TABLE OF CONTENTS
Reading edition
PART I. MORPHOLOGY AND PHYSIOLOGY
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Position of Insects in the Animal Kingdom 1
Relations of Insects to Other Arthropoda 2
The Crustacea 4
The Merostomata 5
The Trilobita 5
The Arachnida 6
Relations of Peripatus to insects 9
Relation of Myriopods to insects 11
Relations of the Symphyla to insects 18
Diagnostic or essential characters of Symphyla 22
Insecta (Hexapoda) 26
Diagnostic characters of insects 26
1. EXTERNAL ANATOMY
a. Regions of the body 27
b. The integument (exoskeleton) 28
Chitin 29
c. Mechanical origin and structure of the segments (somites, arthromeres, etc.) 30
d. Mechanical origin of the limbs and of their jointed structure 35
The Head and its Appendages 42
a. The head 42
The labrum 42
The epipharynx and labrum-epipharynx 43
Attachment of the head to the trunk 46
The basal or gular region of the head 46
The occiput 48
The tentorium 49
Number of segments in the head 50
The composition of the head in the Hymenoptera 55
x b. Appendages of the head 57
The antennæ 57
The mandibles 59
The first maxillæ 62
The second maxillæ 68
The hypopharynx 70
Does the hypopharynx represent a distinct segment? 82
The Thorax and its Appendages 86
a. The thorax: its external anatomy 86
The patagia 89
The tegulæ 89
The apodemes 92
The acetabula 94
b. The legs: their structure and functions 95
Tenent hairs 99
Why do insects have but six legs? 100
Loss of limbs by disuse 101
c. Locomotion (walking, climbing, and swimming) 103
Mechanics of walking 103
Locomotion on smooth surfaces 111
Climbing 116
The mode of swimming of insects 116
d. The wings and their structure 120
The veins 121
The squamæ 123
The halteres 124
The thyridium 124
The tegmina and hemelytra 124
The elytra 124
e. Development and mode of origin of the wings 126
Embryonic development of the wings 126
Evagination of the wing outside of the body 132
Extension of the wing; drawing out of the tracheoles 133
f. The primitive origin of the wings 137
The development and structure of the tracheæ and veins of the wing 144
g. Mechanism of flight 148
Theory of insect flight 150
Graber’s views as to the mechanism of the wings, flight, etc. 153
The Abdomen and its Appendages 162
The median segment 163
The cercopoda 164
The ovipositor and sting 167
The styles and genital claspers (Rhabdopoda) 176
Velum penis 181
The suranal plate 181
xi The podical plates or paranal lobes 182
The infra-anal lobe 183
The egg-guide 183
The Armature of Insects: Setæ, Hairs, Scales, Tubercles, Etc. 187
The cuticula 187
Setæ 188
Glandular hairs and spines 190
Scales 193
Development of the scales 195
Spinules, hair-scales, hair-fields, and androconia 197
The Colors of Insects 201
Optical colors 201
Natural colors 203
Chemical and physical nature of the pigment 206
Ontogenetic and phylogenetic development of colors 207
2. INTERNAL ANATOMY
The Muscular System 211
Musculature of a caterpillar 213
Musculature of a beetle 213
Minute structure of the muscles 215
Muscular power of insects 217
The Nervous System 222
a. The nervous system as a whole 222
b. The brain 226
The optic or procerebral segment 231
Procerebral lobes 232
The mushroom or stalked bodies 233
Structure of the mushroom bodies 234
The central body 237
The antennal or olfactory lobes (Deutocerebrum) 237
The œsophageal lobes (Tritocerebrum) 237
c. Histological elements of the brain 238
d. The visceral (sympathetic or stomatogastric) system 238
e. The supraspinal cord 240
f. Modifications of the brain in different orders of insects 240
g. Functions of the nerve-centres and nerves 243
The Sensory Organs 249
a. The eyes and insect vision 249
The simple or single-lensed eye (ocellus) 249
The compound or facetted eye (ommateum) 250
The facet or cornea 250
The crystalline lens or cone 251
xii The pigment 253
The basilar membrane 253
The optic tract 253
Origin of the facetted eye 255
Mode of vision by single eyes or ocelli 255
Mode of vision by facetted eyes 256
The principal use of the facetted eye to perceive the movements of animals 259
How far can insects see? 260
