating fat cells;f, blœed corpuscles larva have broken up into free cells, and these cells, vacuolated with oii globules and later charged with pro- teid granules, now fill the blood. The interior of the moth pupa, or chrysalis, shortly after the larval skin is shed, contains a thick, yellow, creamv liquid. In it there mav be discovered, however, the ali'mentarv tract, the nervous system, and the tracheal tubes, the latter filled with air; but all these parts are so soft and delicate that thev can scarcelv be studied by ordinarv methods of dissecion. The creamy pulp of the pupa's body, when examined under the microscope, is seen to consist of a clear, pale, amber-vellowish liquid full of small bodies of various sizes (.1Oig. 6o), which give it the opaque appearance and thick consistencv. The liquid medium is the blood, or bodv lymph. Tle largest bodies in it are free fat cells (a); sma'ller ones are probably blood corpuscles (f); and the [303] INSECTS finest matter consists of great quantities of minute grains (d) floating about separately or adhering in irregular masses. Besides these etements there are many droplets of oil (e), recognizable by their smooth spherical outlines and golden-brown color. The fat cells are mostlv irregu- larly ovoid or elliptical in shape; their protoplasm is filled with large and small oil globules, and contains also masses of fine granules like those floating free in the blood. These granules are the protoplasmic substances formed within the fat cells. Many of the cells have irregular or broken out- lines (b, c), as if their outer walls had been partly dis- solved, and the contents of such cells appear to be escap- ing from them. In fact, manv are clearly in a state of dis- solution, discharging both thëir oil globules and their pro- teid inclusions into the blood; and it is clear that the similar matter scattered so profusely through the blood liquid has corne from fat cells that have alreadv disin- tegrated. Ail these materials will gradually be consumed in the building of the tissues of the adult, the organs of which are now in process of formation. In Chapter IV we learned that every animal consists of a body, or soma, formed of cells that are differentiated from the germ cells usually at an early stage of develop- ment. The function of the soma is to give the germ cells the best chance of accomplishing their purpose. An insect that goes through two active forms during its life, a larval and an adult form, differs from other animais in having a do«ble soma. The entire organism, of course, is hot double, for, as we bave just seen in the study of the caterpillar, many of the more vital organs are continuous from the larva to the adult; but there is a group of organs which, after reaching a definite form of development in the larval stage, at the end of this stage virtually die and go into dissolution, while a new set of tissues develops into new organs or into new tissues replacing those that have been lost. The groups of somatic cells that-form the tissues and organs that undergo a metamorphosis, there- [304] THE CATERPILLAR AND THE MOTH fore, are differentiated in the embryo into two sets of cells, one set of which will form the special organs of the larva, while those of the other will remain dormant during the larval life to form the adult organs when the larval cells have completed their functions. The cells of the second set carry the hereditary influences that will cause them to develop into the original, or ancestral, form of the species; the cells of the first set produce the temporary larval form, which mav retain certain primitive characters from the embryonic stage, but which does not represent an ancestral form in the evolution of the species. An extreme case of anything is always more easily understood when we can trace it back to something simple, or link it up with something familiar. The metamorphosis of insects appears to be one of the great mvsteries of nature, but reduced to its simplest terres it becomes only an exaggerated case of a temporary growth in certain groups of cells to form something of use to the young, which disappears by resorption when the occasion for its use is past. Innumerable simple cases of this kind might be cited from insects; but there is a familiar case of well- developed metamorphosis even in our own growth, namely, the temporary development of the milk teeth and their later substitution by the adult teeth. If a similar process of double growth from the somatic cells had been carried to other organs, we ourselves should have a meta- morphosis entirely comparable with that of insects. TIaE Mo'rla For three weeks or a little longer the processes of re- construction go on within the pupa of the tent caterpillar, and then the creature that was a caterpillar breaks through its coverings and appears in the form and costume of a moth (Fig. I59 J). The pupal shell splits open on the forward part of the back (E) to allow the moth to emerge, but the latter then only finds itself face to face with the wall of the cocoon. It has left behind its cutting instru- [ 305 ] INSECTS ments, the mandibles, with its discarded overalls; but it bas turned chemist and needs no tools. The glands that furnished the silk for the larva bave shrunken in size and bave taken on a new function; they now secrete a clear liquid that oozes out of the mouth of the moth and acts as a solvent on the adhesive surfaces of the cocoon threads. The strands thus moistened are soon loosened from one another suflqcientlv to allow the moth to poke its head through the cocoon wall and force a hole large enough to permit of its escape. The liquid from the mouth of the moth turns the silk of the cocoon brown, and the lips of the emergence hole are alwavs stained the saine color - evidence that it is this liquit that softens the silk--and the fraved edges of the hole left in the cocoon of the tent caterpillar show manv loose ends of threads broken by the moth in its exit. The most conspictu)us features of the moth (Fig. 6) are its furrv covering of hairlike scales and its wings. The wings are short when the insect first emerges from its cocoon (Fig. 159 J), but they quickly expand to normal length and are then folded over the back IFig. 16 A). The colors of the moths of the tent caterpillar are various shades of reddish-brown with two pale bands obliquely crossing the wings (Plate 14 G, H). The female moth (Plate 4 H, Fig. 16 B) is somewhat larger than the maie, ber body being a little over three-fourths of an inch in length, and the expanded wings one and three-fourths inches across. The tent caterpillars perform so thoroughly their dutv of eating that the moths have little need of more food. Consequently the moths are hot encumbered with imple- ments of feeding. The mandibles, which were such large and important organs in the caterpillar (Fig. 52, Md) but which shrank to a rudimentary condition in the pro- pupa (Fig. I59 H, J/d), are gone entirely in the moth (Fig. I6). The maxillae, which were fairly long lobes in the propupa (Fig. 59 H, Mx), have likewise been [ 306 ] THE CATERPILI.AR AND THE MOTH reduced to mere rudiments in the adult, where they appear as two insignificant though movable knobs (Fig. 162, Mx). The median part of the labium has been reduced to almost nothing in the moth; but the labial palpi (LbPlp) are long and three-segmented, and when normally covered with hairlike scales thev form two conspicuous feathery brushes that project in front of the face. The mouth parts of the tent caterpillar moth are hOt typical of these organs of moths and butterflies in gen- Fro. 6. Moths ofthe tent caterpillar, Malacosoma americana. (A little greater than natural size) eral, for most of these insects are provided with a long proboscis bv means of which they are able to feed on liquids. Evervone is familiar with the large humming- bird moths, or'hawk moths, that are to be seen on sumnaer evenings as thev dart from flower to flower, thrusting into each corolla a long tube uncoiled from beneath the head; and we have ail seen the sunlight-loving butterflies carelesslv flitting over the flower beds, alighting here and there on attractive blooms to sip the sweet liquid from the nectar cups. Moths and butterflies carry the proboscis tightly coiled, like a tinv watch spring (Fig. I63 A, Prb), be- neath the head and just behind the mouth. It can be unwound and extended (B, Prb) whenever the insect wants to extract a drop of nectar from the depths of a [ 307 ] INSECTS  -- flower corolla, or when it  would merely take a drink of water or other liquid. The proboscis consists of the greatly lengthened maxillae firmlv attached to each other by dovetailed grooves and • ", ridges. The inner face of tlf / each maxilla is hollowed in the form of a groove run-  kQ -Z//IP ning its entire length' and the two apposed grooves FIG. 162. Facial view of the head of between the united maxillae the tent caterpillar moth, with cover- are converted into a central ing scales removed, and antennae cut channel of the proboscis. off near their bases tl,,t, base of antenna; E, compound The two blades of the pro- eye; Lb, labium; LbPIp, labial palpus; boscis spring from the sides Lm, labrum;Mth, mouth;Mx, maxilla of the mouth. The first part of the alimentary canal just back of the mouth is transformed into a bulblike sucking apparatus. The Fro. 163. Head and mouth parts of the peach borer moth A, side view. B, three-quarter facial view. /lnt, basal part of antenna; E, compound eye; LbPlp, labial palpus; O, ocellus; Prb, proboscis l 308 ] THE CATERPILLAR AND THE MOTH upper wall of the structure is ordinarily collapsed into the cavity of the bulb, but itis capable of being lifted by strong muscles inserted upon it from the walls of the head. The alternate opening and closing of the bulb sucks the liquid food up through the tube of the pro- boscis and forces it back into the gullet. The moths and butterflies are thus sucking insects, as are the aphids and cicadas, but they are hot provided with piercing organs, though some species have a rasp at the end of the pro- boscis which is said to enable them to obtain juices from soft-skinned fruits. ,Vith the tent caterpillar, it is interesting to note, the maxillae are much longer in the pupa (Fig. I59 I, Mx) than thev are in either the caterpillar or the adult moth (Fig. I62, Mx), as if nature had intended the tent cater- pillar moth to have a proboscis like that of other moths, but had then changed her mind. The real meaning of this is that the moths of the present-day tent cater- pillars are descended from ancestors that had a functional proboscis in the adult stage like that of other moths, and that the reduction of the proboscis of the modern moths has taken place in rimes so recent that the organ has hot vet been suppressed to the saine degree in the pupa. The alimentary tract of the tent caterpillar moth is verv different from that of the caterpillar. In the cater- piller, the organ consists of three principal parts (Fig. J64 A), the first comprising the oesophagus (Oe) and the crop (.Cr), the second being the stomach, or ventriculus (lZent), and the third the intestine (Int). In an adult moth that is almost mature, but which is still inside the pupal shell (B), the oesophagus bas become a long narrow tube IOe) at the rear end of which the crop forms a small sac (Cr) projecting upward, which mav contain a bubble of gas. The stomach has contracted to a pear-shaped bag with verv thin transparent walls, and is usually filled with a t{ark-brown liquid. The intestine has changed radically in form, for it now consists of a long, slender, [ 309 ] INSECTS tubular part, the small intestine (SDt), and of a great terminal receptacle, the rectum (Rert), filled with a mass of soft orange-colored marrer. In the fully-matured insect (C), after it has escaped from the cocoon, still fu,'ther C  8Int FiG. I64. Transformation in the form of the alimentary canal of the tent caterpillar from the larva to the adult moth A, alimentary canal of the caterpillar. B, the saine of the pupa. C, the saine of the moth Cr, crop; Int, intestine; Mal, Malpighian tubules (hOt shown full length); Oe, oesophagus; Rect, rectum; Slnt, small intestine; lent, centriculus alterations bave taken place. The crop sac (Cr) is now greatly distended into a spherical vesicle tensely filled wlth gas--air, probably, that the moth has swallowed, perhaps to aid it in breaking the pupal shell, for there are sometlmes small bubbles also in the tubular oesophagus. [31o] THE CATERPII.I.AR AND THE MOTH The stomach is contracted to a mere remnant of its former size (A, l'ent), and its walls are thrown into thick corrugations. The intestine (SI,t) is about the saine as in the earlier stage of the moth (B). Since the moth of the tent caterpillar probably eats nothing, it has little use for a stomach. The intestine, however, must serve as an outlet for the lalpighian tubules (Mal), since the latter remain functional through the pupal stage. The secretion of the tubules contains great numbers of minute spherical crystals, which accunqu- late in the rectal sac (Rect) where thev form the orange- colored mass contained in this organ and discharged as soon as the moth leaves the cocoon. Most of the maie moths of the tent caterpillar emerge from the cocoons several davs in advance of the females. At this time their bodies contain an abundance of fat which fills the cells of the fat tissue as droplets of oil. This fat is probably an energy-forming reserve which the maie moth inherits from the caterpillar, for the internal reproductive organs are hOt vet fullv developed and do hOt become functional until "about the time the females are out of their cocoons. The bodies of the female tent caterpillar moths, on the other hand, contain little or no fat tissue; but each female is fully matured when she emerges from the cocoon, and ber ovaries are full of ripe eggs readv to be laid as mon as the fertilizing element is received from the male (Fig. I65, Or). The spermatozoa will be stored in a special recep- tacle, the spermatheca (Spm), which is connected with the exit duct of the ovaries (I'Ç¢) by a short tube. Each egg is then fertilized as it issues from the oviduct. The ma- terial that will form the covering of the eggs when laid is a clear, brown liquid contained in two great sacs (Fig. 65, Res) that open into the end of the median oviduct (lg). Each sac is the reservoir of a long tubular gland (C/G/). The liquid must be somehow mixed with air when it is discharged over the eggs to give the egg covering [311] IN  ECTS its ffothy texture. It soon sets into a jellylike substance, then becomes firm and elastic like soif rubber, and finally turns drv and brittle. The d'are of the egg laying depends on the latitude of the region the moths inhabit, varying flore the middle Spm Bcpx Dov VF b An Fro. 16 5. The female reproductive organs of the moth of the tent caterpillar, as seen from the left side a, external opening of the bursa copulatrix; .4n, anus; b, opening of the vagina; Bcpx, bursa copulatrix; CIGI, colleterial glands, which form the substance of the egg covering; Dot', duct of the left ovary; upper ends of the ovarian tu bules; Rect, rectum; Res, reservoirs of the colleterial glands (CIGI); 8pro, spermatheca, a sac for the storage of the spermatozoa; ri. terminal strand of the ovary; I/g, vagina of Mav in the southern States to the end of June or later in the north. While the eggs will hot hatch until the fol- lowing spring, they nevertheless begin to develop at once, and within six weeks young caterpillars may be round fldly formed within them (Fig. 166 B). Ech little caterpillar has its head against the top of the shell and its body bent U-shaped, with the tail end turned a little to one side. The long hairs of the body are ail turned for- ward and form a rhin cushion about the poor creature, which for crimes yet uncommitted is sentenced to eight [3] THE CATERPILLAR AND THE MOTH months' solitary confinement in this most inhuman posi- tion. Yet, if artificially liberated, the prisoner takes no advantage of the freedom offered. TlSough it can move a little, it remains coiled (A) and will fold up again if forcibly straightened, thus asserting that it is more com- fortable than it looks. It is surprising that these infant caterpillars can remain inactive in their eggshells ail through the summer, when the warmth spurs the vitality of other species and speeds them up to their most rapid growth and development. External conditions in general appear to have much to do with regulating the lives of insects, and if the tent caterpillars in their eggs seem to give proof that the crea- tures are hOt entirely the slaves of environ- ment, the truth is probably that ail in- sects are hOt gov- erned bv the saine Fro. 166. The young tent caterpillar fully formed within the egg by the middle of summer A, the young caterpillar removed from the egg. B, the caterpillar in natural position within the egg conditions. We have seen that some of the grasshoppers and some of the aphids will hot complete their develop- ment except after being subjected to freezing tempera- tures, and so it probably is with the tent caterpillars-- it is hot warmth, but a period of cold that furnishes the condition necessary to the final completion of their de-- velopment. Whatever mav.be the secret source of their patience, however, the young tent caterpillars will bide their time through ail the heat of summer, the cold of winter, and hot till the buds of the cherry or apple leaves are ready to open the following spring will they awake and gnaw through the inclosing shells against which their faces have been pressing ail this while. [313] CHAPTER X MOSQUITOES AND FLIES TlqOIJGI-ITFUL persons are much given to pondering on what is to be the outcome of our present age of intensive mechanical development. Thinking, the writer holds, is ail right as a means of diverting the mind from other things, but those who make a practice or a profession of it should follow the example of that famous thinker of Rodin's, who has consistently preserved a most com- mendable silence as to the nature of his thoughts. We can all admire thinking in the abstract; it is the expression ofthoughts that disturbs us. So it is that we are troubled when the philosophers.warn us that the develo.pment of mechanical proficiency is hot synonymous with advance- ment of true civilization. However, it is hot for an entomologist to enter into a discussion of such matters, because an observer untrained in the study of human affairs is as likely as hot to get the impression that only a very small percentage of the present human population of the world is devoted to efficiency in things mechanical or otherwise. There is no better piece of advice for general observance than that which admonishes the cobbler to stick to his last, and the maxim certainly implies that the entomolo- gist should confine himself to his insects. However, we can hot help but remark how often parallelisms are to be discovered between things in the insect world and affairs in the human world. So, now, when we look to the insects for evidence of the effect of mechanical perfection, we observe with somewhat of a shock that those very insect 1341 MOSU1TOES AND FI.IES species which unquestionably have gone farthest along the road of mechanical eflïciencv bave produced little else commendable. In this class we would place the mos- quitoes and the flies; and who will say that either mosqui- toes or flies bave added anything to the comfort or enjoy- ment of the other creatures of the world? Reviewing brieflv the esthetic contributions of the major groups of insccts, we find that the grasshoppers bave produced a tribe of musicians; the sucking bugs bave evolved the cicada; the beetles bave given us the scarab, the glow-worm, and the firefly; the moths and butterflies have enriched the world with elegance and beauty; to the order of the wasps we are indebted for the honeybee. But, as for the flies, they bave generated only a great multitude of files, amongst which are included some of our most obnoxious insect pests. However, in nature study we do hot criticize; we derive our satisfaction from merely knowing things as they are. If out subject is mosquitoes and flies, we look for that which is of interest in the lires and structure of these insects. FLIES IN GENERAL The mosquitoes and the flies belong to trie saine ento- mological order. That which distinguishes them princi- pally as an order of insects is the possession of only one pair of wings (Fig. 67). Entomologists, for this reason, call the mosquitoes and files and ail related insects the Diptera, a word that signifies by its Greek components "two wings." Since nearly ail other winged insects have four wings, it is most probable that the ancestors of the winged insects, including the Diptera, had likewise two pairs of wings. The Diptera, therefore, are insects that bave become specialized primarily during their evolution by the loss of one pair of wings. We shall now proceed to show that the evolution of a two-winged condition from one of four wings bas been a [,315] INSECTS progress toward greater efficiencv in the mechanism of flight, and that the acme in this Il'ne has been attained by the files and mosquitoes. The truth of this contention will become apparent when we compare the relative development of the wings and the manner or effective- ness of flight in the several principal orders of insects. Fro. 16 7. A robber fly, showing the typical structure of any member of the order Diptera The files are two-winged insects, the hind wings belng reduced to a pair of knobbed stalks, the halteres (H1) It is most probable that when insects first acquired wings the two pairs were alike in both size and form. The termites (Fig. 168 A) afford a good example of in- sects in which the two pairs of wings are still almost identical. Though the termites are poor flyers, their weak- ness of flight is hot necessarilv to be attributed to the form of the wings, because their wing muscles are partially degenerate. The dragonflies (Fig. 58) are particularly strong flyers, and with them the two pairs of wings are but little different in size and form; but the dragonflies [316l MOSQUITOES AND FI.IES are provided with sets of highly developed wing muscles which are much more effective than those of other insects. From these examples, therefore, we can hot well judge of the mechanical eflîciencv of two pairs of equal wings moved by the equipment of muscles possessed by most " E1 C  Fro. 168. Evolution of the wings of insects A, wings of a termite, approximately the saine in size and shape. B, wings of a katydid, the hind wings are the principal organs of flight. C, wings of a beetle, the fore wings changed to protective sheIIs, elytra (El), covering the hind wings. D, wings of a hawk moth, united by the spine (f), which is held in a hook on under surface of fore wing. E, wings of the honeybee, held together by hooks (h) on edge of hind wing. F, wing of a blowfly, and the rudimentary hind wing, or halter (HI) [317] INSECTS insects; but it is evident that the majority of insects bave round it more advantageous to bave the fore and hind wings different in one wav or another. In the grasshoppers, it was o'bserved (Fig. 63) , the hind wings are expanded