The Butterfly Book A Popular Guide to a Knowledge of the Butterflies of North America

CHAPTER III

Chapter 34,005 wordsPublic domain

THE CLASSIFICATION OF BUTTERFLIES

"Winged flowers, or flying gems."

MOORE.

At the base of all truly scientific knowledge lies the principle of order. There have been some who have gone so far as to say that science is merely the orderly arrangement of facts. While such a definition is defective, it is nevertheless true that no real knowledge of any branch of science is attained until its relationship to other branches of human knowledge is learned, and until a classification of the facts of which it treats has been made. When a science treats of things, it is necessary that these things should become the subject of investigation, until at last their relation to one another, and the whole class of things to which they belong, has been discovered. Men who devote themselves to the discovery of the relation of things and to their orderly classification are known as systematists.

The great leader in this work was the immortal Linnæus, the "Father of Natural History," as he has been called. Upon the foundation laid by him in his work entitled "Systema Naturæ," or "The System of Nature," all who have followed after him have labored, and the result has been the rise of the great modern sciences of botany and zoölogy, which treat respectively of the vegetable and animal kingdoms.

_The Place of Butterflies in the Animal Kingdom._--The animal kingdom, for purposes of classification, has been subdivided into various groups known as subkingdoms. One of these subkingdoms contains those animals which, being without vertebræ, or an internal skeleton, have an external skeleton, composed of a series of horny rings, attached to which are various organs. This subkingdom is known by naturalists under the name of the _Arthropoda._ The word _Arthropoda_ is derived from the Greek language and is compounded of two words, (_αρθρον_), meaning a _joint_ and (_πους_), meaning a _foot_. The _Arthropoda_ seem at first sight to be made up of jointed rings and feet; hence the name.

The subkingdom of the _Arthropoda_ is again subdivided into six classes. These are the following:

Class I. The _Crustacea_ (Shrimps, Crabs, Water-fleas, etc.).

Class II. The _Podostomata_ (King-crabs, Trilobites [fossil], etc.).

Class III. The _Malacopoda_ (_Peripatus_, a curious genus of worm-like creatures, found in the tropics, and allied to the Myriapods in some important respects).

Class IV. The _Myriapoda_ (Centipedes, etc.).

Class V. The _Arachnida_ (Spiders, Mites, etc.).

Class VI. The _Insecta_ (Insects).

That branch of zoölogy which treats of insects is known as entomology.

The _Insecta_ have been variously subdivided by different scientific writers, but the following subdivision has much in it to commend it, and will suffice as an outline for the guidance of the advanced student.

CLASS VI. INSECTA (INSECTS PROPER)

HETEROMETABOLA

For the most part undergoing only a partial metamorphosis in the development from the egg to the imago.

ORDERS

1. _Thysanura._ Suborders: _Collembola_ (Podura, Springtails). _Symphyla_ (Scolopendrella). _Cinura_ (Bristletails, etc.).

2. _Dermatoptera_ (Earwigs).

3. _Pseudoneuroptera._ Suborders: _Mallophaga_ (Bird-lice). _Platyptera_ (Stone-flies, Termites, etc.). _Odonata_ (Dragon-flies, etc.). _Ephemerina_ (May-flies, etc.).

4. _Neuroptera_ (Corydalis, Ant-lion, Caddis-flies, etc.).

5. Orthoptera (Cockroach, Mantis, Mole-cricket, Grasshopper, Katydid, etc.).

6. _Hemiptera._ Suborders: _Parasita_ (Lice). _Sternorhyncha_ (Aphids, Mealy Bugs, etc.). _Homoptera_ (Cicada, Tree-hoppers, etc.). _Heteroptera_ (Ranatra, Belostoma, Water-spiders, Squash-bugs, Bedbugs, etc.).

7. _Coleoptera._ Suborders: _Cryptotetramera_ (Lady-birds, etc.). _Cryptopentamera_ (Leaf-beetles, Longhorns, Weevils, etc.). _Heteromera_ (Blister-beetles, Meal-beetles, etc.). _Pentamera_ (Fire-flies, Skipjacks, June-bugs, Dung-beetles, Stag-beetles, Rove-beetles, Tiger-beetles, etc.).

METABOLA

Undergoing for the most part a complete metamorphosis from egg, through larva and pupa, to imago.

ORDERS

8. _Aphaniptera_ (Fleas).

9. _Diptera._ Suborders: _Orthorhapha_ (Hessian Flies, Buffalo-gnats, Mosquitos, Crane-flies, Horse-flies). _Cyclorhapha_ (Syrphus, Bot-flies, Tsetse, House-flies, etc.).

10. _Lepidoptera._ Suborders: _Rhopalocera_ (Butterflies). _Heterocera_ (Moths).

11. _Hymenoptera._ Suborders: _Terebrantia_ (Saw-flies, Gall-wasps, Ichneumon-flies, etc.). _Aculeata_ (Ants, Cuckoo-flies, Digger-wasps, True Wasps, Bees).