Relation of sight to the color of eyes 260
The color sense of insects 260
b. The organs of smell 264
Historical sketch of our knowledge of the organs of smell 264
Physiological experiments 268
Relation of insects to smelling substances before and after the loss of their antennæ 269
Experiments on the use of the antennæ in seeking for food 270
Experiments testing the influence of the antennæ of the males in seeking the females 270
Structure of the organs of smell in insects 271
c. The organs of taste 281
Structure of the taste organs 282
Distribution in different orders of insects 282
Experimental proof 286
d. The organs of hearing 287
The ears or tympanal and chordotonal sense-organs of Orthoptera and other insects 288
Antennal auditory hairs 292
Special sense-organs in the wings and halteres 293
e. The sounds of insects 293
The Digestive Canal and its Appendages 297
a. The digestive canal 302
The œsophagus 303
The crop or ingluvies 303
The “sucking stomach” or food-reservoir 305
The fore-stomach or proventriculus 306
The œsophageal valve 311
Proventricular valvule 313
The peritrophic membrane 313
The mid-intestine 314
Histology of the mid-intestine 316
The hind-intestine 316
Large intestine 316
The ileum 317
The gastro-ileal folds 317
The colon 317
The rectum 318
xiii The vent (anus) 319
Histology of the digestive canal 320
b. Digestion in insects 324
The mechanism of secretion 326
Absorbent cells 328
The Glandular and Excretory Appendages of the Digestive Canal 331
a. The salivary glands 331
b. The silk or spinning glands, and the spinning apparatus 339
The process of spinning 340
How the thread is drawn out 343
Appendages of the silk-gland (Filippi’s glands) 345
c. The cæcal appendages 347
d. The excretory system (urinary or Malpighian tubes) 348
Primitive number of tubes 353
e. Poison-glands 357
f. Adhesive or cement-glands 360
g. The wax-glands 361
h. “Honey-dew” or wax-glands of Aphids 364
i. Dermal glands in general 365
Defensive or Repugnatorial Scent-Glands 368
Eversible coxal glands 369
Fœtid glands of Orthoptera 369
Anal glands of beetles 372
The blood as a repellent fluid 374
Eversible glands of caddis-worms and caterpillars 375
The osmeterium in Papilio larvæ 377
Dorsal and lateral eversible metameric sacs in other larvæ 377
Distribution of repugnatorial or alluring scent-glands in insects 382
The Alluring or Scent-Glands 391
The Organs of Circulation 397
a. The heart 397
The propulsatory apparatus 401
The supraspinal vessel 403
The aorta 404
The pericardial cells 405
Pulsatile organs of the legs 405
b. The blood 407
The leucocytes 407
c. The circulation of the blood 409
Effects of poisons on the pulsations 412
The Blood Tissue 419
a. The fat-body 419
b. The pericardial fat-body or pericardial cells 420
Leucocytes or phagocytes in connection with the pericardial cells 421
xiv c. The œnocytes 423
d. The phosphorescent organs 424
Physiology of the phosphorescence 426
The Respiratory System 430
a. The tracheæ 431
Distribution of the tracheæ 432
b. The spiracles or stigmata 437
The position and number of pairs of stigmata 439
The closing apparatus of the stigma 441
c. Morphology and homologies of the tracheal system 442
d. The spiral threads or tænidia 444
e. Origin of the tracheæ and of the “spiral thread” 447
Internal, hair-like bodies 451
f. The mechanism of respiration and the respiratory movements of insects 451
g. The air-sacs 456
The use of the air-sacs 457
h. The closed or partly closed tracheal system 459
i. The rectal, tracheal gills, and rectal respiration of larval Odonata and other insects 463
j. Tracheal gills of the larvæ of insects 466
Blood-gills 475
k. Tracheal gills of adult insects 476
The Organs of Reproduction 485
a. The male organs of reproduction 494
The testes 495
The seminal ducts 496
The ejaculatory duct 497
The accessory glands 497
The spermatozoa 497
Formation of the spermatozoön 498
b. The female organs of reproduction 500
The ovaries and the ovarian tubes 500
Origin of incipient eggs in the germ of the testes 504
The bursa copulatrix 505
The spermatheca 506
The colleterial glands 506
The vagina or uterus 507