into broad membranous fans, while the fore wings are slenderer and of a leatherv texture. The saine is truc of the roaches (Fig. 53), the katydids IFig. 68 BI, and the crickets, except in special cases where the fore wings :tre enlarged in the maie to form musical organs (Fig. 39). In ail these insects the hind wings are the principal organs of flight. \Vhen hot in use thev are filded over the bodv beneath the fore wings, which latter serve then as protective coverings for the more delicate hind wings. In the beetles Figs. 37, 6 C) the hind wings :tre much largcr than the fore wings, and, as with the grasshppers and their kind, thev take the chier part in the function of ttight. The beetles, however, bave carried the idea of converting the fore wings into pro- tective shields fir the hind wings a little farther than have the grasshoppers; with them the fore wings are usuallv hard, shell-like flaps that fit together in a straight line over the back (Fig. 37 A), forming a case that completely conceals, ordinarilv, the membranous hind wings folded beneath them. Neither the grasshoppers nor the beetles :tre swift or partictdarly eflScient flyers, but thev appear to demonstrate that the ordinarv insect mechanism of flight is more effective with one pai of wings than with two. The buttertties and the moths use both pairs, of wings in flight; but with these insects, it is to be noted, thefront wings are always the larger IFig. 68 I)). The buttertties, with four broad wings, ttv well in their wav and are ca- pable of long-sustained tight, though the); are compara- tively slow goers. Some of the moths do much better in the marrer ofspeed, but it is round that the faster flying species bave the fore wings highly devcloped at the ex- pense of the hind wingsç and that the two wings on each side, furthermore, are voked together in such a manner as [3q ] MOSQUITOES AND FI.IES to insure their acting as a single wing (D). The moths clearlv show, therefore, as do the grasshoppers and the beetles, the eRiciency of a single pair of flight organs as opposed to two. "lhe moths, however, have attacked from a different angle the problem of converting their in- herited equipment of four wings into a two-wing mecha- nism--instead of suppressing the flight function in one pair of wings, they have given a mechanical unity to the two wings of each side, thus attaining functionally a two- winged condition. The wasps (Fig. 1,3,3) and bees, likewise, have evolved a two-winged machine from a four-wing mechanism on the principle of uniting the two wings on each side. The bees have adopted a particularly efficient method of securing the wings to each other, for each hind wing is fastened to the wing in front of it bv a series of small hooklets on its anterior rein that grasp a marginal thickening on the rear edge of the front wing (Fig. 1618 E). Moreover, the bees bave so highly perfected the unitv in the design of the wings that only on close inspectio] % it to be seen that there are actuallv two wings on each side of the body. Finally, the f]ies, including ail members of the order Diptera, have boldly executed the toaster stroke by com- pletely eliminating the second pair of wings from the mechanism of flight. The files are literally two-winged insects (Figs. 67, 68 F). Remnants of the hind wings, it is true, persist in the form of a pair of small stalks, each with a swelling at the end, projecting from behind the bases of the wings (Figs. 67, 68 F, HI). These stalks are known as "balancers," or halteres, and in their structure they preserve certain features that show them to be rudiments of wings. The giving over of the function of flight to the front pair of wings has necessarily involved a reconstruction in the entire framework and lmsculature of the thorax, and a study of the fly thorax gives a most interesting and in- structive lesson in the possibilities of adaptive evolution, [319] INSECTS showing how a primitive ancestral mechanism may be entirely remodeled to serve in a new capacity. If the flies had been specially "created," and hot evolved, their structure could bave been much more directly fitted to their needs. Itis hot only in the matter of wings and the method of flight that the flies show they are highly evolved insects; p B Flc. 16 9. The black horsefly, Tabanus atratus A, the entire fly. B, facial view ofthe head and mouth parts. Int, antenna; 7, 7, compound eyes; Lb, ]abium; Lin, labrurn: AId, rnandible; Mx, maxilla; MxPlp, maxillary palpus they are equally specialized in the structure of their mouth parts and in their manner of feeding. The flies subsist on liquid food. Those species that can satisfy their wants from liquids freely accessible bave the mouth parts formed for sucking only. Unfortunately, however, as we all too well know, there are many species that demand, and usu- ally obtain, the fresh blood of mammals, including that of man, and such species have most efficient organs for piercing the skin of their victims. The most familiar examples of flies that "bite" are the mosquitoes and horseflies. The horseflies (Fig. J6 9 A), some of which are called also gadflies and deer flies, belong to the familv Tabanidae. An examination of the head of [3o ] MOS.QUITOES AND FIAES the common large black horsefly (Fig. I69 B) will show the nature of the feeding organs with which these flies are equipped. Projecting downward from the lower part of the head are a numberof appendages; these are the mouth parts. They correspond in number and in relative posi- tion with the mouth appendages of the grasshopper (Fig. 66), but they differ from the latter very much in form because they are adapted to quite a different manner of feeding. The horsefly does hot truly bite; it pierces the skin of its victim and sucks up the exuding blood. By spreading apart the various pieces that compose the group of mouth parts of the horsefly, it will be seen that there are nine of them in ail. Three are median in posi- tion, and therefore single, but the remaining six occur in duplicate on the two sides, forming thus three sets of paired structures. The large club-shaped pieces, how- ever, that lie at the sides of the others, are attached at their bases to the second paired organs and constitute a part of the latter, so that there are really only two sets of paired organs. The anteriormost single piece is the labrum (Fig. 169 B, Lin); the first paired organs are the mandibles (Md); the second are the maxillae (Mx); the second median piece is the hypopharynx (hot seen in Fig. 169 B); and the large, unpaired, hindmost organ is the labium (Lb). The lateral club-shaped pieces are the palpi of the maxillae (lI.vPlp). The labrum is a strong, broad appendage projecting downward from the lower edge of the face (Figs. I6 9 B, 17o A, Lin). lts extremity is tapering, but the tip is bhmt; its under surface is traversed by a median groove extending from the tip to the base but closed normally by the hypopharynx (Fig. I7O D, Hp_v), which fits against the under side of the labrum and converts the groove into a tube. The upper end of this tube leads directly into the mouth, a small aperture situated between the base of the labrum and the base of the hypopharynx and opening into a large, stiff-walled, bulblike structure (Fig. I7O A, Pmp) [ 3 ] INSECTS which is the mouth cavity. The anterior wall of the bulb is ordinarily collapsed, but it can be lifted by a set ofstrong muscles (Mcl) arising on the front wall of the head (Clp). This bulb is the sucking pump of the fly, and it will be B C D FIO. 17o. Mouth parts of a horsefly, Tabanus atratus A, the labrum (Lin) and mouth pump (Prnp), with dilator muscles of the pump (1tcl) arising on the clypeal plate (CIp) of the head wall. The mouth is behind the base of the labrum B, the left mandible C, the left maxilla, consisting of a long piercing blade (Lc), and a large palpus (PIp) D, the labium (Lb) terminating in the large labdla (La), and the hypopharynx (Hphy) showing the salivary duct (SID) and its syrine (8.vr), discharging into a channd of the hypopharynx (Hphy) that opens at the tip of the latter seen that it is very similar to that of the cicada (Fig.  22, Pmp). In the fly, however, the liquid food is drawn up to the mouth through the labro-hypopharyngeal tube instead of through a channel between the appressed maxillae. The mandibles of the horsefly (Fig. 7 o B, Md) are long, bladelike appendages, very sharp pointed, thickened on [ 3aa ] MOS.QUITOES AND FLIES the outer edges and thin on the knifelike inner edges. They appear to be cutting organs, for each is articulated to the lower rira of the head bv its expanded base in such a manner that it can swing sidewise a little but can not be protruded and retracted as can the corresponding organ of the cicada. The maxillae (C) are slender stylets, each supported on a basal plate attached to the head; this plate carries also the large, two-segmented palpus (Plp). The maxillae are probably the principal piercing tools of the horsefly's mouth-part equipment. The median hypopharynx (Fig. 7 o D, Hphy) is a tapering blade somewhat hollowed above, normally ap- pressed, as just observed, against the under surface of the labrum to form the floor of the food canal. The hypo- pharynx itself is traversed by a narrow tube which is a continuation from the salivarv duct (SID). The latter, however, just before it enters t}e base of the hypopharynx, is enlarged to form an injection syringe (Svr). The salivary syringe in structure is a small replica of the mouth pump (A, Pmp), and its muscles arise on the back of the latter. The salira of the fiy is injected into the wound from the tip of the hypopharynx. By reason of this fact, the bite of a fly may be the source of infection to the victim, for it is evident that the injection of salira affords a means for the transfer of internal disease parasites from one animal to another. Behind ail the parts thus far described is the median labium (Fig. 7 o D, Lb), a much larger organ than any of the others, consisting of a thick basal stalk and two great terminal lobes (La). The sort, membranous under sur- faces of the lobes, which are known as the labella, are marked by the dark lines of many parallel, thick-walled grooves extending crosswise. These grooves may be channels for collecting the blood that exudes from the wound, or they may also distribute the salira as it issues from the tip of the hypopharynx between the ends of the labella. The effect of the salira of the horsefly on the INSECTS blood is not known, but the saliva of some files is said to prevent coagulation of the blood. Some of the smaller horseflies will give us an unsolicited sample of their biting powers, and in shaded places along roads they often make themselves most vexatious to the foot traveler just when he would like to sit down and enjoy a quiet test. To horses, cattle, and wild mammals, how- ever, these files are extremely annoying pests, and, where abundant, they must make the lives of animais almost unendurable; for the sole means of protection the latter bave against the painful bites of the flies is a swish of the tail, which only drives the insects to make a fresh attack on some other spot. There is another familv of "biting" flies, known as the robber flies, or Asilidae (]Tig. 167) , the members of which attack other insects. They are strong flyers and take their victims on the wing, even bees falling prey to them. The robber flies bave no mandibles, and the strong, sharp- pointed hypopharynx appears to be the chief piercing implement. The saliva of the tir injected into the wound dissolves the muscles of the victim, and the predigested solution is then completely sucked out. As