[Illustration Front cover]
THE BUTTERFLY BOOK
[Illustration PLATE I, Frontispiece. SPRING BUTTERFLIES. Pyrameis
Cardui, Linn., ♂ (The Painted Lady); 2. P. Huntera, Fabr., ♂ (Hunter's
Butterfly); 3. Grapta Interrogationis, Fabr., ♂ (The Question Sign); 4.
Colias Philodice, Godt., ♂; 5. Do., ♀ (The Clouded Sulphur); 6. Vanessa
Antiopa, Linn., ♀ (The Mourning Cloak). COPYRIGHTED BY W.J. HOLLAND,
1898]
THE BUTTERFLY BOOK
A POPULAR GUIDE TO A KNOWLEDGE
OF THE BUTTERFLIES OF
NORTH AMERICA
BY
W.J. HOLLAND, PH.D., D.D., LL.D.
CHANCELLOR OF THE WESTERN UNIVERSITY OF PENNSYLVANIA; DIRECTOR OF THE
CARNEGIE MUSEUM, PITTSBURGH, PA.; FELLOW OF THE ZOÖLOGICAL AND
ENTOMOLOGICAL SOCIETIES OF LONDON; MEMBER OF THE ENTOMOLOGICAL SOCIETY
OF FRANCE, ETC., ETC.
WITH 48 PLATES IN COLOR-PHOTOGRAPHY, REPRODUCTIONS
OF BUTTERFLIES IN THE AUTHOR'S COLLECTION,
AND MANY TEXT ILLUSTRATIONS PRESENTING
MOST OF THE SPECIES FOUND IN THE UNITED STATES
[Illustration]
GARDEN CITY NEW YORK
DOUBLEDAY, PAGE & COMPANY
1922
COPYRIGHT, 1898,
BY W.J. HOLLAND.
PRINTED IN THE UNITED STATES
AT
THE COUNTRY LIFE PRESS, GARDEN CITY, N.Y.
TO MY GOOD WIFE
AND MY TWO BONNY BOYS,
THE COMPANIONS OF MY LEISURE HOURS
AND MY VACATION RAMBLES,
I DEDICATE THIS BOOK,
WITHOUT ASKING THEIR PERMISSION
PREFACE
At some time or other in the life of every healthy young person there
appears to be developed what has been styled "the collecting mania."
Whether this tendency is due to the natural acquisitiveness of the human
race, to an innate appreciation of the beautiful and the curious, or to
the development of an instinct such as is possessed by the bower-bird,
the magpie, and the crow, which have the curious habit of gathering
together and storing away trifles which are bright and attractive to the
eye, I leave to students of the mind to decide. The fact is patent that
there is no village without its youthful enthusiast whose collection of
postage-stamps is dear to his heart, and no town in which there are not
amateur geologists, archæologists, botanists, and zoölogists, who are
eagerly bent upon the formation of collections of such objects as
possess an attraction for them.
One of the commonest pursuits of boyhood is the formation of a
collection of insects. The career of almost every naturalist of renown
has been marked in its early stages by a propensity to collect these
lower, yet most interesting and instructive, forms of animal life. Among
the insects, because of their beauty, butterflies have always held a
foremost place in the regard of the amateur collector. For the lack,
however, of suitable instruction in the art of preserving specimens,
and, above all, by reason of the almost entire lack of a convenient and
well-illustrated manual, enabling the collector to identify, name, and
properly classify the collections which he is making, much of the labor
expended in this direction in the United States and Canada fails to
accomplish more than the furnishing of temporary recreation. It is
otherwise in Europe. Manuals, comprehensive in scope, and richly adorned
with illustrations of the leading insect forms of Great Britain and the
Continent, have been produced in great numbers in recent years in
England, France, and Germany. The result is that the youthful collector
enters the field in those countries in the possession of a vast
advantage over his less fortunate American fellow. It is to meet this
want on this side of the Atlantic that this volume has been written. Its
aim is to guide the amateur collector in right paths and to prepare him
by the intelligent accomplishment of his labors for the enjoyment of
still wider and more difficult researches in this and allied fields of
human knowledge. The work is confined to the fauna of the continent of
North America north of the Rio Grande of Texas. It is essentially
popular in its character. Those who seek a more technical treatment must
resort to the writings of others.
If I shall succeed in this book in creating a more wide-spread interest
in the world of insect life and thereby diverting attention in a measure
from the persecuted birds, which I love, but which are in many species
threatened with extinction by the too eager attentions which they are
receiving from young naturalists, who are going forth in increased
numbers with shot-gun in hand, I think I shall render a good service to
the country.
I flatter myself that I have possessed peculiar facilities for the
successful accomplishment of the undertaking I have proposed to myself,
because of the possession of what is admitted to be undoubtedly the
largest and most perfect collection of the butterflies of North America
in existence, containing the types of W.H. Edwards, and many of those
of other authors. I have also enjoyed access to all the other great
collections of this country and Europe, and have had at my elbow the
entire literature relating to the subject.
The successful development in recent months of the process of
reproducing in colors photographic representations of objects has been
to a certain degree the argument for the publication of this book at the
present time. A few years ago the preparation of such a work as this at
the low price at which it is sold would have been an utter
impossibility. "The Butterflies of North America," by W.H. Edwards,
published in three volumes, is sold at one hundred and fifty dollars,
and, as I know, is sold even at this price below the cost of
manufacture. "The Butterflies of New England," by Dr. S.H. Scudder, in
three volumes, is sold at seventy-five dollars, and likewise represents
at this price only a partial return to the learned author for the
money, labor, and time expended upon it. The present volume, while not
pretending to vie in any respect with the magnificence of the
illustrations contained in these beautiful and costly works,
nevertheless presents in recognizable form almost every species figured
in them, and in addition a multitude of others, many of which have never
before been delineated. So far as possible I have employed, in making
the illustrations, the original types from which the author of the
species drew his descriptions. This fact will no doubt add greatly to
the value of the work, as it will not only serve as a popular guide, but
have utility also for the scientific student.
I am under obligations to numerous friends and correspondents who have
aided me, and take the present opportunity to extend to them all my
hearty thanks for the generous manner in which they have assisted me in
my pleasant task. I should fail, however, to follow the instincts of a
grateful heart did I not render an especial acknowledgment to Mr. W.H.
Edwards, of Coalburg, West Virginia, and Dr. Samuel H. Scudder, of
Cambridge, Massachusetts. Justly esteemed as the two foremost
lepidopterists of America, it is my honor to claim them as personal
friends, whose kindness has much aided me in this labor of scientific
love which I have undertaken. For the kind permission given me by Dr.
Scudder to use various illustrations contained in the "Butterflies of
New England" and other works, I am profoundly grateful.
I am under obligations to Messrs. Charles Scribner's Sons for permission
to use the cuts numbered 46-49, 51-56, 59, 61, 62, and 73, which are
taken from the work entitled "Taxidermy and Zoölogical Collecting," by
W.T. Hornaday, and to the authorities of the United States National
Museum and the heirs of the late Professor C.V. Riley for other
illustrations.
Should this book find the favor which I have reason to think it
deserves, I shall endeavor shortly to follow it by the preparation of a
similar work upon the moths of the United States and Canada.
OFFICE OF THE CHANCELLOR, W.J.H.
WESTERN UNIVERSITY OF PENNSYLVANIA,
August 16, 1898.
TABLE OF CONTENTS
INTRODUCTION
CHAP. PAGE
I. THE LIFE-HISTORY AND ANATOMY OF BUTTERFLIES 3-25
_The Eggs of Butterflies. Caterpillars_: Structure,
Form, Color, etc.; Moults; Food of Caterpillars; Duration of Larval
State; Transformation. _The Pupa, or Chrysalis_: The Form of
Chrysalids; Duration of Pupal Life; The Transformation from the
Chrysalis to the Imago. _Anatomy of Butterflies_: The Head; The
Thorax; The Abdomen; The Legs; The Wings; Internal Organs;
Polymorphism and Dimorphism; Albinism and Melanism; Monstrosities;
Mimicry. _The Distribution of Butterflies._
II. THE CAPTURE, PREPARATION, AND PRESERVATION OF
SPECIMENS 26-57
_Collecting Apparatus_: Nets; Collecting-Jars; Field-Boxes; The Use
of the Net; Baits; Beating. _The Breeding of Specimens_: How to Get
the Eggs of Butterflies; Breeding-Cages; How to Find Caterpillars;
Hibernating Caterpillars. _The Preservation of Specimens_: Papering
Specimens; Mounting Butterflies; Relaxing Specimens; The Preparation
and Preservation of Butterfly Eggs; The Preservation of Chrysalids;
The Preservation of Caterpillars. _The Preservation and
Arrangement of Collections_: Boxes; Cabinets and Drawers; Labeling;
Arrangement of Specimens; Insect Pests; Greasy Specimens;
Mould; Repairing Specimens; Packing and Forwarding Specimens;
Pins; The Forceps.