Signs of copulation in insects 507
PART II. EMBRYOLOGY OF INSECTS
a. The egg 515
Mode of deposition 518
Vitality of eggs 520
xv Appearance and structure of the ripe egg 520
The egg-shell and yolk-membrane 520
The micropyle 522
Internal structure of the egg 524
b. Maturation or ripening of the egg 525
c. Fertilization of the egg 525
d. Division and formation of the blastoderm 526
e. Formation of the first rudiments of the embryo and of the embryonic membranes 531
Formation of the embryonic membranes 532
The gastrula stage 535
Division of the embryo or primitive band into body-segments 536
Differences between the invaginated and overgrown primitive band 538
Revolution of the embryo where the primitive band is invaginated 540
f. Formation of the external form of the body 542
Origin of the body-segments 542
The procephalic lobes 544
Fore-intestine (stomodæum) and hind-intestine (proctodæum), labrum 547
Completion of the head 548
g. The appendages 548
The cephalic appendages 548
The thoracic appendages 550
The abdominal appendages 550
Appendages of the first abdominal segment (pleuropodia) 551
Are the abdominal legs of Lepidoptera and phytophagous Hymenoptera true limbs? 552
The tracheæ 553
h. Nervous system 554
Completion of the definite form of the body 555
i. Dorsal closure and involution of the embryonic membranes 556
j. Formation of the germ-layers 558
k. Farther development of the mesoderm; formation of the body-cavity 563
l. Formation of organs 566
The nervous system 566
Development of the brain 567
Development of the eyes 567
Intestinal canal and glands 569
The salivary glands 570
The urinary tubes 572
The heart 572
The blood-corpuscles 574
Musculature; connective tissue; fat-body 574
The reproductive organs 575
Development of the male germinal glands 579
m. Length of embryonic life 582
n. The process of hatching 583
The hatching spines 585
xviPART III. THE METAMORPHOSES OF INSECTS
a. The nymph as distinguished from the larval stage 593
b. Stages or stadia of metamorphosis 594
c. Ametabolous and metabolous stages 594
The Larva 599
a. The Campodea-form type of larva 600
b. The eruciform type of larva 602
c. Growth and increase in size of the larva 608
d. The process of moulting 609
The number of moults in insects of different orders 615
Reproduction of lost limbs 619
Formation of the cocoon 619
Sanitary conditions observed by the honey-bee larva, and admission of air within the cocoon 623
The Pupa State 625
a. The pupa considered in reference to its adaptation to its surroundings and its relation to phylogeny 631
b. Mode of escape of the pupa from its cocoon 632
c. The cremaster 636
Mode of formation of the cremaster and suspension of the chrysalis in butterflies 637
Formation of the Pupa and Imago in the Holometabolous Insects (the Diptera excepted) 640
a. The Lepidoptera 642
The changes in the head and mouth-parts 646
The change in the internal organs 647
The wings 654
Development of the feet and of the cephalic appendages 654
Embryonic cells and the phagocytes 655
Formation of the femur and of the tibia; transformation of the tarsus 656
The antennæ 657
Maxillæ and labial palpi 658
Process of pupation 660
b. The Hymenoptera 661
Ocular or oculo-cephalic buds 665
The antennal buds 665
The buds of the buccal appendages 665
The buds of the ovipositor 665
Development of the Imago in the Diptera 666
a. Development of the outer body-form 668
Formation of the imago in Corethra 668
Formation of the imago in Culex 670
xvii Formation of the imago in Chironomus 671
Formation of the imago in Muscidæ 673
b. Development of the internal organs of the imago 678
The hypodermis 678
The muscles 680
The digestive canal 681
The tracheal system 683
The nervous system 684
The fat-body 685
Definitive fate of the leucocytes 685
The post-embryonic changes and imaginal buds in the Pupipara (Melophagus) 686
c. General summary 687
Hypermetamorphism 688
Summary of the Facts and Suggestions as to the Causes of Metamorphism 705
Theoretical conclusions; causes of metamorphosis 708
TEXT-BOOK OF ENTOMOLOGY
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