was shown in Çhapter VIII, on metamorphosis, • whenever the adult form of an insect is highly specialized for a particular kind of lire, it is usually round that the young is also specialized but in a way of its own to adapt it to a manner of living quite different from that of its parent. This principle is particularly true of the flies, for, if the adult flies are to be regarded as in general the most highly evolved in structure of ail the adult insects, there can be no doubt that the young fly is the most highly specialized of ail the insect larvae. The files belong to that large group of insects which do hot bave external wings in the larval stage, but with the flies the suppression of the body appendages includes also the legs, so that their larvae are hot only wingless but legless as well (Fig. 7I). The legs, however, as the wings, , IOS.QL ITOES AND FLIES are represented by internal buds, which, when they enter the period of growth during the early stage of metamor- phosis, are turned inside out to form the legs of the adult tir. The lack of legs gives a cylindrical simplicity of form to most fly larvae, which hot onlv makes these insects look lik, e worms, but bas caused manv of them to lire the lire of / ml LTpa An Fro. 171. Structure of a fly larva, or maggot anus; .ISp, anterior spiracle; DTra, dorsal tracheal trunk; LTra, lateral tracheal trunks; mb, mouth hooks; PSp, posterior spiracle a worm and to adopt the wavs of a worm. In compensa- tion for the loss of legs, the fli" larvae are provided with an intricate system of muscle fibers lying against the inner surface of the bodv wall, which enables them to stretch and contract and to make ail manner of contortionistic twists. At first thought it seems remarkable that a soh-bodied, wormlike creature can stretch itsel( by muscular contrac- tion. It must be remembered, however, that the body of the larva is filled with soif tissues, manv of which are but looselv anchored, and that the spaces between the organs are fil'led with a body liquid. The creature is, therefore, capable of pe.rforming movements bv making use of its structure as a hvdraulic mechanism; a contraction of the rear part o( the body, for example, drives the body liquid and the soit movable organs forward, and thus extends the anterior parts of the bodv. A contraction of the length- wise muscles then pulls up the rear parts, when the more- [325] INSECTS ment of extension may be repeated. In this fashion the soft, legless larva moves forward; or, by a reversal of the process when occasion demands, it goes backward. A special feature in the construction of fly larvae is the arrangement of their breathing apertures, which is cor- re!ated with the malmer of breathing. In most insects, as we bave learned (Fig. 70), there is a row of breath]ng pores, or spiracles, along each side of the body, which open into .3 -- , Fro. 7 ŒE, Rat-tailed maggots, larvae of the drone y» whkh lire submerged in water or mud and breathe t the surface through a long» tail-like respiratory tube Upper figure, resting beneath a small oating obiect; lower, feeding in mud at the ottom lateral tracheal trunks. In the tir larva, however, these spiracles are closed and are hot opened for respiration until the final change of the pupa to the adult. The tir larva is provided with one or two pairs of special breathing organs situated at the ends of the bodv. Some species have a pair of these organs at each end of te bodv (Fig. 171 , .J.ç, P«ç), and some a pair at the pos- terior end only. The anterior organs, when present (Fig. 171 , «J.ç), consist of perforated lobes on the first body segment, the pores of which communicate with the an- terior ends of a pair of large dorsal tracheal trunks (DTra). The posterior organs (PSp) consist of a pair of spiracles on the rear end of the body, which open into the posterior ends of the dorsal tracheae. By means of this respiratory arrangement, the tir larva can lire submerged in water, [3261 MOSQUITOES AND FLIES or buried in mud or any other sort medium, so long as it keeps one end of the body out for breathing. The rat-tailed maggot (Fig. I72), which is the larva of a large fly that looks like a drone bee, has taken a special advantage of its respiratory system; for the rear end of its body, bearing the posterior spiracles, is drawn out into a long, slender tube. The creature, which lives in foui water or in mud, can by this contrivance hide itself beneath a floating object and breathe through its tail, the tip of which may corne to the surface of the water at a point some distance away. The end of the tail is provided with a circlet of radiating hairs surrounding the spiracles, which keeps the tip of the tail afloat and prevents the water from entering the breathing apertures. The great disparity of structure between the larva of a tir and the adult necessarily involves much reconstruc- ti'on during the period of transformation, and probably the inner processes of metamorphosis are more intensive in the more highly specialized Diptera than in any other group of insects. The pupa of an insect, as we have seen in Chapter VIII (page 254), is verv evidently a preliminary stage of the adult, the larval characters being usually discarded with the last molt ofthe larva. The pupa ofmost files, however, while it has the general structure of the adult fly (Fig. 82 A, F), retains the special respiratory scheme of the larva and at least a part of the larval breathing organs. The fact that the larvae breathe through special spiracles located on the back suggests that the primitive fly larvae lived in water or in sort mud, and that it was through an adaptation to such an environment that the lateral spiracles were closed and the special dorsal spiracles de- veloped. The retention by many fly pupae of the larval method of breathing and of at least a part of the larval respiratory organs, though their habitat would hot seem necessarily to demand it, suggests, furthermore, that the [3OE7 ] INSECTS pupae of the ancestors of such species lived in the saine medium as the larvae.. Ifour supposition is correct, we may see a reason tor the apparent exception in the files to the general rule that the pupa presents the adult structure and discards the pecu- liarly larval characters. The pupae of some flies whose Fro. 73- Larva (A) and pupa (B) ofa horsefly, Tabanus puncti- fer (about 1  rimes natural size) /n, anus; H, head; PSp, posterior spiracle; Sp, spiracle larvae lire in the water, however, revert at once to the adult system of lateral spiracles (Fig. 73 B, Sp). With such species, the larva cornes out of the water just belote pupauon time and transforms in some place where breathing is possible by the ordinary respiratory organs. This is the general fuie with other insects whose larvae are aquatic. The order of the Diptera is a large one, and we might go on indefinitely describing interesting things about flies m general. Such a course, however, would soon fill a larger book than this; hence, since we are already in the last chapter, a more practical plan will be to select for special consideration a few species that have become closely as- sociated with the welfare of man or of his domesticated animais. Such species include the mosquitoes, the bouse fly, the blowfly, the stable fly, the tsetse fly, the flesh files, and related forms. [ 3-8 ] MOS(2UITOES AND FLIES ,OSQUITOES The mosquitoes, perhaps more than any other noxious insect, impel us to ask the impertinent question, why pests were ruade to annoy us. It would be well enough to answer that they were g:lven as a test of the efficiency of our science in learning how to control them, if it were not for the other creatures, the wild animais, whose existence must be at times a continual torment from the bites of insects and from the diseases transmitted by them. Such creatures must endure their tortures without hope of relief, and there is ample evidence of the sufl'ering that insects cause them. In earlier and more primitive days the rainwater barrel and the town watering trough took the place of the course in nature studv in our present-day schools. While the lessons of the water barrel and the trough were perhaps hot exact or thoroughly scientific, we at least got our learning from them at first hand. We ail knew then what "wigglers" and "horsehair snakes" were; and we knew that the former turned into mosquitoes as surelv as we believed that the latter came from horsehairs. \lodern nature study has set us upon the road to more exact science, but the aquarium can never hold the mysteries of the old horse trough or the marvels of the raJnwater barrel. The supposed ancestry of the horsehair shake is now an exploded myth, but the advance of science has unfortu- nately hot altered the fact that wigglers turn into mos- quitoes, except in so far as the spread of applied sanita- tion has brought it about that fewer of them than for- merly succeed in doing so. And now, as we leave the homely objects of our first acquaintance with "wigglers" for the more convenient apparatus of the laboratory, we will call the creatures mosqu#o larvae, since that is what thev are. OEhe rainwater barrel never told us how those wiggling [39 ] INSECTS mosquito larvae got into it--that was the charm of the barrel; we could believe that we stood face to face with the great mystery of the origin of lire. Now, of course, we understand that it is a very simple matter for a female FIO. I74. Lire stages of a mosquito, Culex quinquefasciatus A, the adult female. B, head of an adult maie. C, a floating egg fart, with four eggs shown separately and more enlarged. D, a young larva suspended at the surface of the water. E, full-grown larva. F, the pupa resting against the surface film of the water [ 33 ° 1 MOSQUITOES AND FLIES mosquito to lay her eggs upon the surface of the water, and that the larvae corne from the eggs. There are many species of mosquitoes, but, from the .standpoint of human interest, most of them are included in three groups. First there are the "ordinary" mos- quitoes, species of the genus Culex or of related genera; second, the yellow-fever mosquito, dëdes aegypti; and third, the malaria-carrying mosquitoes, which belong to the genus dnopheles. The common Culex mosquitoes (Fig. I74 A) lay .their eggs in small, fiat masses (C) that float on the surface of the water. Each egg stands on end and is stuck close to its neighbors in such a manner that the entire egg mass has the form of a miniature raft. Sometimes the eggs toward the margin of the raft stand a little higher, giving the mass a hollowed surface that perhaps decreases the chance of accidental submergence, though the raft is buoved up from below by a film of air beneath the eggs. A]most any body of quiet water is acceptable to the Culex mosquito as a receptacle for her eggs, whether it be a natural pond, a pool of rainwater, or vater standing in a barrel, a bucket, or a neglected tin can. Each egg raft contains two or three hundred eggs and sometimes more, but the largest raft seldom exceeds a fourth of an inch in longest diameter. The eggs hatch in a very short time, usually in less than twenty-four hours, though the in- cubation period may be prolonged in cool weather. The young mosquito larvae corne out of the lower ends of the eggs, and at once begin an active lire in the water. The body of the young mosquito larva is slender and the head proportionately large (Fig. 174 D). As the creature becomes older, however, the thoracic region of the bodv swells out until it becomes as large as the head, or finallv a little larger (E). The head bears a pair of lateral eyes iFig. 175, b), a pair of short antennae (dnt), and, on the