III. THE CLASSIFICATION OF BUTTERFLIES 58-68
The Place of Butterflies in the Animal Kingdom; The Principles of
Scientific Arrangement; The Species; The Genus; The Family, etc.;
Scientific Names; Synonyms; Popular Names.
IV. BOOKS ABOUT NORTH AMERICAN BUTTERFLIES 69-74
Early Writers; Later Writers; Periodicals.
THE BOOK
PAGE
THE BUTTERFLIES OF NORTH AMERICA NORTH OF MEXICO.
Family I. _Nymphalidae_, the Brush-footed Butterflies 77
Subfamily _Euplaeinae_, the Milkweed Butterflies 80
Subfamily _Ithomiinae_, the Long-winged Butterflies 85
Subfamily _Heliconiinae_, the Heliconians 91
Subfamily _Nymphalinae_, the Nymphs 93
Subfamily _Satyrinae_, the Satyrs, Meadow-browns,
and Arctics 197
Subfamily _Libytheinae_, the Snout-butterflies 226
Family II. _Lemoniidae_ 228
Subfamily _Erycininae_, the Metal-marks 228
Family III. _Lycaenidae_ 236
Subfamily _Lycaeninae_, the Hair-streaks,
the Blues, and the Coppers 236
Family IV. _Papilionidae_, the Swallowtails and Allies 272
Subfamily _Pierinae_, the Whites, the Sulphurs,
the Orange-tips 272
Subfamily _Papilioninae_, the Parnassians and Swallowtails 304
Family V. _Hesperiidae_, the Skippers 318
Subfamily _Pyrrhopyginae_ 319
Subfamily _Hesperiinae_, the Hesperids 320
Subfamily _Pamphilinae_ 339
Subfamily _Megathyminae_, genus Megathymus 367
DIGRESSIONS AND QUOTATIONS
PAGE
Immortality (Sigourney) 57
Hugo's "Flower to Butterfly" (Translated by Eugene Field) 74
Superstitions (Frank Cowan) 90
Luther's Saddest Experience (Yale Literary Magazine, 1852) 100
A Race after a Butterfly 127
Suspicious Conduct 136
Collecting in Japan 149
Faunal Regions 161
Widely Distributed Butterflies 171
The Butterflies' Fad (Ella Wheeler Wilcox) 186
Fossil Insects 195
In the Face of the Cold 224
Uncle Jotham's Boarder (Annie Trumbull Slosson) 233
Mimicry 235
The Utility of Entomology 256
Size 271
Instinct 280
Red Rain (Frank Cowan) 299
For a Design of a Butterfly Resting on a Skull (Mrs. Hemans) 303
The Caterpillar and the Ant (Allan Ramsay) 316
Collections and Collectors 337
Exchanges 344
LIST OF ILLUSTRATIONS IN TEXT
FIG. PAGE
1. Egg of Basilarchia disippus, magnified 3
2. Egg of Basilarchia disippus, natural size 3
3. Egg of Papilio turnus, enlarged 4
4. Egg of Anosia plexippus, magnified 4
5. Egg of Anosia plexippus, natural size 4
6. Egg of Anthocharis genutia, magnified 4
7. Egg of Lycæna pseudargiolus, magnified 4
8. Egg of Melitæa phaëton, magnified 4
9. Micropyle of egg of Pieris oleracea, magnified 5
10. Eggs of Grapta comma, magnified 5
11. Eggs of Vanessa antiopa, magnified 5
12. Caterpillar of Papilio philenor 6
13. Head of caterpillar of Papilio asterias, magnified 6
14. Head of caterpillar of Anosia plexippus, magnified 6
15. Head of caterpillar of Anosia plexippus, side view, enlarged 7
16. Caterpillar of Anosia plexippus, natural size 7
17. Fore leg of caterpillar of Vanessa antiopa, enlarged 7
18. Anterior segments of caterpillar of A. plexippus 7
19. Proleg of caterpillar of Vanessa antiopa, enlarged 7
20. Caterpillar of Basilarchia disippus 8
21. Early stages of goatweed butterfly 9
22. Head of caterpillar of Papilio troilus 9
23. Caterpillar of milkweed butterfly changing into chrysalis 11
24. Chrysalis of milkweed butterfly 12
25. Chrysalis of Papilio philenor 12
26. Caterpillar and chrysalis of Pieris protodice 12
27. Chrysalis of Pieris oleracea 13
28. Butterfly emerging from chrysalis 13
29. Head of milkweed butterfly, showing parts 14
30. Cross-section of sucking-tube of butterfly 15
31. Longitudinal section of the head of the milkweed butterfly 15
32. Interior structure of head of milkweed butterfly 16
33. Labial palpus of butterfly 16
34. Legs of butterfly 17
35. Parts of leg of butterfly 17
36. Scales on wing of butterfly 18
37. Androconia from wing of butterfly 18
38. Outline of wing of butterfly 20
39. Arrangement of scales on the wing of a butterfly 20
40. Figure of wing, showing names of veins 21
41. Internal anatomy of caterpillar of milkweed butterfly 22
42. Internal anatomy of milkweed butterfly 23
43. Plan for folding net-ring 27
44. Insect-net 27
45. Plan for making a cheap net 27
46. Cyanide-jar 29
47. Paper cover for cyanide 29
48. Method of pinching a butterfly 30
49. Cheap form of breeding-cage 35
50. Breeding-cage 36
51. Butterfly in envelope 38
52. Method of making envelopes 38
53. Setting-board 39
54. Setting-block 39
55. Butterfly on setting-block 39
56. Setting-needle 40
57. Setting-board with moth upon it 40
58. Butterfly pinned on setting-board 41
59. Drying-box 41
60. Drying-box 42
61. Apparatus for inflating larvæ 45
62. Tip of inflating-tube 46
63. Drying-oven 46
64. Drying-oven 47
65. Detail drawing of book-box 48
66. Detail drawing of box 48
67. Detail drawing of box 49
68. Insect-box 49
69. Detail drawing of drawer for cabinet 51
70. Detail drawing for paper bottom of box to take place of cork 52
71. Manner of arranging specimens in cabinet or box 52
72. Naphthaline cone 53
73. Butterflies packed for shipment 55
74. Forceps 56
75. Forceps 57
76. Antennæ of butterfly 61
77. Antennæ of moths 62
78. Neuration of genus Anosia 81
79. Swarm of milkweed butterflies, photographed at night 83
80. Neuration of genus Mechanitis 86
81. Neuration of genus Ceratinia 88
82. Neuration of genus Dircenna 89
83. Fore leg of female Dircenna klugi 89
84. Neuration of genus Heliconius 91
85. Young caterpillar of Vanessa antiopa 94
86. Neuration of genus Colænis 95
87. Neuration of genus Dione 96
88. Neuration of genus Euptoieta 98
89. Neuration of genus Argynnis 101
90. Neuration of genus Brenthis 129
91. Neuration of genus Melitæa 138
92. Neuration of genus Phyciodes 151
93. Neuration of genus Eresia 157
94. Neuration of genus Synchloë 159
95. Neuration of genus Grapta 163
96. Neuration of genus Vanessa 167
97. Neuration of genus Pyrameis 170
98. Neuration of genus Junonia 172
99. Neuration of genus Anartia 174
100. Neuration of genus Hypanartia 175
101. Neuration of genus Eunica 176
102. Neuration of genus Cystineura 177
103. Neuration of genus Callicore 178
104. Neuration of genus Timetes 179
105. Neuration of genus Hypolimnas 181
106. Neuration of genus Basilarchia 182
107. Leaf cut away at end by the caterpillar of Basilarchia 183
108. Hibernaculum of caterpillar of Basilarchia 183
109. Neuration of genus Adelpha 187
110. Neuration of genus Chlorippe 188
111. Neuration of genus Pyrrhanæa 192
112. Neuration of genus Ageronia 193
113. Neuration of genus Victorina 195
114. Neuration of genus Debis 199
115. Neuration of genus Satyrodes 200
116. Neuration of genus Neonympha 201
117. Neuration of genus Coenonympha 205
118. Neuration of genus Erebia 208
119. Neuration of genus Geirocheilus 211
120. Neuration of genus Neominois 212
121. Neuration of genus Satyrus 214
122. Neuration of genus OEneis 219
