Introduction
TO
ENTOMOLOGY
BY
JOHN HENRY COMSTOCK
PROFESSOR OF ENTOMOLOGY AND GENERAL INVERTEBRATE ZOOLOGY, EMERITUS, IN CORNELL UNIVERSITY
SECOND EDITION, ENTIRELY REWRITTEN
ITHACA, N. Y.
THE COMSTOCK PUBLISHING CO.
COPYRIGHT 1920
BY
THE COMSTOCK PUBLISHING COMPANY
RE3S OF W. F. HUMPHRtY, GENEVA, N. Y.
TO
MY OLD STUDENTS
WHOSE YOUTHFUL ENTHUSIASM WAS A CONSTANT INSPIRATION DURING THE LONG PERIOD OF MY SERVICE AS A TEACHER THIS EFFORT TO CONTINUE TO AID THEM IS AFFECTIONATELY INSCRIBED
Preface To Part I
THE following pages constitute the first part of a text-book of entomology that the writer has in preparation. This first part is published in advance of the completion of the entire work in response to the request of some teachers who desire that it be available for the use of their classes.
The early publication of this part of the book will not only render it immediately available but will also afford an opportunity for the suggestion of desirable changes to be made before it is incorporated in the complete work. Such suggestions are earnestly invited by the writer.
In writing this text-book much use has been made of material published in my earlier works, notably in "An Introduction to Entomology" published in 1888 and long out of print, "A Manual for the Study of Insects," in the preparation of which I was aided by Mrs. Comstock, and in the "Wings of Insects," more recently published. The more important of the other sources from which material has been drawn are indicated in the text and in the bibliography at the end of the volume. References to the bibliography are made in the text by citing the name of the author and the year in which the paper quoted was published.
A serious obstacle to the popularization of Natural History is the technical names that it is necessary to use. In order to reduce this difficulty to a minimum the pronunciation of these names is indicated by indicating the length of the vowel that receives the primary accent.
The original figtires and the copies of published figures in the first chapter were drawn by Miss Anna C. Stryke; those in the three following chapters, by Miss Ellen Edmonson. I am deeply indebted to each of these artists for the painstaking care shown in her work.
Two objects are kept constantly in mind in the preparation of the text-book of which this volume is a part: first, to aid the student in laying a firm foundation for his entomological studies; and second, to make available, so far as possible in the limited space of a handbook, a knowledge of the varied phenomena of the insect world. It is hoped that those who use this book will find delight in acquiring a more intimate acquaintance with these phenomena.
John Henry Comstock. entomological laboratory cornell university
CHAPTER I Pages
The Characteristics of Insects and Their Near Relatives i
Phylum Arthropoda I
List of the classes of the Arthropoda 2
Table of the classes of the Arthropoda 3
Class Onychophora 4
Class Crustacea 6
Class Palseostracha 8
Class Arachnida 9
Class Pycnogonida 10
Class Tardigrada 12
Class Pentastomida • ^4
Class Diplopoda ^5
Class Pauropoda ^4
Class Chilopoda 28
Class Symphyla 23
Class Myrientomata 26
Class Hexapoda • • • ^o
CHAPTER II I. the structure of the body- wall
a. The three layers of the body-wall 29
The hypodermis ^9
The trichogens 3°
The cuticula 30
Chitm 30
Chitinized and non-chitinized cuticula 30
The epidermis and the dermis 3^
The basement membrane 3i
h. The external apophyses of the cuticula 3^
The cuticular nodules 31
The fixed hairs 31
The spines 32
c. The appendages of the cuticula 2>-
The spurs 3^
The setae 32
The taxonomic value of setae 33
A classification of setje 33
(i ) The clothing hairs 33
(2) The glandular hairs 33
(3) The sense-hairs 33
d. The segmentation of the body 34
The body-segments, somites or metamercs 34
The transverse conjunctivae 34
e. The segmentation of the appendages 34
/". The divisions of a body-segment 34
The tergum, the pleura, and the sternum 34
The lateral conjunctivae 35
The sclerites 35
The sutures 35
The median sutures 35
The piliferous tubercles of larvae 35
The homologizing of sclerites 35
g. The regions of the body 36
2. THE HEAD
The corneas of the eyes 36
The corneas of the compound eyes 36
The corneas of the ocelli 37
The areas of the surface of the head 37
The front 37
The clypeus 38
The labrum 38
The epicranium 38
The vertex 39
The occiput 39
The genae 39
The postgenas 39
The gula 39
The ocular sclerites 39
The antennal sclerites 39
The trochantin of the mandible 40
The maxillary pleurites 4^
The cervical sclerites 40
The appendages of the head 40
The antennae 4^
The mouth-parts 42
The labrum 42
The mandibles 42
The maxillalae 42
The maxillae 42
The labium or second maxilla; 45
XI d.