ventral surface in front of the mouth, a pair of large brushes of hairs curved inward (a). From the sides of [331 ] INSECTS the bodv segments project laterally groups of long hairs, some of which are branched in certain species. The rear end of the bodv appears to be forked, being divided into an upper and a ]ower branch. The Fm. 7- Structure of a Culex mosquito larva a, mouth brushes; abdomen; Ant, antenna; b» eye; c, respiratory tube; d, terminal lobes; H, head; " P8p, posterior spiracle; TA, thorax; Tra, dorsa tracheal trunks upper branch (c), however, is reallv a long tube projecting dor- sallv and backward from the next to he last segment. The lower branch is the true terminal seg- ment of the body and bears the anal opening of the alimentary canal at its extremitv. On the end of this segment ur long, trans- parent flaps project laterally (d), tso groups of long hairs are situ- ated dorsally, and a fan of hairs ventrallv (.Fig. 174 E. The principal characteristic of the mosquito larva is the speciali- zation of its respiratory system. The larva breathes through a single large aperture situated on the end of the dorsal tube that projects from the next to the last segment of the bodv (Fig. 175, PSp). This orifice opens by two mner spiracles into two wide tracheal trunks (Tra) that extend forward in the bodv and give off branches to ail the internal organs. The mosquito larva, therefore, can breathe only when the tip of its respiratory tube projects above the surface of the water, and, though an aquatic creature, it can be drowned by long submergence. Yet the provision for breathing at the surface has a distinct advantage: it renders the mosquito larva independent of the aeration of the water it inhabits, and allows a large number of larvae to thrive [33 OE ] MOSQUITOES AND FLIES in a small quantity of water, provided the latter contains suFficient food material. The tip of the respiratory tube is furnished with rive small lobes arranged like the points of a star about the central breathing hole. When the larva is below the sur- face, the points close over the aperture and prevent the ingress of water into the tracheae; but as soon as the tip of the tube cornes above the surface, its points spread apart. Not only is the breathing aperture thus exposed, but the larva is enabled to remain indefinitelv suspended from the surface film (Figs. 74 D, 18 B). l'n this posi- tion, with its head hanging downward, it feeds from a current of ater swept toward its mouth by the vibration of the mouth brushes. Particles suspended in the water are caught on the brushes and then taken into the mouth. Anv kind of organic matter among these particles con- stitutes the food of the larva, l.arvae of Çulex mos- quitoes, however, feed also at the bottom of the water, where fi»od material mav be more abundant. The bodv of the mosquito larva has apparently about the saine d'ensitv as water; when inactive below the sur- face, some larvae slowlv sink, and others rise. But the mosquito larva is an energetic swimmer and can project itself in any direction through the water bv snapping the rear halfof its bodv from side to side, whicl characteristic performance has given it the popular naine of "'wiggler." The larva can also propel itself through the water with considerable speed without any motion of the bodv. This movement is produced by the action of the mouth )rushes. l.ikewise, while hanging at the top of the water, the larva can in the saine manner switag itself about on its point of suspension, or glide rapidly across the surface. The larvae of Culex mosquitoes reach maturity in about a week after hatching, during the middle of summer; but the larval period is prolonged during the cooler seasons of spring and fall. The larva passes through three stages, and then becomes a pupa. [333 ] INSECTS The mosquito pupa (Fig. 74 F) also lives in the water, but is quite a different looking creature from the larva. The thorax, the head, the head appendages, the legs, and the wings are ail compressed into a large oval mass from A Mx f Hphy Lb B F¢.  76. Mouth parts of a female mosquito, ïoblotia digitat,, A, the head with the proboscis (Prk) in natural position. B, the mouth parts separated, showing the component pieces of the proboscis .4rit, antenna; E, compound eye; Hphy, hypopharynx; Lk, labium; Lin, labrurn; Md, mandibles; Mx, maxillae; MxPlp, Plp, max- illary palpi; Prk, proboscis which the slender abdomen hangs downward. The pupa, owing to air sacs in the thorax, is lighter than water and, when quiet, it rises to the surface where it floats with the back of the thorax against the surface film. The pupa has lost the respiratory tube and the posterior spiracles of the larva, but has acquired two large, trumpetlike breathing tubes of its own that arise from the anterior part of the [ 334 ] MOSQUITOES AND FLIES thorax, the rnouths of which open above the water when the pupa cornes in contact with the surface. The pupa, of course, does hot feed, but it is alrnost as active as the larva, for it rnust avoid its enemies. When disturbed it rapidly swirns downward by quick rnovernents of the abdomen, the extrernity of which is provided with two large swirn- rning flaps. The duration of the pupal stage in midsurnrner is about two days. The adult rnosquito issues flore the pupal skin through a split in the back of the latter. We now see whv the pupa is made lighter than water--it must float at the surface in order to allow the adult to escape into the air. The full-fledged mosquito (Fig. 74 A) bas the general fea- tures of anv other two-winged fly, but it s distinguished from nearly all other flies by the presence of scales on its wings and on parts of its head, body, and ap- pendages. The rnouth parts of the adult / \ / \_ / \ Fc. 177. lëdes atropalpus, maie, a mosquito re- lated to the yellow lever mosquito and similar to it in appearance m.osq.uito are of the plerclng and sucking type, and are sirnilar in structure to those of the horsefly, except that the individual pieces are longer and slenderer, and together constitute a beak, or proboscis, extending forward and downward frorn the head (Fig. I76 A, Prb). The rnale and the fernale rnos- quitoes are readily distinguishable by the character of the antennae, these organs in the rnale being large and feathery (Fig. 74 B), while those of the female are [335 ] " INSECTS threadlike and provided with comparatively few short hairs (A). The sexes differ also in the mouth parts, for, as in the horseflies, the males lack mandibles. The mouth parts of the mosquito, in the natural posi- tion, do hot appear as separate pieces, as do those of the horseflv. The various elements, except the palpi, are com- pressed into a beak that projects forward and downward from the lower part of the head (Fig. 176 A, Prb). "l'he length of the beak varies in different kinds of mosquitoes; it is particularly long in the large South American species shown in Figure 76. When the beak of the female mosquito is dissected (Fig. 76 B), the saine equipment of parts is revealed as is possessed bv the female horseflv IFig. 69 B), namely, a [abrum (Lin), two mandibles (.(ld), two maxil[ae (.1Ix), a hypopharynx (Hph.v), and a labium (Lb). It is the labium that forms most of the visible part of the beak, the other pieces being concealed within a deep gro«ve in its upper surface. The la/rivera (Fig. 176 B, Lin) is a long median blade, concave below, terminating in a hard, sharp point; it is probably the principal piercing tool of the mosquito's outfit. The mamtib/es of the mosquito (:lld) are verv slender, delicate bristles; those of the species figured are so weak that it would seem thev can be oflittle use to the insect. The maxi//ae (Mx) are thin, fiat organs with thickened bases, each terminating in a sharp point armed on its outer edge with a row of backward-pointing, saw- like teeth which probabl.v serve to keep the mouth parts fixed in the puncture as the perclng lalrum is thrust deeper into the flesh. "Fhe pa/pi I.IlxP/p) arise from the bases of the maxillae. The h)'popha?mx (lqpk),) is a slender blade with a median rib which is traversed bv the channel of the salivarv duct. ts upper surface is con- cave and, in the naturai position, is closed against the concave lower side of the labrum, the two apposed pieces thus forming between them a tube which leads up to the [ 336 ] blOS(UITOES AND FLIES mouth opening. The saliva of the mosquito is injected into the wound from the tip of the hypopharynx, and the blood of the victim is sucked up to the mouth through the labro-hypopharyngeal tube. The labium (Lb} serres F,c. 178. Mosquito larvae A, Atë'des atropalpus. 13, .¢nopheles punctipennis, the malaria mosquito larva c, respiratory tube; d, terminal Iobes; e, stellate groups of hairs that hold the larva at the surface of the water (fig. 181 A); f, spiracular area; P8p, spiracle principally as a sheath for the other organs. It ends in two small lateral lobes, the labella, between which pro- ]ects a weak, median tonguelike process. When the mos- quito pierces its victim the base of the labium bends back- ward as the other bristlelike members of the group of mouth parts sink into the wound. blosquitoes of both sexes are said to feed on the sap of [ 337 ] INSECTS plants, which they extract by puncturing the plant tissues; they will also feed on the exuding juices of fruit, or on any sort vegetable matter. The females, however, are notori- ous for their propensity for animal blood, and they by no means limit their quest for this article of food to human beings. The maie mosquitoes, apparently, very rarely depart from a vegetarian diet. The pain from the bite of a female mosqmto and the subsequent irritation and swelling probbly result from the injection of the secre- tion from the salivary glands of the insect into the wound. It is said that the salira of the mosquito prevents coagula- tion of the blood. Because of the short time necessary for the completion of the lire cycle from egg to adult during summer, there are manv generations of mosquitoes from spring to fall. The winer is passed both in the adult and in the larval stage. Fertile females mav survive cold weather in pro- tected places; and larvae round in large numbers, frozen solid in the ice of ponds, have become active on being thawed out, and capable of development when given a sufficient degree o warmth. The vellow-fever mosquito, now known as .lë'des aeg.vpti but at the rime of the discovery of its relation to yellow lever generally called ,çt«gom),ia.