123. Caterpillars of OEneis macouni 221
124. Neuration of genus Libythea 226
125. Neuration of base of hind wing of genus Lemonias 228
126. Neuration of genus Lemonias 229
127. Neuration of genus Calephelis 232
128. Neuration of genus Eumæus 237
129. Neuration of Thecla edwardsi 238
130. Neuration of Thecla melinus 242
131. Neuration of Thecla damon 246
132. Neuration of Thecla niphon 249
133. Neuration of Thecla titus 250
134. Neuration of genus Feniseca 251
135. Neuration of genus Chrysophanus 252
136. Neuration of Lycæna pseudargiolus 267
137. Neuration of Lycæna comyntas 268
138. Neuration of genus Dismorphia 273
139. Neuration of genus Neophasia 274
140. Neuration of genus Tachyris 276
141. Neuration of genus Pieris 277
142. Neuration of genus Nathalis 281
143. Neuration of genus Euchloë 282
144. Neuration of genus Catopsilia 286
145. Neuration of genus Kricogonia 287
146. Neuration of genus Meganostoma 288
147. Neuration of genus Colias 289
148. Neuration of genus Terias 295
149. Neuration of genus Parnassius 305
An Astronomer's Conception of an Entomologist 317
150. Head and antenna of genus Pyrrhopyge 319
151. Neuration of genus Pyrrhopyge 319
152. Neuration of genus Eudamus 321
153. Antenna and neuration of genus Plestia 322
154. Neuration of genus Epargyreus 323
155. Neuration of genus Thorybes 324
156. Neuration of genus Achalarus 326
157. Antenna and neuration of genus Hesperia 327
158. Neuration of genus Systasea 329
159. Neuration of genus Pholisora 330
160. Neuration of genus Thanaos 332
161. Neuration of genus Amblyscirtes 340
162. Neuration of genus Pamphila 342
163. Neuration of genus Oarisma 343
164. Neuration of genus Ancyloxypha 345
165. Neuration of genus Copæodes 346
166. Neuration of genus Erynnis 347
167. Neuration of genus Thymelicus 351
168. Neuration of genus Atalopedes 352
169. Neuration of genus Polites 353
170. Neuration of genus Hylephila 354
171. Neuration of genus Prenes 355
172. Neuration of genus Calpodes 355
173. Neuration of genus Lerodea 356
174. Neuration of genus Limochores 357
175. Neuration of genus Euphyes 360
176. Neuration of genus Oligoria 361
177. Neuration of genus Poanes 362
178. Neuration of genus Phycanassa 362
179. Neuration of genus Atrytone 364
180. Neuration of genus Lerema 366
181. Megathymus yuccæ, ♀ 367
182. Larva of Megathymus yuccæ 368
183. Chrysalis of Megathymus yuccæ 368
The Popular Conception of an Entomologist 369
LIST OF COLORED PLATES
Produced by the color-photographic process of the Chicago Colortype
Company, 1205 Roscoe Street, Chicago, Ill.
FACING
PAGE
I. Spring Butterflies _Frontispiece_
II. Caterpillars of Papilionidæ and Hesperiidæ 6
III. Caterpillars of Nymphalidæ 18
IV. Chrysalids in Color and in Outline--Nymphalidæ 30
V. Chrysalids in Color and in Outline--Nymphalidæ,
Lycænidæ, Pierinæ 44
VI. Chrysalids in Color and in Outline--Papiloninæ
and Hesperiidæ 58
VII. Anosia and Basilarchia 80
VIII. Ithomiinæ, Heliconius, Dione, Colænis, and Euptoieta 88
IX. Argynnis 100
X. Argynnis 104
XI. Argynnis 108
XII. Argynnis 112
XIII. Argynnis 116
XIV. Argynnis 122
XV. Brenthis 130
XVI. Melitæa 138
XVII. Melitæa, Phyciodes, Eresia 152
XVIII. Argynnis, Brenthis, Melitæa, Phyciodes, Eresia,
Synchloë, Debis, Geirocheilus 156
XIX. Grapta, Vanessa 164
XX. Grapta, Vanessa, Junonia, Anartia, Pyrameis 168
XXI. Timetes, Hypolimnas, Eunica, Callicore 178
XXII. Basilarchia, Adelpha 184
XXIII. Chlorippe 190
XXIV. Pyrrhanæa, Ageronia, Synchloë, Cystineura, Hypanartia,
Victorina 196
XXV. Satyrodes, Coenonympha, Neonympha, Neominois, Erebia 204
XXVI. Satyrus 214
XXVII. OEneis 220
XXVIII. Libythea, Lemonias, Calephelis, Eumæus, Chrysophanus,
Feniseca 228
XXIX. Chrysophanus, Thecla 236
XXX. Thecla, Lycæna 246
XXXI. Lycæna 256
XXXII. Lycæna, Thecla, Nathalis, Euchloë 266
XXXIII. Catopsilia, Pyrameis 272
XXXIV. Euchloë, Neophasia, Pieris, Kricogonia 280
XXXV. Tachyris, Pieris, Colias 288
XXXVI. Meganostoma, Colias 294
XXXVII. Terias, Dismorphia 298
XXXVIII. Papilio 302
XXXIX. Parnassius 306
XL. Papilio 310
XLI. Papilio 314
XLII. Papilio 316
XLIII. Papilio, Colias, Pyrameis, Epargyreus 318
XLIV. Papilio 323
XLV. Papilio, Pholisora, Eudamus, Achalarus, Pyrrhopyge,
Plestia, Calpodes, Thanao 330
XLVI. Hesperiidæ 338
XLVII. Hesperiidæ 350
XLVIII. Hesperiidæ and Colias eurytheme 360
INTRODUCTION
INTRODUCTION
CHAPTER I
THE LIFE-HISTORY AND ANATOMY OF BUTTERFLIES
"The study of butterflies,--creatures selected as the types of
airiness and frivolity,--instead of being despised, will some day
be valued as one of the most important branches of biological
science."--BATES, _Naturalist on the Amazons_.
In studying any subject, it is always well, if possible, to commence at
the beginning; and in studying the life of animals, or of a group of
animals, we should endeavor to obtain a clear idea at the outset of the
manner in which they are developed. It is a familiar saying that "all
life is from an egg." This statement is scientifically true in wide
fields which come under the eye of the naturalist, and butterflies are
no exception to the rule.
THE EGGS OF BUTTERFLIES
[Illustration FIG. 1.--Egg of _Basilarchia disippus_, magnified 30
diameters (Riley).]
[Illustration FIG. 2.--Egg of _Basilarchia disippus_, natural size, at
the end of under surface of leaf (Riley).]
The eggs of butterflies consist of a membranous shell containing a fluid
mass composed of the germ of the future caterpillar and the liquid food
which is necessary for its maintenance and development until it escapes
from the shell. The forms of these eggs are various. Some are spherical,
others hemispherical, conical, and cylindrical. Some are barrel-shaped;
others have the shape of a cheese, and still others have the form of a
turban. Many of them are angled, some depressed at the ends. Their
surface is variously ornamented. Sometimes they are ribbed, the ribs
running from the center outwardly and downwardly along the sides like
the meridian lines upon a globe. Between these ribs there is frequently
found a fine network of raised lines variously arranged. Sometimes the
surface is covered with minute depressions, sometimes with a series of
minute elevations variously disposed. As there is great variety in the
form of the eggs, so also there is great variety in their color. Brown,
blue, green, red, and yellow eggs occur. Greenish or greenish-white are
common tints. The eggs are often ornamented with dots and lines of
darker color. Species which are related to one another show their
affinity even in the form of their eggs. At the upper end of the eggs of
insects there are one or more curious structures, known as micropyles
(little doors), through which the spermatozoa of the male find ingress
and they are fertilized. These can only be seen under a good microscope.