The epipharynx . g
The hypopharynx .-
The segments of the head .j
3. THE THORAX
The segments of the thorax! ^3
The prothorax, mesothorax, and metathorax 48
The aHtrunk , q
The propodeum or the median segment 40
The sclerites of a thoracic segment 40
The sclerites of a tcrgum 40
The notum .g
The postnotum or the postscutellum 50
The divisions of the notum cq
The patagia co
The parapsides cj
The sclerites of the pleura 51
The episternum ci
The epimerum gi
The preepistemum ci
The paraptera ci
The spiracles c2
The peritremes c2
The acetabula.
The sclerites of a sternum ^2
The articular sclerites of the appendages 53
The articular sclerites of the legs 53
The trochantin 53
The antecoxal piece 54
The second antecoxal piece 54
The articular sclerites of the wings 54
The tegula 54
The axillaries 54
The appendages of the thorax 55
The legs 56
The coxa 56
The styli 56
The trochanter 57
The femur 57
The tibia 57
The tarsus 57
The wings 58
The different types of wings 59
The margins of wings 60
The angles of wings 60
The axillary cord 60
The axillary membrane 60
The alula 60
The axillary excision 61
The posterior lobe 6i
The methods of uniting the two wings of each side 6i
The hamuH 6i
The frenulum and the frenulum hook 6i
The jugum 6i
The fibula 62
The hypothetical type of the primitive wing-venation 62
Longitudinal veins and cross- veins 64
The principal wing-veins 64
The chief branches of the wing- veins 64
The veins of the anal area 65
The reduction of the number of the wing- veins 65
Serial veins 67
The increase of the number of the wing-veins 68
The accessory veins 68
The intercalary veins 69
The adventitious veins 7^
The anastomosis of veins 7°
The named cross- veins 7 1
The arculus 7^
The terminology of the cells of the wing 72
The corrugations of the wings 73
Convex and concave veins 73
The furrows of the wing 73
The bullae 74
Tht ambient vein 74
The humeral veins 74
The pterostigma or stigma 74
The epiplurffi 74
The discal cell and the discal vein 74
The anal area and the preanal area of the wing 75
4. THE ABDOMEN 75
a. The segments of the abdomen 75
b. The appendages of the abdomen • 7^
The styli or vestigial legs of certain Thysanura 7^
The collophore of the Collembola 7^
The spring of the Collembola 7^
The genitalia 7°
The cerci 77
The median caudal filament 7^
The prolegs of larvae 7°
5. THE MUSIC AND THE MUSICAL ORGANS OF INSECTS 78
a. Sounds produced by striking objects outside of the body 79
h. The music of flight 80 xin c. Stridulating organs of the rasping type g j
The stridulating organs of the Acridiidse 82
The stridulating organs of the Gryllidas and the Locustid® 83
Rasping organs of other than orthopterous insects 87
d. The musical organs of a cicada 8q
e. The spiracular musical organs n j
/. The acute buzzing of flies and bees oi
g. Musical notation of the songs of insects 02
h. Insect choruses
CHAPTER III The Internal Anatomy of Insects I. the hypodermai, structures 95
a. The internal skeleton gc
Sources of the internal skeleton or
Chitinized tendons ne
Invaginations of the body- wall or apodemes 95
The tentorium gg
The posterior arms of the tentorium 96
The anterior arms of the tentorium 97
The dorsal arms of the tentorium 97
The frontal plate of the tentorium 97
The endothorax 07