[asdata, is similar in its habits during the larval and pupal stages to the Culex mosquitoes. It lavs its eggs singly, however, and they float unattached on the surface of the water. The adult mosquito mav be identified by its decorative markings. On the back of the thorax is a lyrelike design in white on a black ground; the joints of the legs are ringedwith white the black abdomen is conspicuously cross-banded with white on the basal half of each segment. The maie has arge plumose antennae and ong maxillary palpi. The female has a strong beak, but small palpi, and her an- tennae are of the short-haired form usual with female mosquitoes. The species of .iëdes shown in Figure 177 much resembles the vellow-fever mosquito, but it is a [338] MOS.QUITOES AND FLIES more northern one common about Washington, D. C., where it breeds in rock pools along the Potomac River. The larva of Aëdes (Fig. 78 A) resembles a Culex larva, but it feeds more habitually at the bottom of the water and may spend long periods below without coming to the Fro. 179. Mosquito pupae in natural position resting against the under surface of the water A, .4ëdes atropalpus. B, .4nopheles punctipennis surface for air. In its search for food it noses about m the refuse at the bottom of the water and voraciously con- sumes dead insects and small crustaceans. The pupa like- wise (Fig. I79 A) does hOt differ materially from a Culex pupa. When quiet it floats at the surface of the water with the entire back of its thorax against the surface film and the tips of its breathing tubes above the surface. Probably no mosquito pupa hangs suspended from its resp.iratory tubes in the manner in which the pupae of vanous species are often figured. ./ëdes aegypti is the only known natural carrier of the virus of yellow lever from one person to another. The disease can be taken only from the bite of a mosquito of this species that has become infected by previous feeding on the blood of a yellow-fever patient. The organism that produces yellow fever is perhaps hOt yet definitely known, though strong evidence has been adduced to show [ 339 1 INSECTS that it is one of the minute, non-filterable organisms called spirochetes. The virus will hot develop m the mosquitoes at a temperature below 68 ° F., and ,tëdes aegypti will not breed /" in latitudes much be- "'\), ,,// yond the possible range of yellow lever. -,,/ Yellow fever, there- fore, is a disease ordi- narily confined to tbe • , tropics and warmer j/Ù.-\ parts of the te tope r- ate zones. Season- . al outbreaks of it that bave occurred in // \ northern cities bave been caused probably by local infestations // \ of infected mosqui- / / ] toes brought in on Fie.. 18o. The female malaria mosquito, ships from some .4nopheles punctipennis SOU thern port. The malaria mos- quitoes belong to the genus .tnopheles, a genus repre- sented by species in most temperate and tropical regions of the world, which are prevalent wherever malaria oc- curs. Our most common malaria species is «qnopheles punctipennis (Fig. 8o), characterized by a pair of dull white spots on the edges of the wings. The .tnopheles females lay their eggs singly on the surface of the water, where they float, each buoved up by an air jacket about its middle. The larvae of Anopheles (Fig. 78 B) differ conspicu- ouslv from those of Culex and Aëdes both in structure and habits. Instead of a respiratory tube projecting from nea the end of the body, as in Culex (Figs. 174 E 75), there is a concave disc (Fig. 78 B,f) on the back of the next to [ 34 ° ] MOSQUITOES AND FLIES the last segment, in which the posterior spiracles (PSp) are located. The larva floats in a horizontal position just below the surface film of the water (Fig. 18I A), from which it is suspended by a series of floats (,Fig. 178 B, e) consisting of starlike groups of short hairs arranged in pairs along the back. The spreading tips of the hairs pro- Fç. xSx. Feeding positions of.4n0pheles and Culex mosquito larvae A,/lnopheles larva suspended horizontally beneath the surface film, and feeding at the surface with its head inverted. B, Culex larva hanging from the respira- tory tube ject slightlv above the water surface and keep the larva afloat. In the floating position, the respiratory disc breaks through the surface film, and its raised edges leave a drv area surrounding the spiracles. The long hairs that projéct from the sides of the thorax and the first three bodv segments are mostly branched and plumose. T'he Anopheles larva (Fig. llqI A) feeds habitually at the top of the water. When disturbed it shoots rapidly across the surface in anv direction, but goes downward reluctantly. In order to feed in its horizontal position, it turns its head completely upside down and with its mouth brushes creates a surface current toward its mouth. The pupa of Anopheles (Fig. 179 B) is hot essentially [34 i ] INSECTS different from that of Culex or Aëdes. Its most distinc- tive character is in the shape of the respiratory tubes, which are verv broad at the ends. The parasitë of malaria is hot a bacterium but a micro- scopic protozoan animal named P/asmodium. There are several species or varieties that correspond with the difl'er- ent varieties of the disease. The malaria Plasmodium has a complicated life cycle and is able to complete its life only when it can spend a part of it in the body of a mosquito and the other part in some vertebrate animal. In the human bodv the malaria parasites lire in the red corpus- cles of the [lood. Here they multiply by asexual repro- duction, producing for a while manv other asexual gener- ations. Eventually, however, certain individuals are formed that, if taken into the stomach of an Anopheles mosquito, de»'elop there into males and females. In the stomach of the mosquito, these sexual individuals unite in pairs, and the resulting z, ygotes, as thev are called, penetrate into the cells of the stomach walf. Here thev lire for a while and multiply into a great number of sma[l spindle-shaped creatures, which go through the stomach wall into the bodv cavitv of the mosquito and at last col- lect in the salivary glam{s. If now the mosquito, with its salivary glands full of the Plasnodium parasites in this stage, bites some other animal, the parasites are almost sure to be injected into the wound with the salira. If thev are hot at once destroved by the white blood cor- pus'cles, thev will quickly enter the red blood corpuscles, and the victim will soon show symptoms of malaria. THE HOUSE FL." AND SOME OF lrs RELATIONS Our familiar domestic pest, the bouse fly, may be taken as the type of a large group of flies, and in particular of those belonging to the familv Muscidae, which is named from its best known member, 3luc domeIic, the bouse f]v--musc being the Latin word for fly. The bouse f]v (Fig. 82 A), though particularly a domes- [34  ] MOSOUITOES AND FLIE tic pest to people that live indoors, is intimatelv associated with the stable. Its favorite breeding place is the manure pile. Here the female flv lays her eggs (B), and here the larvae, or maggots (Ç), lve until they are readv for trans- formation. It is estimated that fullv ninety-five per cent of our house files bave been bred in horse manure. A few may corne from garbage cans, or from heaps of vegetable refuse, but such sources of fly infestation are comparatively unimportant. Measures of fly control are directed chiefly to preventing the access of files to stable manure and the destruction of maggots living in it. The eggs of the bouse flv IFig. 82 B) are small, white, .elongate-oval objects, about one twenty-fifth of an inch m length, each slightly curved on one side and concave on the other. The female tir begins to lay eggs in about ten days after having transformed to the adult form, and she deposits from 75 to 5o eggs at a single laying. She re- peats the laying, however, at intervals during her short productive period of about twenty days, and in ail may deposit over 2,ooo eggs. Each egg hatches in twenty-four hours or less. The larva of the house tly, in common with that of many other related files, is a particularly wormlike creature, and is commonly called a maggot IFig. 182 D). Its slender white body is segmented, but, in external appearance, it is legless and headless. On a fiat area at the rear end of the bodv are located two large spiracles (P,çp), which the novice might mistake for eyes. The tapering end of the body is the head end, but the true head of the maggot is withdrawn entirelv into the body. From the aperture where the head bas disappeared, which serves the maggot as a mouth, two clawlike hooks project (,h), and these hooks are both jaws and grasping organs to the maggot. The larva sheds its skin twice during the active part of its life, which is verv short, usually onlv two or three weeks. Then it crawls of to a secluded place, generally in the earth beneath its manure pile, where it enters a resting condi- [ 343 ] INSECTS tion. Its skin now hardens and contracts until the creature takes on the form of a small, hard-shelled, oral capsule, called a Dl@arium (Fig. 182 E). PSp F Fro. 182. The house fly, .lusca domestica A, the adult fly (5  rimes natural size). B, the house fly egg (greatly magnified). C, larvae, or maggots, in manure. D, a larva {.more enlarged). E, the puparium, or, hardened larval skin which becomes a case in which the larva changes to a pupa. F, the pupa [ 344 ] MOSQUITOES AND FI.IES Within the puparium, the larva sheds another skin, and then transforms to the pupa. The pupa (Fig. 82 F) is thus protected during its transformation to the adult by the puparial skin of the larva, which serres in place of a cocoon. When the adult is fully formed, it pushes off a circular cap from the anterior end of its case, and the fly emerges. The length of the entire cycle from egg to adult vanes according to temperature conditions, but it is usually from twelve to fourteen days. The adult flies are short-lived in sunanaer, thirty days, or not more than two months, being their usual span of life. In cooler weather, however, when their activities are suppressed, they lire ronger, and a few survive the winter in protected places. One of the essential differences between flies of the house tir type and the mosquitoes and horseflies is in the structure of the mouth parts. The house fly lacks mandi- bles and maxillae, but it retains the median members of the normal group of mouth-part pieces, which are the labrum, the hypopharynx, and the labium. These parts are combined to form a sucking proboscis that is ordi- narily folded beneath the head, but which is extended downward when in use (Fig. 183 A, Prb). The labium (Fig. 18.3 ], Lb) is the principal component of the proboscis of the house fly, and its terminal lobes, or labella (La), are particularly well developed. From the base of the labium there projects forward a pair of palps (Plp), which are probably the palpi of the maxillae, though those organs are otherwise lacking. The anterior surface of the labium is deeply concave, but its trough- like hollow is closed by the labrum (Lin). Against the labial wall çf the inclosed channel lies the hypopharynx (Hphy). When the lobes of the labium are spread out, the anterior cleft between them is closed except for a small central aperture (a). This opening becomes the func- tional mouth of the fly, though the true mouth is situated, as in other insects, between the bases of the labrum and the hypopharynx, and opens into a large sucking pump [ 345 ] INSECTS having the saine essential structure as that of the horse- fly (Fig. I7O A). The house fly has no piercing organs; it subsists en- tirely on a liquid diet. The food liquid enters the aper- ture between the labella, and is drawn up to the true t  P1p Lin_. La / B Flo. I8 3. Head and mouth parts of the house fly A, lateral view of the head with the proboscis (Prb) extended. /lnt, antenna; E, compound eye; La, labe[[a, terminal lobes of the pro- boscis; Plp. maxillary palpi (the maxillae are lacking); Prb, pro- boscis B, the proboscis of the fly, as seen in three-quarter front view and from below. The proboscis consists of the thick labium (Lb), ending in the labellar lobes (La), between which is a small pote (a) leading into the food canal (FC) of the proboscis. The food canal contains the hypopharynx (Hphy), and is closed in front by the labrum (Lin) mouth through the bod canal in the labium between the labrum and the hypopharynx. The fly, however, is hot dependent on natural liquids; it can dissolve soluble sub- stances, such as sugar, by means of its saliva. The saliva is ejected from the tip of the hypopharynx, and probably spreads over the food through the channels of the labial lobes. These saine channels, perhaps, also collect the food solution and convey it to the labellar aperture. [ 346 ] MOSQUITOES