[Illustration FIG. 3.--Egg of _Papilio turnus_, greatly magnified.]
[Illustration FIG. 4.--Egg of _Anosia plexippus_, magnified 30
diameters (Riley).]
[Illustration FIG. 5.--Egg of _Anosia plexippus_, natural size, on
under side of leaf (Riley).]
[Illustration FIG. 6.--Egg of _Anthocharis genutia_, magnified 20
diameters.]
[Illustration FIG. 7.--Turban-shaped egg of _Lycæna pseudargiolus_,
greatly magnified.]
[Illustration FIG. 8.--Egg of _Melitæa phaëton_, greatly magnified.]
The eggs are laid upon the food-plant upon which the caterpillar, after
it is hatched, is destined to live, and the female reveals wonderful
instinct in selecting plants which are appropriate to the development of
the larva. As a rule, the larvæ are restricted in the range of their
food-plants to certain genera, or families of plants.
[Illustration FIG. 9.--Upper end of egg of _Pieris oleracea_, greatly
magnified, showing the micropyle.]
[Illustration FIG. 10.--Egg of _Grapta comma_, laid in string-like
clusters on the under side of leaf. (Magnified.)]
The eggs are deposited sometimes singly, sometimes in small clusters,
sometimes in a mass. Fertile eggs, a few days after they have been
deposited, frequently undergo a change of color, and it is often
possible with a magnifying-glass to see through the thin shell the form
of the minute caterpillar which is being developed within the egg.
Unfruitful eggs generally shrivel and dry up after the lapse of a short
time.
The period of time requisite for the development of the embryo in the
egg varies. Many butterflies are single-brooded; others produce two or
three generations during the summer in temperate climates, and even more
generations in subtropical or tropical climates. In such cases an
interval of only a few days, or weeks at the most, separates the time
when the egg was deposited and the time when the larva is hatched. When
the period of hatching, or emergence, has arrived, the little
caterpillar cuts its way forth from the egg through an opening made
either at the side or on the top. Many species have eggs which appear to
be provided with a lid, a portion of the shell being separated from the
remainder by a thin section, which, when the caterpillar has reached the
full limit allowed by the egg, breaks under the pressure of the
enlarging embryo within, one portion of the egg flying off, the
remainder adhering to the leaf or twig upon which it has been deposited.
[Illustration FIG. 11.--Eggs of _Vanessa antiopa_, laid in a mass on a
twig.]
CATERPILLARS
_Structure, Form, Color, etc._--The second stage in which the insects we
are studying exist is known as the larval stage. The insect is known as
a larva, or a caterpillar. In general caterpillars have long, worm-like
bodies. Frequently they are thickest about the middle, tapering before
and behind, flattened on the under side. While the cylindrical shape is
most common, there are some families in which the larvæ are short, oval,
or slug-shaped, sometimes curiously modified by ridges and prominences.
The body of the larvæ of lepidoptera consists normally of thirteen
rings, or segments, the first constituting the head.
[Illustration FIG. 12.--Caterpillar of _Papilio philenor_ (Riley).]
[Illustration FIG. 13.--Head of caterpillar of _Papilio asterias_,
front view, enlarged.]
[Illustration FIG. 14.--Head of caterpillar of _Anosia plexippus_,
lower side, magnified 10 diameters: _lb_, labrum, or upper lip; _md_,
mandibles; _mx_, maxilla, with two palpi; _lm_, labium, or lower lip,
with one pair of palpi; _s_, spinneret; _a_, antenna; _o_, ocelli.
(After Burgess.)]
The head is always conspicuous, composed of horny or chitinous material,
but varying exceedingly in form and size. It is very rarely small and
retracted. It is generally large, hemispherical, conical, or bilobed. In
some families it is ornamented by horn-like projections. On the lower
side are the mouth-parts, consisting of the upper lip, the mandibles,
the antennæ, or feelers, the under lip, the maxillæ, and two sets of
palpi, known as the maxillary and the labial palpi. In many genera the
labium, or under lip, is provided with a short, horny projection known
as the spinneret, through which the silk secreted by the caterpillar is
passed. On either side, just above the mandibles, are located the eyes,
or ocelli, which in the caterpillar are simple, round, shining
prominences, generally only to be clearly distinguished by the aid of a
magnifying-glass. These ocelli are frequently arranged in series on each
side. The palpi are organs of touch connected with the maxillæ and the
labium, or under lip, and are used in the process of feeding, and also
when the caterpillar is crawling about from place to place. The
larva appears to guide itself in great part by means of the palpi.
+--------------------------------------------------------------+
| |
| EXPLANATION OF PLATE II |
| |
| Reproduced, with the kind permission of Dr. S.H. Scudder, |
| from "The Butterflies of New England," vol. iii, Plate 76. |
| |
| |
| |
| CATERPILLARS OF PAPILIONIDÆ AND HESPERIIDÆ |
| |
| 1. _Colias eurytheme._ |
| 2. _Callidryas eubule._ |
| 3. _Terias lisa._ |
| 4. _Callidryas eubule._ |
| 5. _Euchloë genutia._ |
| 6. _Terias nicippe._ |
| 7. _Pieris protodice._ |
| 8. _Pieris napi_, var. _oleracea_. |
| 9. _Pieris napi_, var. _oleracea_. |
| 10. _Colias philodice._ |
| 11. _Pieris rapæ._ |
| 12. _Pieris rapæ._ |
| 13. _Papilio philenor._ |
| 14. _Papilio ajax._ |
| 15. _Papilio turnus._ Just before pupation. |
| 16. _Papilio cresphontes._ |
| 17. _Papilio asterias._ In second stage. |
| 18. _Papilio troilus._ |
| 19. _Papilio troilus._ In third stage; plain. |
| 20. _Papilio philenor._ |
| 21. _Papilio philenor._ In third stage; dorsal view. |
| 22. _Papilio troilus._ In third stage; dorsal view. |
| 23. _Achalarus lycidas._ Dorsal view. |
| 24. _Papilio asterias._ In fourth stage; dorsal view. |
| 25. _Thorybes pylades._ |
| 26. _Papilio turnus._ Dorsal view. |
| 27. _Papilio asterias._ |
| 28. _Papilio turnus._ |
| 29. _Thorybes pylades._ |
| 30. _Epargyreus tityrus._ |
| 31. _Epargyreus tityrus._ |
| 32. _Thorybes bathyllus._ |
| 33. _Epargyreus tityrus._ |
| 34. _Eudamus proteus._ |
| 35. _Epargyreus tityrus._ In third stage. |
| |
| [Illustration PLATE II.] |
+--------------------------------------------------------------+
[Illustration FIG. 15.--Head of caterpillar of _Anosia plexippus_, side
view, showing ocelli.]
[Illustration FIG 16.--Caterpillar of _Anosia plexippus_, milkweed
butterfly (Riley).]
The body of the caterpillar is covered by a thin skin, which often lies
in wrinkled folds, admitting of great freedom of motion. The body is
composed, as we have seen, of rings, or segments, the first three of
which, back of the head, correspond to the thorax of the perfect insect,
and the last nine to the abdomen of the butterfly. On each ring, with
the exception of the second, the third, and the last, there is found on
either side a small oval opening known as a spiracle, through which the
creature breathes. As a rule, the spiracles of the first and eleventh
rings are larger in size than the others.
[Illustration FIG. 17.--Fore leg of caterpillar of _Vanessa antiopa_,
enlarged.]
[Illustration FIG. 18.--Anterior segments of caterpillar of milkweed
butterfly, showing thoracic or true legs (Riley).]
[Illustration FIG. 19.--Proleg of caterpillar of _Vanessa antiopa_,
enlarged.]