The pragmas 97
The lateral apodemes 98
The furcse 98
b. The hypodermai glands 98
The molting-fluid glands 99
Glands connected with setae 99
Venomous setse and spines 100
Androconia 100
The specific scent-glands of females 100
Tenent hairs 100
The osmeteria 1 01
Glands opening on the surface of the body 1 02
Wax-glands 102
Froth-glands of spittle insects 1 02
Stink-glands 1 02
The cephalic silk-glands 1 03
The salivary glands 1 04
2. THE MUSCLES IO4
3. THE ALIMENTARY CANAL AND ITS APPENDAGES I07
a. The more general features 1 07
The principal divisions 108
Imperforate intestines in the larvae of certain insects 108 b. The fore-intestine 109
The layers of the fore-intestine 109
The intima ^^9
The epithelium 109
The basement membrane 109
The longitudinal muscles 109
The cirailar muscles 109
The peritoneal membrane 109
The regions of the fore-intestine 109
The pharynx ^09
The oesophagus ^ 10
The crop "^
The proventriculus ■ no
The oesophageal valve m
c. The mid-intestine ^^^
The layers of the mid-intestine m
The epithelium "2
The peritrophic membrane 112
d. The hind-intestine "2
The layers of the hind-intestine 112
The regions of the hind-intestine "3
The Malpighian vessels ^3
The Malpighian vessels as silk-glands 1 13
The caecum ^^^
The anus "^
4. THE RESPIRATORY SYSTEM '13
a. The open or holopneustic type of respiratory organs n 4
1. The spiracles i H
The position of the spiracles ^^4
The number of spiracles -^ ^4
Terms indicating the distribution of the spiracles 1 1 5
The structure of spiracles ^^
The closing apparatus of the tracheae i^o
2. The trachecB ^^
The structure of the tracheae "7
3. The tracheoles ^^
4. The air-sacs ^^
5 . Modifications of the open type of respiratory organs 119
b. The closed or apneustic type of respiratory organs 1 19
/. The Tracheal gills • • "9
2. Respiration of parasites 120
J. The blood-gills ^20
TABLE OF CONTENTS xv
5. THE CIRCULATORY SYSTEM 121
The general features of the circulatory system 121
The heart ^21
The pulsations of the heart 122
The aorta ''22
The circulation of the blood ^^^
Accessory circulatory organs 122
6. THE BLOOD 122
7. THE ADIPOSE TISSUE I23
8. THE NERVOUS SYSTEM 123
a. The central nervous system 123
b. The oesophageal sympathetic nervous system 125
c. The ventral sympathetic nervous system 127
d. The peripheral sensory nervous system 128
9. GENERALIZATIONS REGARDING THE SENSE-ORGANS OF INSECTS. . I29
A classification of the sense-organs 129
The cdticular part of the sense-organs 130
10. THE ORGANS OF TOUCH I3I
1 I . THE ORGANS OF TASTE AND SMELL I32
12. THE ORGANS OF SIGHT 134
a. The general features ■ ^34
The two types of eyes ^34
The distinction between ocelli and compound eyes I34
The absence of compound eyes in most of the Apterygota i35
The absence of compound eyes in larvse ^35
h. TheocelU ' ^35
The primary ocelli ^35
The adaptive ocelli - - ^3
The structure of a visual cell ^37
The structure of a primary ocellus , ^37
Ocelli of Ephemerida ^39
c. The compound eyes 39
The physiology of compound eyes H^
The theory of mosaic vision ^^i
^ 142
Day-eyes
Night-eyes ^^"^
Eyes with double function ^43
Divided eyes
144 The tapetum
TABLE OF CONTEXTS
I ;. THE ORGAX5 OF HEARTN-G . ... 1 45
- -- -^^ 145
Thetii: 145
-. scolopophores 146
.146