AND FLIES During recent years we have become so well educated concerning the ways of the bouse fly, its disgusting habits of promiscuous feeding, now in the garbage can or some- where worse, and next at our table or on the baby's face, and we bave learned so much about its menace as a pos- sible carrier of disease, that it is scarcely necessary to en- large here upon the flv's undesirability as a domestic companion. The most serious accusation against the bouse fly is that, owing to the many kinds of places it frequents with- out regard to sanitary conditions, and toits indiscriminate feeding habits, there is always a chance of its feet, body, mouth parts, and alimentary canal being contaminated with the germs of disease, particularly those of typhoid lever, tuberculosis, and dysentery. It bas been demon- strated that files can carry germs about with them which will grow when given a proper medium, and likewise that files taken at large may be covered with bacteria, a single fly sometimes being loaded with millions of them. The wisdom of sanitarv measures for the protection of food from contamination by files can not, therefore, be questioned. There is one form of insect villainy, however, of which the house fly is hot guilty; the structure of its mouth parts clears it of ail accusa- tions of biting. And yet we hear it often asserted by per- FIG. I8 4. Head of the stable fly, Stomoxys calcitrans .4nt, antenna; PIp, maxillary pal- pus; Prb, proboscis sons of unquestioned veracitv that they have been bitten bv bouse files. The case is one of mistaken identification and hot of imagination on the part of the plaintiff; the [ 347 ] INSECTS insect that inflicts the bite is not the house fly, but another species closelv resembling the common domestic fly in gen- eral appearance, though a little smaller. If the culprit is caught, there may be seen projecting from its head a long, hard, tapering beak (Fig. 84, Prb), an organ quite differ- ent from any part of the mouth equipment of the true house fly (Fig. 83). This biting fly is, in fact, the stable ff.v, a species known to entomologists as Stomoxvs calci- trans. It belongs to the saine family as the housefly, and while it sometimes cornes about houses, it is particularly a pest of horses and cattle. The stable fly lives in most parts of the inhabited world. Both sexes have blood-sucking habits, and probably feed on any kind of warm-blooded animal, though the species is most familiar as a frequenter of stables and as a pest of domestic stock. The stable fly breeds mostly in fer- menting vegetable matter, the larvae being found prin- cipally under piles of wet straw, hay, alfalfa, grain, weeds, or any vegetable refuse. Cattle are afflicted by another pestiferous fly called the horn fly, or Haematobia irritans. The species gets its common naine from the fact that it is usually observed about the bases o( the horns ofcattle, where great numbers of individuals often assemble. But the horns of the animais are merely convenient resting places. Haematobia is a biting fly like Stomoxys, and, because of its greater numbers, it often becomes a most serious pest of cattle. Through irritation and annoyance during feeding, it may cause loss of flesh in grazing stock, and a reduction of milk in dairy cows. The horn fly resembles the stable fly, but is smaller, being about one-half the size of the house fly. It breeds mostly in fresh manure of cattle dropped in the fields. Of ail the biting flies there is none to compare with the tsetse fly of Africa (Fig. 185). Not only is this fly an intolerable nuisance to men and animais because of the severity of its bite, but it is a deadly menace by reason of [ 348 ] MOS.QUITOES AND FI.IES its being the carrier of the parasite of Affican sleeping sickness of man, and that of the related disease called nagana in horses and cattle. African sleeping sickness is caused by a protozoan para- site of the genus Trypauosoma that lires in the blood and other body liquids. Trypanosomes are active, one-celled organisms having one end of the bodv prolonged into a tail, or flagellum. Thev are round as'parasites in many vertebrate animais, but most of them do not produce dis- ease conditions. There are at least three African species, however, whose presence in the blood of their hosts means almost certain death. Two cause the sleeping sickness in man, and the other produces nagana in horses, mules, and cattle. The two human species have different distribu- tions and produce each a distinct varietv of the disease. One is confined to the tropic.al parts of Africa, the other s more southern. The southern form of the disease is said to be much more severe than the tropical form, claiming its vic- tims in a marrer of months, while the other mav dra along for years. The sl'eepin sick- ness and nagana trypanosomes are entirelv dependent in nature on the tsetse files for their means of transport from one person or from one animal to another. The tsetse tir (Fig. Sç) is a FIG. 18 S. A tsetse fly, Glossina alals, maie (about rive times natural size) larger relation of the horn flv and the stable fly, having the saine type of beak and an insatiable appetite for blood. The tsetse fly genus is Glossina. There are two species particularly concerned with the transportation of sleeping sickness, corresponding with the two species of trypanosomes that cause the two [ 349 1 INSECTS forms of the disease. One is Glossina palpalis (Fig. 185) , distributor of the tropical varietv of the disease; the other is Glossina morsitans, carrier both of the southern variety of sleeping sickness and of nagana. The stable fly, the horn fly, and the tsetse fly, we bave said, belong to the saine family as the bouse fly, namely, the Muscidae; and yet they appear to bave mouth parts of a very different type. The differences, however, are of a superficial nature. All the muscid flies, biting and non- biting, have the saine mouth-part pieces, which are the labrum (Figs. I83 B, I86 C, Lin), the hypopharynx (Hphy), and the labium (Lb). They lack mandibles and maxillae, though the maxillary palps (P/p) are retained. In the biting species, the labium is drawn out into a long, slender rod (Fig. I86 C, Lb), and its terminal lobes, the labella (La), are reduced to a pair of small, sharp-edged plates armed on their inner surfaces with teeth and ridges. In the natural position, the deflected edges of the labrum (Fig. I86 B, Lin) are held securely within the hollow of the upper surface of the labium (Lb), the two parts thus in- closing between them a large food canal (FC) at the bot- tom of which lies the slender hypopharynx (Hphy), con- taining the exit tube of the salivary duct. The biting muscids, therefore, have a strong, rigid, beaklike proboscis formed of the saine pieces that com- pose the sucking proboscis of the house fly (compare Fig. 83 A with Figs. I84 and I86 A), but the labium is so modified that it becomes an effective piercing organ. When one of these files bites, it sinks the entire beak into the flesh of its victims. The tsetse fly is said to spread its front legs apart when it alights for the purpose of feeding, and to insert its beak by several quick downward thrusts of the head and thorax. The insect then quickly fills itself with blood, with which it may become so distended that it can scarcely fly. The bulb at the base of the tsetse fly's labium (Fig. 86 C, b) is no part of the sucking apparatus; it is merely an enlargement for the accommodation of [ 35o ] MOSQUITOES AND FLIES muscles. The true sucking organ lies within the head (Pmi)) , and does hot differ in structure from that of other files. While our indictment of the files has applied thus far only to the insects in the mature form, there are species which, though entirely innocent of any criminality in their L1Tl  "-Lb C  Fc. 86. ttead and muth parts f the tsetse fly, Çloia , lateral iew f the head and wobsds (Pr) f Çloia alpali, maie B» cross-section f the wobseis f Çloia]ea (fmm Vgel), shwing the food canal (FC) indd by the labrum (L) and labium (), and entaining the tubular hypharynx (Hy) through whieh the salira is ineeted inm the wund Ç, muth parts fÇlosia alpali with the rts f the probseis separated.  basal swdling f the labium; , the labella, r terminal lb f the labium us fr «utting inm the skin f the ietim; , labium; m, labrum; Pl, maillary palpus (the maxillae are la«king) P, muth pump [35 ] INSECTS adult behavior, are, however, most obnoxious creatures during their larval stages. The ordinary blowflies, which are related to the bouse fly, lay their eggs in the bodies of dead animais, where the larvae speedily hatch and feed on the putrefying flesh. Another kind of blowfly deposits living larvae instead of eggs. These flies may be regarded as beneficial in that their larvae are scavengers. But some of their relations appear to bave taken a diabolical hint from their habits, for they make a practice of depositing their eggs in open wounds, sores, or in the nostrils of living animais, including man. Tbe larvae burrow into the tis- sues of the victims and cause extreme annoyance, surfer- ing, and even death. A notable species of this class of pests is the screw worm. Infestation by fly larvae, or maggots, is called myiasis. Well-known cases of animal myiasis are tbat of the bot- fly in horses and of the ox warble in cattle. The files of both these species lay tbeir eggs on the outside of the animais. The young larvae of the botfly are licked off and swallowed, and then lire until full-grown in the stomach of the host. The young ox-warble larva burrows into the flesh of its host and lires in the body tissues until mature, when it bores through the skin on the back of the aflqicted beast, drops out, and completes its transforma- tion in the ground. Not only animais but plants as well are subject to m- ternal parasitism by fly larvae. Garden crops are at- tacked by leaf maggots and root maggots; orchardists in the northern States bave to contend against the apple maggot, which is a relation of the olive fly of southern Europe and of the destructive fruit files of tropical coun- tries. That notorious scourge of wheat fields, the Hessian fly, is a second or third cousin of the mosquito, and itis in its larva form that it makes all the trouble. The special attention that bas been given to pestiferous files must make it appear that the Diptera are a most undesirable order of insects. As a matter of fact, however, [35"-1 MOSQUITOES AND FLIES there are thousands of species of flies that do not affect us in any injurious way; while, furthermore, there are species, and many of them, that render us a positive serv- ice by the fact that their larvae lire as parasites in the bodies of other injurious insects and bring about the de- struction of large numbers of the latter. Scientifically, the Diptera are most interesting insects, because they illustrate more abundantly than do the members of any other order the steps by which nature has achieved evolution in animal forms. An entomologist would sav that the Diptera are highly specialized insects; and as evidence of this statement he would point out that the files have developed the mechanical possibilities of the common insect mechanism to the highest general level of eflqciency attained by any insect and that they have carried out many lines of special modification, giving a great variety of new uses for structures originally limited to one mode of action. But when we say that any animal has developed to this or that point of perfection, we do hOt mean just what we say, for the creature itself has been the passive subject of influences working upon it or within it. A fundamental study of biology in