Every caterpillar has on each of the first three segments a pair of
legs, which are organs composed of three somewhat horny parts covered
and bound together with skin, and armed at their extremities by a sharp
claw (Fig. 17). These three pairs of feet in the caterpillar are always
known as the fore legs, and correspond to the six which are found in the
butterfly or the moth. In addition, in most cases, we find four pairs of
prolegs on the under side of the segments from the sixth to the ninth,
and another pair on the last segment, which latter pair are called the
anal prolegs. These organs, which are necessary to the life of the
caterpillar, do not reappear in the perfect insect, but are lost when
the transformation from the caterpillar to the chrysalis takes place.
There are various modifications of this scheme of foot-like appendages,
only the larger and more highly developed forms of lepidoptera having as
many pairs of prolegs as have been enumerated.
[Illustration FIG. 20.--Caterpillar of _Basilarchia disippus_, the
viceroy, natural size (Riley).]
The bodies of caterpillars are variously ornamented: many of them are
quite smooth; many are provided with horny projections, spines, and
eminences. The coloration of caterpillars is as remarkable in the
variety which it displays as is the ornamentation by means of the
prominences of which we have just spoken. As caterpillars, for the most
part, feed upon growing vegetation, multitudes of them are green in
color, being thus adapted to their surroundings and securing a measure
of protection. Many are brown, and exactly mimic the color of the twigs
and branches upon which they rest when not engaged in feeding. Not a few
are very gaily colored, but in almost every case this gay coloring is
found to bear some relation to the color of the objects upon which they
rest.
Caterpillars vary in their social habits. Some species are gregarious,
and are found in colonies. These frequently build for themselves
defenses, weaving webs of silk among the branches, in which they are in
part protected from their enemies and also from the inclemencies of the
weather. Most caterpillars are, however, solitary, and no community life
is maintained by the vast majority of species. Many species have the
habit of drawing together the edges of a leaf, in which way they form a
covering for themselves. The caterpillars of some butterflies are
wood-boring, and construct tunnels in the pith, or in the soft layers of
growing plants. In these cases, being protected and concealed from view,
the caterpillars are generally white in their coloration, resembling in
this respect the larvæ of wood-boring beetles. A most curious phenomenon
has within comparatively recent years been discovered in connection
with the larval stage of certain small butterflies belonging to the
family _Lycoenidoe_. The caterpillars are carnivorous, or rather
aphidivorous; they live upon aphids, or plant-lice, and scale-insects,
and cover themselves with the white exudations or mealy secretions of
the latter. This trait is characteristic of only one of our North
American species, the Harvester (_Feniseca tarquinius_).
[Illustration FIG. 21.--Early stages of the goatweed butterfly: _a_,
caterpillar; _b_, chrysalis; _c_, leaf drawn together at edges to form a
nest. (Natural size.) (Riley.)]
In addition to being protected from enemies by having colors which
enable them to elude observation, as has been already stated, some
caterpillars are provided with other means of defense. The caterpillars
of the swallowtail butterflies are provided with a bifurcate or forked
organ, generally yellow in color, which is protruded from an opening in
the skin back of the head, and which emits a powerful odor (Fig. 22).
This protrusive organ evidently exists only for purposes of defense, and
the secretion of the odor is analogous to the secretion of evil odors by
some of the vertebrate animals, as the skunk. The majority of
caterpillars, when attacked by insect or other enemies, defend
themselves by quickly hurling the anterior part of the body from side to
side.
[Illustration FIG. 22.--Head of caterpillar of _Papilio troilus_, with
scent-organs, or _osmateria_, protruded.]
_Moults._--Caterpillars in the process of growth and development from
time to time shed their skins. This process is called _moulting_.
Moulting takes place, as a rule, at regular intervals, though there are
exceptions to this rule. The young larva, having emerged from the egg,
grows for a number of days, until the epidermis, or true skin, has
become too small. It then ceases feeding, attaches itself firmly to some
point, and remains quiet for a time. During this period certain changes
are taking place, and then the skin splits along the middle line from
the head to the extremity of the last segment, and the caterpillar
crawls forth from the skin, which is left behind it, attached to the
leaf or branch to which it was fastened. The skin of the head sometimes
remains attached to the head of the caterpillar for a time after it has
moulted, and then falls off to the ground. Ordinarily not more than
five, and frequently only four, moults take place between hatching from
the egg and the change into the chrysalis. In cases where caterpillars
hibernate, or pass the winter in inaction, a long interval necessarily
elapses between moults. Some arctic species are known in which the
development from the egg to the perfect insect covers a period of two or
three years, long periods of hibernation under the arctic snows taking
place. The manner in which the caterpillar withdraws itself from its
exuviæ, or old skin, is highly interesting. Every little spine or rough
prominence is withdrawn from its covering, and the skin is left as a
perfect cast of the creature which has emerged from it, even the hairs
and spines attached to the skin being left behind and replaced by
others.
_The Food of the Caterpillar._--The vast majority of the caterpillars of
butterflies subsist upon vegetable food, the only exceptions being the
singular one already noted in which the larvæ feed upon scale-insects.
Some of the _Hesperiidæ_, a group in which the relationship between
butterflies and moths is shown, have larvæ which burrow in the roots and
stems of vegetation.
_Duration of the Larval State._--The duration of the larval state varies
greatly. In temperate climates the majority of species exist in the
caterpillar state for from two to three months, and where hibernation
takes place, for ten months. Many caterpillars which hibernate do so
immediately after emerging from the egg and before having made the first
moult. The great majority, however, hibernate after having passed one or
more moults. With the approach of spring they renew their feeding upon
the first reappearance of the foliage of their proper food-plant, or are
transformed into chrysalids and presently emerge as perfect insects. A
few species live gregariously during the period of hibernation,
constructing for themselves a shelter of leaves woven together with
strands of silk.
_Transformation._--The larval or caterpillar stage having been
completed, and full development having been attained, the caterpillar is
transformed into a pupa, or chrysalis. Of this, the third stage in the
life of the insect, we now shall speak at length.
THE PUPA, OR CHRYSALIS
The caterpillars of many butterflies attach themselves by a button of
silk to the under surface of a branch or stone, or other projecting
surface, and are transformed into chrysalids, which are naked, and which
hang perpendicularly from the surface to which they are attached. Other
caterpillars attach themselves to surfaces by means of a button of silk
which holds the anal extremity of the chrysalis, and have, in addition,
a girdle of silk which passes around the middle of the chrysalis,
holding it in place very much as a papoose is held on the back of an
Indian squaw by a strap passed over her shoulders.
[Illustration FIG. 23.--Caterpillar of _Anosia plexippus_, undergoing
change into chrysalis: _a_, caterpillar just before rending of the skin;
_b_, chrysalis just before the cremaster, or hook, at its end is
withdrawn; _c_, chrysalis holding itself in place by the folds of the
shed skin caught between the edges of the abdominal segments, while with
the cremaster, armed with microscopic hooks, it searches for the button
of silk from which it is to hang (Riley). (Compare Fig. 24, showing
final form of the chrysalis.)]
_The Form of Chrysalids._--The forms assumed by the insect in this stage
of its being vary very greatly, though there is a general resemblance
among the different families and subfamilies, so that it is easy for
one who has studied the matter to tell approximately to what family the
form belongs, even when it is not specifically known. Chrysalids are in
most cases obscure in coloring, though a few are quite brilliant, and,
as in the case of the common milkweed butterfly (_Anosia plexippus_),
ornamented with golden-hued spots. The chrysalids of the _Nymphalidæ_,
one of the largest groups of butterflies, are all suspended. The
chrysalids of the _Papilionidæ_, or swallowtail butterflies, are held in
place by girdles, and generally are bifurcate or cleft at the upper end
(Fig. 25), and are greenish or wood-brown in color.
[Illustration FIG. 24.--Chrysalis of _Anosia plexippus_, final form
(Riley).]
[Illustration FIG. 25.--Chrysalis of _Papilio philenor_: _a_, front
view; _b_, side view, showing manner in which it is held in place by the
girdle of silk (Riley).]
[Illustration FIG. 26.--_Pieris protodice: a_, caterpillar; _b_,
chrysalis (Riley).]