... 147
: - 147
. ioflarvas 148
::' T- e Acridndae 148
T .eLocastidaeandcrftheGrylHdaB 149
~- : i ; '- : : r :h.e crista acastica i>2
: - 152
Tlie see^e-domes or the oi£accory pores. .. . 154
15. THE REPSODrCTTVE OS.GXSS
The general teauires i^~
Secondary spctnal (^aracters 1=7
The reprodncdve OEgaos of the female 1=7
The general features o€ the <wary 1-7
The wan o£ an ovarian tnbe i r '^
The zt»es ai. an orarian tube. . . 1 5 ^
Theoooientsof anoTariaatobe iSi>
The e^-intHries 15^
Tlie&nictkMisaf thefolHciiiarepctiieiimn 159
Thehgamentof theovaiy I59
The oviduct i59
Tte egg-calyx 1 59
The vagina -~-
The ^lermatheca ■ - -
The btssa copdiatrix ." i - -
.trrve organs erf the male. i^
res of the testes 160
-'- zestiaxlsr folheie . . 161
-^; 162
TABLE OF COXTENTS xvii
1 6. THE SU5PEXSORIA OF THE \^3CERA
The dorsal diaphragm 162
The ventral diaphragm 163
The thread-like suspensoria of the viscera 163
17. SUPPLEMENTARY DEFINITIONS
The oenocytes 163
The pericardial cells - 164
The phagocytic organs 164
The Ught-organs 165
CHAPTER IV I. the extern.\l characteristics of the metamorphosis of insects
a. The egg 166
The shape of the ^g 167
The sctilpture of the shell 167
The microphyle 167
The number of eggs produced by insects 168
Modes of laying eggs i^^
Duration of the egg-state I'O
b. The hatching of young insects in
The hatching spines. ^^^
c. The molting of insects ^/i
General features of the molting of insects 171
The molting fluid ^72
The nvimber of postembryonic molts ^72
Stadia ^72
Instars '
Head measvirements of lar\-ae ^ - 3
The reproduction of lost limbs. ^73
d. Development without metamorphosis 1 74 The Ametabola ^ ' -^
e. Gradual metamorphosis ^'5
The Paurometabola ^^
The term m-mph ^7o
De\-iations from the usual type. ^7o
The Saltitorial Orthoptera ^~
The Cicadas
The Coccidse. .
The Ale\-rodidae
The Aphididse
The Thysanoptera ^77
f. Incomplete metamorphosis ^
The Hemimetabola ^79
The term naiad ^1^
De\-iaTions from the usual type
The Odonata
The Ephemerida
180 180 180 i TABLE OF CONTENTS
g. Complete metamorphosis i8o
The Holometabola i8o
The term larva i8o
The adaptive characteristics of larvae 1 8i
The different types of larvae 183
The prepupa 185
Thepupa 186
The chrysalis 186
Active pupae 187
The cremaster 187
The cocoon 188
Modes of escape from the cocoon 188
The puparium 190
Modes of escape from the puparium 190
The different types of pupae 190
The imago 191
/;. Hypermetamorphosis 191
i. Viviparous insects 191
Viviparity with parthenogenetic reproduction 192
Viviparity with sexual reproduction 193
j. Neoteinia 1 94
2. THE DEVELOPMENT OF APPENDAGES 1 94
a. The development of wings 195
The development of the wings of nymphs and naiads 1 95
The development of the wings in insects with a complete metamorphosis 195
b. The development of legs i97
The development of the legs of nymphs and naiads 198
The development of the legs in insects w'ith a complete metamorphosis 198
c. The development of antennae I99
d. The development of mouth-parts 200
e. The development of the gential appendages 201
3. the development of the head in the muscid/e 202
4. the transformation of the internal organs 204
Index 213
THE STRUCTURE AND METAMORPHOSIS OF INSECTS
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