the future will consist of an attempt to discover the forces that bring about evolution in living things. [ 353 ] INDEX A Acrididae, OE8 dë'des, adult, 338 larva, 339 pupa, 339 dëdes aegypti, 33 , 339, 34o carrier of yellow lever, 339 Aesop and the cicada, 83 Agile meadow grasshopper, 53 Alimentary canal, c) /Imblycorypha oblongifolia, 39 habits, 40 song, 41 me collective, 43 American cockroach, 79 /Inabrus simplex, _ 4 Ancient insects, 77 Angular-winged katydids, 4-43 Annual cicadas, 84 song, 184 /lnopheles, 331, 34 ° punctipennis, sec Malaria mos- quitoes Antennae, 12 Aphids, ISOE apple, 57, 6 birth, 164 cornicles, 174 eggs, 57 feeding, garden, I7L 172 hatching, I59-16 mouth parts, 153 parasites, 78 predators, stem mothers, 162 wing production, 164-166 young, 162 Aphis, 153 apple-grain, 7 o green apple, rosy apple, Aphis-lion, 176 Arthropoda, OE6 Asilidae, 3OE4 Australian cockroach, 79 B Beetles, blister, lady, 75, OE3 o May, OE3 o young, 237 Behavior, 10E6 Black cricket, 60 in New England, 60 rivalry of males, 62 song, 60-63 Black-horned tree cricket, 67 antennal marks, 67 attraction of female by maie, 68, 69 song, 68 Blatella germanica, sec German roach Blood of insects,  OE Blowflies, 352 Botflies, 35OE Brain, liT, II8 Broad-winged tree cricket, 65 antennal marks, 67 song, 64 Bush crickets, 69 song, 7 ° Bush katydids, 38 song, 39 [ 355 1 INDEX C Camel crickets, 55 Cantharidin, OE3 Carboniferous dragonflies, 95 insects, 86, 89, 9 ° plants, 87, 88 Caterpillar, OE6OE alimentary canal, OE89, OE9 o celery, OEOE9 jaws, 86 life, OE6OE nature, OEOE8 silk glands, OE87 press, OE88 spinneret, OE86 spinning of cocoon, OESOE, OE83 structure, OE37 tent, transformation to moth,oE93-3o5 Caterpillar and moth, OE6OE Cecropia moth, OEOES, OEOE9 Cellulose, digestion of, by ter- mites, 137 Chitin OE56 Chloealtis conspersa, 3 ° musical apparatus, 3 ° song, 3 o, 3 I Chrysalides, OE51 Cicadas, annual, 184 periodical, 184--OEOE 5 Cicadidae, Circotettix carlingianus, 3OE verruc ulatu s , Cockroaches, 79 Collembola, OE47 Common meadow grasshopper, 5OE song, 53 Coneheads, 50 Conocephalus fasciatus, 54 song, 54 Corn-root aphis, Coulee cricket, 54 Cricket family, 55 Crickets, 55 bush, 69 camel, 55 European, 55 field, 58 foot, 55 mole, 58 musical organs, 56, 57 tree, 63 Croton bug, see German roach Culex, 33 I eggs, 33 I food, 337, 338 larva, 33  maie and female, 335 mouth parts, 335-337 D Deer flies, 3oEo Diapheromera Jemorata, 7  Digestion,  IO Diptera, 315 Double soma, 3o4 Dragonflies, 95 adult, OE33 Carboniferous, 95 young, OE33 E Ears of grasshoppers, 3 ° of katydids, 36 Egg laying of cicada, OEIOE Eggs of aphids, 157 , I58 of cicada, OEIOE Culex mosquito, 33 I grasshopper, 5, 6, 7 bouse fly, 343 roaches, 8o, 8 I tent caterpillar, OE6OE Enzymes, i I i Epicauta vittata, OEOE European house cricket, 55 [ 356 ] INDEX F Fat-body, OE6o, OE9 OE Field crickets, 58 Flies, 314 horn fly, 348 horsefly, 32o--3oE4 house fly, 34oE-347 in general, 315 larva, 325 pupa, 3oE7 stable fly, 348, tsetse fly, 348 young, OE3 l Food exchange by termites, 144 Foot of cricket, 55 of grasshopper, 3 katydid, 3 OE Fork-tailed bush katydid, 39 song, 39 Four-spotted tree cricket, 67 G Gadflies, 3oEo Ganglia, 118 Garden aphids, I7I , i72 Genus, defined, OE-v German roach, 79 egg case, 8 l hatching, 81, 8oE Germ cells, lOO, lO, 124, 304 Glossina, see Tsetse tir palpalis, 350 morsitans, 350 Grasshopper,  adults, 17 cousins, 26 definition, OE destruction of eggs by blister beetles, OE3, 24 devastation by, I8 ears, .30 egg laying, 4, 5 egg-pod, 5 eggs, 6, 7 Grasshopper, growth, 13, 14 hatching, 8, 9 head, 12 males and females, 3 migration, 18 molting, I4-I6 oviposttor, 4 parasite, I9, OEo songs, 3 o, 3 I spiracles, 13 wings, 29 young, I, 8, Il Grasshopper family, 28 Grasshopper's cousins, 26 Green apple aphis, 6OE-168 Green bugs, Gryllus, 58, 60 assimilis, see Black cricket domesticus, 55, 60 H Handsome meadow grasshopper, 54 song, 54 Halteres, 319 Heart, I 12 Hexapoda, see Insecta Histoblast, OE59 Histogenesis, OE6o Histolysis, 2_ç 9 Honey dew, 155 Hormones, I 19 Horsefly, 3oEo larva, 3oE5 mouth parts, 321-323 pupa, 3oE5 sucking pump, 3oE2 House centipede, 8oE, 83 House fly, 34oE breeding places, 343 eggs, 343 larva, 343 mode of feeding, 346 mouth parts, 345, 346 [ 357 ] House fly, pupa, 345 puparium, 344 unsanitary habits, 347 Hypermetamorphosis, OESo Hyperparasite, 18 [ Hypopharynx, 1o8 I lmaginal discs, 9-59 Imago, defined, 9-59 lnsecta, OE8 Intestine, 11o J Jumping bush cricket, 69 song, 7 ° June bugs, OE3 o K Katydid, 43 habits, 46 musical instruments, 47, 48 song, 44, 48, 49 true, 43 Katydid family, 32 Katydids, 32 angular-winged, 4' bush, 38 ears, 36 musical instrtnnents, 34-36 round-headed, 37 song, 33, 34 young, i 1 King termite, 134 L Labium, Io8 Labrum, Io8 Lady-beetles, 175, z3o Ladvbird beetles, [75, -3 ° Larva, characters, OE46 &finition, 9-45 nature, 9.49 of Aëdes, 339 Anopheles, 340, 341 INDEX Larva of Culex, 33 I, 339-, 333 of files, 39-5 house fly, 343 mosquitoes, 39-9 wasps and bees, 9-59- Leaf insect, 7 I, 79-, 73 Legs of insects, 1o 7 Lepisma, 93 Lire of a caterpillar, 9-69- Locustidae, 39- Locusts, 9- seventeen-year, 189- Luna moth, OEOES, 9-3 ° M .Iachilis, 93 Maggots, 9-59- ,4alacosoma americana, see Tent caterpillar Malaria mosquitoes, 34 ° adult, 340 eggs, 340 larva, 34 o, 341 pupa, 34 [ Malaria parasite, 342 Malpighian tubules, [[6 Mandibles, I+ 7 Mantids, 73 Mantis, praying, 73-76 eggs, 75, 76 Maxillae, 1o8 May beetles, 23o Mayfly, 96 Meadow grasshoppers, 59--54 Mecostethus gracili«, 3 [ Metabolism of pupa, Metamorphosis, [4, complete, 9-45 defined, OEOE7 diagram, 43 incomplete, of tent caterpillar, 9-97, 9-99-3o4 .lio-ocentrum retinerve, 41, 43 song, 43 [ 358 ] INDEX Microcentrum rhombifolium, 4x, 4 OE, 43 song, 41, 42, 43 Mde cricket, 58 song, 58 Molting of grasshopper, 4, I6 Mormon cricket, 54 Mosquitoes, 3oE9 adult, 33% 335, 338 .¢ë'des, 33 I /lnopheles, 33 I, 34o cornrnon, 33  Culex, 33 I larvae, 3oE9 rnalaria, 33 I, 34o Stegomyia, 338 yellow lever, 338 young, OE39 Moth of tent caterp]llar, 3o5 characters, 3o6, 3o7 egg laying, 3IoE ernergence frorn pupa, 3o5, 3o6 rnouth parts, 3o6, 3o7 proboscis, 3o7, 3o8 reproductive organs, 3   Moths, Cecropia, 2oE8 celery, OEoE9 Luna, OEoES, OE3 o Promethea, OEoE8 tent caterpillar, 3o5 Mouth parts, IoE, o 7 Musca domestica, see House fly Muscidae, 342 Musical instruments of cicada, of crickets, 56, 57 grasshoppers, 3% 3  msects, 33, 34 katydids, 34, 35, 36 Myiasis, 35oE N Nagana, 349 Narrow-winged tree cricket, 66, 67 Narrow-winged tree cricket, an- tennal rnarks, 66, 67 song, 67 Nemobius vittatus, 58 song, 58, 59 Neoconocephalus ensiger, 5o song, 5 retusus, 5o robustus, 5  song, 5 I Neocurtilla hexadactyla, 57 Neoxabia bipunctata, 69 Nervous systern,  17 Nyrnph, defined, 245 O Oecanthus angustipennis, see Nar- row-winged tree cricket latipennis, see Broad-winged tree cricket nigricornis, see Black-horned tree cricket nigricornis quadripunctatus, 68 niveus, see Snowy tree cricket Oesophagus, x o Orchelimum agile, . 3 laticauda, vuAgare, 5oE, 53 Oriental roach, 79, 8o Origin of insect wings, 9 , 9 OE Orocharis saltator, 7 o Ovaries, IOEOE Ovipositor, 4, IOE3 Ox warble, 352 P Paleodictyoptera, 9% 92 Parasites, defined, x79 of aphids, 77-79 grasshopper, 9, OEo Parthenogenesis, Periodical cicada, abdomen, OEo 5 adults, I99 [ 359 ] INDEX Periodical cicada, air chamber, 205 broods, 2rs-OEr 7 death of adults, 214 digging methods, 19o , 191 egg laying, 212-2 I4 eggs, 212, OEI 9 food, OE0O front leg of nymph, 19o hatching of eggs, head of aduh, 2oi huts, turrets, 192 mouth parts, OEoI-2O 5 musical instruments, 199 , OEo 7- nymphal chambers, I87-189 stages, 186, 187 nymphs, 185-i93 , ovipositor, 199 races, salivary pump, 204 song of large variety, 21o, OE! I of small variety, OEil, sucking mechanism, transformation, 193-199 two varieties, 99 young nymphs, 223-225 Phagocytes, 259 , Phaneroptera, 38 Pharynx, I o Phylloxera, I72 Phylum, OE6 Physiology of tent caterpillar, 283 Plant lice, 152 Plasmodium, 342 Proboscis of moth, 3o7, 3o8 Promethea moth, 228, 2°-9 Propupa of tent caterpillar, 296- OE98 Protoplasm, IOO Pterophylla camellifolia, see Katy- did Pupa, OE5 o, 253 , 54 added stage in metamorphosis, Pupa, definition, of flies, 3OE7 house fly, 345 mosquitoes, 334, 339, 34 I tent caterpillar, OE98 reason for, OE57 Puparium, of house fl, 344 Queen termite, 1.34, I49 R Rat-tailed maggot, 327 Reproduction, lO Reproductive organs, I2 Respiration, ! 14 Reticulitermes,  36 lire history, 136-I41 Rhadophorinae, 55 Roaches, 77, 8o and other ancient insects, 77 eggs, 8% 81 Robber flies, 324 Rocky Mountain locust, I7, 18, 19 Rosy apple aphis, I68-17o Round-headed katydids, 37 /lmblycorypha oblongifolia, 39 angular-winged, 4 fork-tailed bush, 39 Microcentrum, 4 I, 43 Phaneroptera, 38 Scudderia, 38, 39 S Sarcophaga kellyi,  9 2 I Scudderia, 38 fl«rcata, see Fork-tailed bush katydid Segments of body, 12 Sense organs, 121 [ 360 ] INDEX Seventeen-year locust, see Periodi- cal cicada Shield-bearers, 54 Sleeping sickness, 349 Slender meadow grasshopper, 54 Snowy tree cricket, 65 antennal marks, 66 musical instruments, 57 song, 66 Soldiers of termites, 3 Soma, o4, 304 Somatic cells, o 4 Song of insects, 33, 34 of cicada, 21o--212 crickets, 58, 60, grasshoppers, 3 katydids, 39, 41, 4 OE, 43, 44, 47, 48, 49, 5 , 53, 54 Spiracles, 3, I*4- Spirochetes, 34 ° Stagmomantis carolina, 73 Stimulus, o6 Stomach, Io 9 Stridulation, 33 Striped ground cricket, 58-6o song, 58, 59 Syrphid flies, 77 larvae feeding on aphids, ,76, '77 Sword-bearing conehead, 5o song, 51 T Tabanida, 320 Tent caterpillar, 26OE behavior on leafless tree, OE78, 279 cocoon, OE82 egg, OE63 egg mass, 263, 264 epidermis, OE95 fat-body, OEgoE feeding habits, 27% 27% OE73, .76 Tent caterpillar, general external form, OE85, OE86 head, OE84, OE85 internal organs, OE89-OE91 jaws, OE86 jumping from trees, OE8o, OES manner of feeding, OE77 metamorphosis, OE93 molts, OE75 moth, 305 newly-hatched, OE65 prepupal stage, OE95 propupa, OE96, OE97 pupa, OE98 silk glands, OE86 press, OE88 spinneret, OE86 spinning cocoon, OESOE, OE83 structure and physiology, OE83 tents, 270 weavlng tent, 272 , 273 young, 26OE in egg, 312, 313 Termites, 125 /Ïme collective, 43 castes, I31 , 14I , 142 community lire, 34 destruction by, OE9 digestion of cellulose, '37 egg laying,  50,  5  food exchange, 144 fungus grown for food, 48 king, 34 lire history, 36-4 I males and femmes, 33 nests aboveground, 48 in trees, 148 underground, 47 queen, 34, I49 Reticulitermes,  36 short-winged form, 33, I4° soldiers, 3 I tropical termites, 46 winged form, I33 [.361 ] INDEX Termites, wingless males and females, 14o workers, 131 young, I36 Testes, Tettigoniidae, 32 Thorax, 12 Thysanura, 24. 7 Tracheae, I 14 Tree crickets, 63 antennal marks, 66, 67 attraction of males for females, 68, 69 black-horned, 67 broad-winged, 65 four-spotted, 67 musical organs, 56, 57 narrow-winged, 67 Neoxabia, 69 Oecanttus, 65-68 snowy, 65 song, 65, 66, 67 two-spotted, 69 Triungulins, OE3 Tropisms, True katydid, 43 Trypanosoma, 349 Tsetse fly, 348, 349, 35 ° mouth parts, 350, 351 Two-spotted tree cricket, 69 song, 69 W Walking stick, 7 OE Walking stick insects, 7 I Wasps and bees, larvae, OE3o, OE38, Ways and means of living, 99 White ants, IOE8 White grubs, OE3 o Wings, 83, 84 evolution, 3  5 of bees, 319 beetles, 3  8 butterflies and moths, 3  8 dragonflies, 3  6 flies, 319 grasshoppers, 318 roaches, 83, 84, 3  8 termites, 146 , 36 wasps, 319 origin, 91, 9 OE Wigglers, OE3 o, 3OE9 Woolly aphis, 172 X Xiphidium, 54 Y Yellow lever, 339 Yellow fever mosquito, 331, 339, 34o [ 36OE ] 3 9088 00157823 6 nhent QL463.S6X Insects, the=r ways and means of living,