A study of the structure of all chrysalids shows that within them there
is contained the immature butterfly. The segments of the body are
ensheathed in the corresponding segments of the chrysalis, and soldered
over these segments are ensheathing plates of chitinous matter under
which are the wings of the butterfly, as well as all the other organs
necessary to its existence in the airy realm upon which it enters after
emergence from the chrysalis. The practised eye of the observer is soon
able to distinguish the location of the various parts of the butterfly
in the chrysalis, and when the time for escape draws near, it is in
many cases possible to discern through the thin, yet tough and hard,
outer walls of the chrysalis the spots and colors on the wings of the
insect.
[Illustration FIG. 27.--Chrysalis of _Pieris oleracea_ (Riley.)]
_Duration of Pupal Life._--Many butterflies remain in the chrysalis
stage only for a few weeks; others hibernate in this state, and in
temperate climates a great many butterflies pass the winter as
chrysalids. Where, as is sometimes the case, there are two or three
generations or broods of a species during the year, the life of one
brood is generally longer than that of the others, because this brood is
compelled to overwinter, or hibernate. There are a number of butterflies
known in temperate North America which have three broods: a spring
brood, emerging from chrysalids which have overwintered; an early summer
brood; and a fall brood. The chrysalids in the latter two cases
generally represent only a couple of weeks at most in the life of the
insect. In tropical and semi-tropical countries many species remain in
the chrysalis form during the dry season, and emerge at the beginning of
the rains, when vegetation is refreshed and new and tender growths occur
in the forests.
[Illustration FIG. 28.--Butterfly (_Papilio asterias_) just emerging
from chrysalis.]
_The Transformation from the Chrysalis to the Imago._--The perfectly
developed insect is known technically as the _imago_. When the time of
maturity in the chrysalis state has been reached, the coverings part in
such a way as to allow of the escape of the perfect insect, which, as it
comes forth, generally carries with it some suggestion of its
caterpillar state in the lengthened abdomen, which it with apparent
difficulty trails after it until it secures a hold upon some object from
which it may depend while a process of development (which lasts
generally a few hours) takes place preparatory to flight. The imago, as
it first emerges, is provided with small, flaccid wings, which, together
with all the organs of sense such as the antennæ, require for their
complete development the injection into them of the vital fluids which,
upon first emergence, are largely contained in the cavities of the
thorax and abdomen. Hanging pendant on a projecting twig, or clinging to
the side of a rock, the insect remains fanning its wings, while by the
strong process of circulation a rapid injection of the blood into the
wings and other organs takes place, accompanied by their expansion to
normal proportions, in which they gradually attain to more or less
rigidity. Hardly anything in the range of insect life is more
interesting than this rapid development of the butterfly after its first
emergence from the chrysalis. The body is robbed of its liquid contents
in a large degree; the abdomen is shortened up; the chitinous rings
which compose its external skeleton become set and hardened; the wings
are expanded, and then the moment arrives when, on airy pinions, the
creature that has lived a worm-like life for weeks and months, or which
has been apparently sleeping the sleep of death in its cerements, soars
aloft in the air, the companion of the sunlight and the breezes.
ANATOMY OF BUTTERFLIES
The body of the butterfly consists of three parts--the head, the thorax,
and the abdomen.
[Illustration FIG. 29.--Head of milkweed butterfly, stripped of scales
and greatly magnified (after Burgess): _v_, vertex; _f_, front; _cl_,
clypeus; _lb_, labrum, or upper lip; _md_, mandibles; _a_, antennæ;
_oc_, eyes; _tk_, spiral tongue, or proboscis.]
[Illustration FIG. 30.--Cross-section of the sucking-tube of the
milkweed butterfly, to show the way in which the halves unite to form a
central canal (_c_): _tr_, tracheæ, or air-tubes; _n_, nerves; _m_,
_m^3_, muscles of one side. (Magnified 125 diameters.) (Burgess.)]
[Illustration FIG. 31.--Longitudinal section of the head of the
milkweed butterfly: _cl_, clypeus; _mx_, left maxilla, the right being
removed; _mfl_, floor of mouth; _oe_, oesophagus, or gullet; _ov_,
mouth-valve; _sd_, salivary duct; _dm_ and _fm_, dorsal and frontal
muscles, which open the sac. (Magnified 20 diameters). (Burgess.)]
_The Head._--The head is globular, its breadth generally exceeding
its length. The top is called the _vertex_; the anterior portion,
corresponding in location to the human face, is called the _front_.
Upon the sides of the head are situated the large _compound eyes_,
between which are the _antennæ_, or "feelers," as they are sometimes
called. Above the mouth is a smooth horny plate, the _clypeus_. The
_labrum_, or upper lip, is quite small. On both sides of the mouth
are rudimentary _mandibles_, which are microscopic objects. The true
suctorial apparatus is formed by the _maxillæ_, which are produced in
the form of semi-cylindrical tubes, which, being brought together and
interlocking, form a complete tube, which is known as the
_proboscis_, and which, when not in use, is curled up spirally,
looking like a watch-spring. At the upper end of the proboscis, in
the head, is a bulb-like enlargement, in the walls of which are
inserted muscles which have their origin on the inner wall of the
head. When these muscles contract, the bulb-like cavity is enlarged,
a vacuum is produced, and the fluids in the cup of the flower flow
up the proboscis and into the bulb. The bulb is also surrounded by
muscles, which, when contracting, compress it. The external opening
of the tube has a flap, or valve, which, when the bulb is compressed,
closes and causes the fluid in it to flow backward into the gullet
and the stomach. The arrangement is mechanically not unlike that in a
bulb-syringe used by physicians. The process of feeding in the case
of the butterfly is a process of pumping honeyed water out of the
flowers into the stomach. The length of the proboscis varies; at its
base and on either side are placed what are known as the maxillary
palpi, which are very small. The lower lip, or _labium_, which is
also almost obsolete in the butterflies, has on either side two
organs known as the _labial palpi_, which consist of three joints. In
the butterflies the labial palpi are generally well developed, though
in some genera they are quite small. The antennæ of butterflies are
always provided at the extremity with a club-shaped enlargement, and
because of this clubbed form of the antennæ the entire group are
known as the _Rhopalocera_, the word being compounded from the Greek
word (ῥοπαλον), which means a _club_, and the word (_κερας_) which
means a _horn_.
[Illustration FIG. 32.--Interior view of head of milkweed butterfly:
_cl_, clypeus; _cor_, cornea of the eye; _oe_, oesophagus, or gullet;
_fm_, frontal muscle; _dm_, dorsal muscles; _lm_, lateral muscles; _pm_,
muscles moving the palpus (Burgess).]
[Illustration FIG. 33.--Labial palpus of _Colias_, magnified 10
diameters.]
It will be observed from what has been said that the head in these
creatures is to a large extent the seat of the organs of sense and
alimentation. What the function of the antennæ may be is somewhat
doubtful, the opinion of scientific men being divided. The latest
researches would indicate that these organs, which have been regarded as
the organs of smell and sometimes as the organs of hearing, have
probably a compound function, possibly enabling the creature to hear,
certainly to smell, but also, perhaps, being the seat of impressions
which are not strictly like any which we receive through our senses.
[Illustration FIG. 34.--_Colias philodice_: _a_, antenna; _p_,
extremity of palpus; _pl_, prothoracic leg; _ml_, mesothoracic leg;
_hl_, metathoracic or hind leg; _t_, proboscis.]
_Thorax._--The thorax is more or less oval in form, being somewhat
flattened upon its upper surface. It is composed of three parts, or
segments, closely united, which can only be distinguished from one
another by a careful dissection. The anterior segment is known as the
prothorax, the middle segment as the mesothorax, and the after segment
as the metathorax. The legs are attached in pairs to these three
subdivisions of the thorax, the anterior pair being therefore sometimes
spoken of as the prothoracic legs, the second pair as the mesothoracic
legs, and the latter pair as the metathoracic legs (Fig. 34). On either
side of the mesothorax are attached the anterior pair of wings, over
which, at their insertion into the body, are the _tegulæ_, or lappets;
on either side of the metathorax are the posterior pair of wings. It
will be seen from what has been said that the thorax bears the organs of
locomotion. The under side of the thorax is frequently spoken of by
writers, in describing butterflies, as the _pectus_, or breast.
_The Abdomen._--The abdomen is formed normally of nine segments, and in
most butterflies is shorter than the hind wings. On the last segment
there are various appendages, which are mainly sexual in their nature.
[Illustration FIG. 35.--Leg of butterfly: _c_, coxa; _tr_, trochanter;
_f_, femur; _t_, tibia; _tar_, tarsi.]
_The Legs._--Butterflies have six legs, arranged in three pairs, as we
have already seen. Each leg consists of five parts, the first of which,
nearest the body, is called the _coxa_, with which articulates a
ring-like piece known as the _trochanter_. To this is attached the
_femur_, and united with the femur, forming an angle with it, is the
_tibia_. To the tibia is attached the _tarsus_, or foot, the last
segment of which bears the claws, which are often very minute and blunt
in the butterflies, though in moths they are sometimes strongly hooked.
The tibiæ are often armed with spines. In some groups of butterflies the
anterior pair of legs is aborted, or dwarfed, either in one or both
sexes, a fact which is useful in determining the location of species in
their systematic order.
[Illustration FIG. 36.--Magnified representation of arrangement of the
scales on the wing of a butterfly.]
[Illustration FIG. 37.--Androconia from wings of male butterflies: _a_,
_Neonympha eurytus_; _b_, _Argynnis aphrodite_; _c_, _Pieris oleracea_.]
_The Wings._--The wings of butterflies consist of a framework of horny
tubes which are in reality double, the inner tube being filled with air,
the outer tube with blood, which circulates most freely during the time
that the insect is undergoing the process of development after emergence
from the chrysalis, as has been already described. After emergence the
circulation of the blood in the outer portion of the tubes is largely,
if not altogether, suspended. These horny tubes support a broad
membrane, which is clothed in most species upon both sides with
flattened scales which are attached to the membrane in such a way that
they overlap one another like the shingles on a roof. These scales are
very beautiful objects when examined under a microscope, and there is
considerable diversity in their form as well as in their colors. The
males of many species have peculiarly shaped scales arranged in tufts
and folds, which are called androconia, and are useful in
microscopically determining species (Fig. 37). The portion of the wings
which is nearest to the thorax at the point where they are attached to
the body is called the _base_; the middle third of the wing is known as
the _median_ or _discal area_, the outer third as the _limbal area_. The
anterior margin of the wings is called the _costal margin_; the outer
edge is known as the _external margin_, the inner edge as the _inner
margin_. The shape of the wings varies very much. The tip of the front
wing is called the apex, and this may be rounded, acute, falcate
(somewhat sickle-shaped), or square. The angle formed by the outer
margin of the front wing with the inner margin is commonly known as the
_outer angle_. The corresponding angle on the hind wing is known as the
_anal angle_, and the point which corresponds to the tip or apex of the
front wing is known as the _external angle_ (Fig. 38). A knowledge of
these terms is necessary in order to understand the technical
descriptions which are given by authors.
+--------------------------------------------------------------+
| |
| EXPLANATION OF PLATE III |
| |
| Reproduced, with the kind permission of Dr. S.H. Scudder, |
| from "The Butterflies of New England," vol. iii, Plate 74. |
| |
| CATERPILLARS OF NYMPHALIDÆ |
| |
| 1. _OEneis semidea._ Penultimate stage. |
| 2. _OEneis semidea._ |
| 3. _Neonympha eurytus._ |
| 4. _OEneis semidea._ |
| 5. _Anosia plexippus._ |
| 6. _Neonympha eurytus._ |
| 7. _OEneis semidea._ Just hatched. |
| 8. _Neonympha phocion._ |
| 9. _Satyrodes canthus._ |
| 10. _Neonympha eurytus._ |
| 11. _OEneis jutta._ Just hatched. |
| 12. _Neonympha phocion._ |
| 13. _Neonympha eurytus._ Penultimate |
| stage. |
| 14. _Neonympha eurytus._ Plain and enlarged. |
| 15. _OEneis semidea._ |
| 16. _Debis portlandia._ |
| 17. _Basilarchia astyanax._ |
| 18. _Satyrus alope._ |
| 19. _Basilarchia disippus._ |
| 20. _Chlorippe clyton._ |
| 21. _Basilarchia astyanax._ |
| 22. _Basilarchia disippus._ Plain outline |
| to show the attitude sometimes |
| assumed. |
| 23. _Grapta interrogationis._ |
| 24. _Basilarchia disippus._ |
| 25. _Basilarchia astyanax._ Plain. |
| 26. _Basilarchia arthemis._ |
| 27. _Grapta interrogationis._ |
| 28. _Vanessa antiopa._ |
| 29. _Junonia coenia._ |
| 30. _Junonia coenia._ |
| 31. _Grapta progne._ |
| 32. _Grapta faunus._ |
| 33. _Grapta satyrus._ |
| 34. _Pyrameis huntera._ |
| 35. _Pyrameis atalanta._ |
| 36. _Vanessa milberti._ |
| 37. _Pyrameis cardui._ |
| 38. _Grapta comma._ |
| |
| [Illustration PLATE III.] |
+--------------------------------------------------------------+
If a wing is examined with the naked eye, or even with a lens, a clear
conception of the structure of the veins can rarely be formed. Therefore
it is generally necessary to remove from the wings the scales which
cover them, or else bleach them. The scales may be removed mechanically
by rubbing them off. They may be made transparent by the use of chemical
agents. In the case of specimens which are so valuable as to forbid a
resort to these methods, a clear knowledge of the structure of the veins
may be formed by simply moistening them with pure benzine or chloroform,
which enables the structure of the veins to be seen for a few moments.
The evaporation of these fluids is rapid, and they produce no ill effect
upon the color and texture of the wings. In the case of common species,
or in the case of such as are abundantly represented in the possession
of the collector, and the practical destruction of one or two of which
is a matter of no moment, it is easy to use the first method. The wing
should be placed between two sheets of fine writing-paper which have
been moistened by the breath at the points where the wing is laid, and
then by lightly rubbing the finger-nail or a piece of ivory, bone, or
other hard substance over the upper piece of paper, a good many of the
scales may be removed. This process may be repeated until almost all of
them have been taken off. This method is efficient in the case of many
of the small species when they are still fresh; in the case of the
larger species the scales may be removed by means of a camel's-hair
pencil such as is used by painters. The chemical method of bleaching
wings is simple and inexpensive. For this purpose the wing should be
dipped in alcohol and then placed in a vessel containing a bleaching
solution of some sort. The best agent is a solution of chloride of lime.
After the color has been removed from the wing by the action of the
chloride it should be washed in a weak solution of hydrochloric acid. It
may then be cleansed in pure water and mounted upon a piece of glass, as
microscopic slides are mounted, and thus preserved. When thus bleached
the wing is capable of being minutely studied, and all points of its
anatomy are brought clearly into view.
[Illustration FIG. 38.--Outline of wing, giving names of parts.]
[Illustration FIG. 39.--Arrangement of scales on wing of butterfly.]
The veins in both the fore and hind wings of butterflies may be divided
into simple and compound veins. In the fore wing the simple veins are
the costal, the radial, and the submedian; in the hind wing, the costal,
the subcostal, the upper and lower radial, the submedian, and the
internal are simple. The costal vein in the hind wing is, however,
generally provided near the base with a short ascending branch which is
known as the precostal vein. In addition to these simple veins there are
in the fore wing two branching veins, one immediately following the
costal, known as the subcostal, and the other preceding the submedian,
known as the median vein. The branches of these compound veins are known
as nervules. The median vein always has three nervules. The nervules of
the subcostal veins branch upwardly and outwardly toward the costal
margin and the apex of the fore wing. There are always from four to five
subcostal nervules. In the hind wing the subcostal is simple. The median
vein in the hind wing has three nervules as in the fore wing. Between
the subcostal and the median veins, toward the base in both wings, is
inclosed the cell, which may be wholly or partially open at its outer
extremity, or closed. The veinlets which close the cell at its outward
extremity are known as the discocellular veins, of which there are
normally three. From the point of union of these discocellular veins go
forth the radial veins known respectively as the upper and lower
radials, though the upper radial in many genera is emitted from the
lower margin of the subcostal.
An understanding of these terms is, however, more readily derived from a
study of the figure in which the names of these parts are indicated
(Fig. 40).
[Illustration FIG. 40.--Wing of _Anosia plexippus_, showing the names
of the veins and nervules: _C_, _C_, costal veins; _SC_, subcostal vein;
_SC_1_, etc., subcostal nervules; _UR_, upper radial; _LR_, lower
radial; _M_, median veins; _M_1_, _M_2_, _M_3_, median nervules; _SM_,
submedian veins; _I_, internal veins; _PC_, precostal nervule; _UDC_,
_MDC_, _LDC_, upper, middle, and lower discocellulars.]
Butterflies generally hold their wings erect when they are at rest, with
their two upper surfaces in proximity, the under surfaces alone
displaying their colors to the eye. Only in a few genera of the larger
butterflies, and these tropical species, with which this book does not
deal, is there an exception to this rule, save in the case of the
_Hesperiidæ_, or "skippers," in which very frequently, while the
anterior wings are folded together, the posterior wings lie in a
horizontal position.
_Internal Organs._--Thus far we have considered only the external organs
of the butterfly. The internal organs have been made the subject of
close study and research by many writers, and a volume might be
prepared upon this subject. It will, however, suffice for us to call the
attention of the student to the principal facts.
[Illustration FIG. 41.--Longitudinal section through the larva of
_Anosia plexippus_, ♂, to show the internal anatomy (the Roman numerals
indicate the thoracic, the Arabic the abdominal segments): _b_, brain;
_sog_, suboesophageal ganglion; _nc_, nervous cord; _oe_, oesophagus;
_st_, stomach; _i_, intestine; _c_, colon; _sv_, spinning-vessel of one
side; _s_, spinneret; _mv_, Malpighian vessel, of which only the
portions lying on the stomach are shown, and not the multitudinous
convolutions on the intestine; _t_, testis; _dv_, dorsal vessel; the
salivary glands are not shown. (Magnified 3 diameters.) (Burgess.)]
The muscular system finds its principal development in the thorax, which
bears the organs of locomotion. The digestive system consists of the
proboscis, which has already been described, the gullet, or oesophagus,
and the stomach, over which is a large, bladder-like vessel called the
food-reservoir, a sort of crop preceding the true stomach, which is a
cylindrical tube; the intestine is a slender tube, varying in shape in
different genera, divided into the small intestine, the colon, and the
rectum. Butterflies breathe through spiracles, little oval openings on
the sides of the segments of the body, branching from which inwardly are
the tracheæ, or bronchial tubes. The heart, which is located in the same
relative position as the spine in vertebrate animals, is a tubular
structure. The nervous system lies on the lower or ventral side of the
body, its position being exactly the reverse of that which is found in
the higher animals. It consists of nervous cords and ganglia, or
nerve-knots, in the different segments. Those in the head are more
largely developed than elsewhere, forming a rudimentary brain, the
larger portion of which consists of two enormous optic nerves. The
student who is desirous of informing himself more thoroughly and
accurately as to the internal anatomy of these insects may consult with
profit some of the treatises which are mentioned in the list of works
dealing with the subject which is given elsewhere in this book.
[Illustration FIG. 42.--Longitudinal section through the imago of
Anosia plexippus, ♀, to show the internal anatomy: _t_, tongue; _p_,
palpus; _a_, antenna; _pr_, prothorax; _mes_, mesothorax; _met_,
metathorax; _ps_, pharyngeal sac; _b_, brain; _sog_, suboesophageal
ganglion; 1-2, blended first and second ganglia of the larva; 3-4,
blended third and fourth ganglia of the larva; _l_, _l_, _l_, the three
legs; _ac_, aortal chamber; _dv_, dorsal vessel; _oe_, oesophagus; res,
reservoir for air or food; _st_, stomach; _mv_, Malpighian vessels; _i_,
intestine; _c_, colon; _r_, rectum; _cp_, copulatory pouch; _o_,
oviduct; _ag_, accessory glands; _sp_, spermatheca; _ov_, ovaries (not
fully developed); _nc_, nervous cord. (Magnified 3 diameters.)
(Burgess.)]
_Polymorphism and Dimorphism._--Species of butterflies often show great
differences in the different broods which appear. The brood which
emerges in the springtime from the chrysalis, which has passed the
winter under the snows, may differ very strikingly from the insect which
appears in the second or summer brood; and the insects of the third or
fall brood may differ again from either the spring or the summer brood.
The careful student notes these differences. Such species are called
polymorphic, that is, appearing under different forms. Some species
reveal a singular difference between the sexes, and there may be two
forms of the same sex in the same species. This is most common in the
case of the female butterfly, and where there are two forms of the
female or the male such a species is said to have dimorphic females or
males. This phenomenon is revealed in the case of the well-known Turnus
Butterfly; in the colder regions of the continent the females are yellow
banded with black, like the males, but in more southern portions of the
continent black females are quite common, and these dark females were
once thought, before the truth was known, to constitute a separate
species.
_Albinism and Melanism._--Albinos, white or light-colored forms, are
quite common among butterflies, principally among the females. On the
other hand, melanism, or a tendency to the production of dark or even
black forms, reveals itself. Melanism is rather more common in the case
of the male sex than in the female sex. The collector and student will
always endeavor, if possible, to preserve these curious _aberrations_,
as they are called. We do not yet entirely understand what are the
causes which are at work to produce these changes in the color, and all
such aberrant specimens have interest for the scientific man.
_Monstrosities._--Curious malformations, producing monstrosities,
sometimes occur among insects, as in other animals, and such malformed
specimens should likewise be preserved when found. One form of
malformation which is not altogether uncommon consists in an apparent
confusion of sexes in specimens, the wings of a male insect being
attached to the body of a female, or half of an insect being male and
half female.
_Mimicry._--One of the most singular and interesting facts in the animal
kingdom is what has been styled mimicry. Certain colors and forms are
possessed by animals which adapt them to their surroundings in such wise
that they are in a greater or less degree secured from observation and
attack. Or they possess forms and colors which cause them to approximate
in appearance other creatures, which for some reason are feared or
disliked by animals which might prey upon them, and in consequence of
this resemblance enjoy partial or entire immunity. Some butterflies, for
instance, resemble dried leaves, and as they are seated upon the twigs
of trees they wholly elude the eye. This illustrates the first form of
mimicry. Other butterflies so closely approximate in form and color
species which birds and other insects will not attack, because of the
disagreeable juices which their bodies contain, that they are shunned by
their natural enemies, in spite of the fact that they belong to groups
of insects which are ordinarily greedily devoured by birds and other
animals. A good illustration of this fact is found in the case of the
Disippus Butterfly, which belongs to a group which is not specially
protected, but is often the prey of insect-eating creatures. This
butterfly has assumed almost the exact color and markings of the
milkweed butterfly, _Anosia plexippus_, which is distasteful to birds,
and hence enjoys peculiar freedom from the attacks of enemies. Because
this adaptation of one form to another evidently serves the purpose of
defense this phenomenon has been called "protective mimicry." The reader
who is curious to know more about the subject will do well to consult
the writings of Mr. Alfred Russel Wallace and Mr. Darwin, who have
written at length upon mimicry among butterflies. There is here a field
of most interesting inquiry for the student.
_The Distribution of Butterflies._--Butterflies are found everywhere
that plant life suited to the nourishment of the caterpillars is found.
There are some species which are arctic and are found in the brief
summer of the cold North and upon the lofty summits of high mountains
which have an arctic climate. Most of them are, however, children of the
sun, and chiefly abound in the temperate and tropical regions of the
earth. While the number of species which are found in the tropics vastly
exceeds the number of species found in the temperate zone, it is
apparently true that the number of specimens of certain species is far
more numerous in temperate regions than in the tropics. Very rarely in
tropical countries are great assemblages of butterflies to be seen, such
as may be found in the summer months in the United States, swarming
around damp places, or hovering over the fields of blooming clover or
weeds. In the whole vast region extending from the Rio Grande of Texas
to the arctic circle it is doubtful whether more than seven hundred
species of butterflies are found. On the continent of Europe there are
only about four hundred and fifty species. The number of species of
butterflies and the number of species of birds in the United States are
very nearly the same.