It will be seen by glancing at the foregoing table that the butterflies and moths are included as suborders in the tenth group of the list, to which is applied the name _Lepidoptera_. This word, like most other scientific words, is derived from the Greek, and is compounded of the noun (_λεπις_), which signifies a _scale_, and the noun (_πτερον_), which signifies a _wing_. The butterflies and moths together constitute the order of scale-winged insects. The appropriateness of this name will no doubt be at once recognized by every reader, who, having perhaps unintentionally rubbed off some of the minute scales which clothe the wings of a butterfly, has taken the trouble to examine them under a microscope, or who has attentively read what has been said upon this subject in the first chapter of this book. By referring again to the classification which has been given, it will be noted that the last four orders in the list agree in that the creatures included within them undergo for the most part what is known as a complete metamorphosis; that is to say, they pass through four successive stages of development, existing first as eggs, then as worm-like larvæ, or caterpillars, then as pupæ, and finally as perfect, fully developed insects, gifted for the most part with the power of flight, and capable of reproducing their kind. All of this has been to some extent already elucidated in the first chapter of the present volume, but it may be well to remind the reader of these facts at this point.

A question which is frequently asked by those who are not familiar with the subject relates to the manner in which it is possible to distinguish between moths and butterflies. A partial answer can be made in the light of the habits of the two classes of lepidoptera. Butterflies are diurnal in their habits, flying between sunrise and dusk, and very rarely taking the wing at night. This habit is so universal that these insects are frequently called by entomologists "the diurnal lepidoptera," or are simply spoken of as "diurnals." It is, however, true that many species of moths are also diurnal in their habits, though the great majority of them are nocturnal, or crepuscular, that is, flying at the dusk of the evening, or in the twilight of the early morning. Upon the basis of mere habit, then, we are able only to obtain a partial clue to the distinction between the two suborders. A more definite distinction is based upon structure, and specifically upon the structure of the antennæ. Butterflies have long, thread-like antennæ, provided with a swelling at the extremity, giving them a somewhat club-shaped appearance (Fig. 76). This form of antennæ is very unusual among the moths, and only occurs in a few rare genera, found in tropical countries, which seem to represent connecting-links between the butterflies and the moths. All the true moths which are found within the limits of the United States and Canada have antennæ which are not club-shaped, but are of various other forms. Some moths have thread-like antennæ tapering to a fine point; others have feather-shaped antennæ; others still have antennæ which are prismatic in form, and provided with a little hook, or spur, at the end; and there are many modifications and variations of these forms. The club-shaped form of the antennæ of butterflies has led naturalists to call them _Rhopalocera_, as has been already explained in speaking of this subject on page 17. Moths are called _Heterocera_. The word _Heterocera_ is compounded of the Greek word (_πτερον_), meaning _other_, and the Greek word (_κερας_), meaning a _horn_. They are lepidoptera which have antennæ which are _other than club-shaped_. Besides the distinctions which exist in the matter of the form of the antennæ, there are distinctions in the veins of the wings, and in the manner of carrying them when at rest or in flight, which are quite characteristic of the two groups; but all of these things the attentive student will quickly learn for himself by observation.

_Scientific Arrangement._--Having thus cast a passing glance at the differences which exist between moths and butterflies, we take up the question of the subdivision of the butterflies into natural groups. Various systems of arranging butterflies have been suggested from time to time by learned writers, and for a knowledge of these systems the student may consult works which treat of them at length. It is sufficient for beginners, for whom this book is principally written, to observe that in modern science, for purposes of convenience, as well as from regard for essential truth, all individuals are looked upon as belonging to a _species_. A species includes all those individuals, which have a common ancestry, and are so related in form and structure as to be manifestly separable from all other similarly constituted assemblages of individuals. For instance, all the large cats having a tawny skin, and in the male a shaggy mane, constitute a species, which we call the lion; the eagles in the eastern United States, which in adult plumage have a snow-white head and neck and a white tail, constitute a species, which we know as the "white-headed" or "bald-headed" eagle. Species may then be grouped together, and those which are manifestly closely related to one another are regarded as forming a natural assemblage of species, to which we give the name of a _genus_. For example, all the large cats, such as the lion, the tiger, the puma, and the jaguar, are grouped together by naturalists, and form a genus to which is given the Latin name _Felis_, meaning _cat_. The name of the genus always comes before that of the species. Thus the tiger is spoken of scientifically as _Felis tigris_. The genera which are closely related to one another may again be assembled as _subfamilies_; and the subfamilies may be united to form _families_. For instance, all the various genera of cats form a family, which is known as the _Felidæ_, or the Cat Family. A group of families constitutes a _suborder_ or an _order_. The cats belong to the _Carnivora_, or order of flesh-eating animals.

In zoölogy family names are formed with the termination _-idæ_, and subfamily names with the termination _-inæ_.

Everything just said in regard to the classification of the higher animals applies likewise to butterflies. Let us take as an illustration the common milkweed butterfly. Linnæus for a fanciful reason gave this insect the name _Plexippus_. This is its specific name, by which it is distinguished from all other butterflies. It belongs to the genus _Anosia_. The genus _Anosia_ is one of the genera which make up the subfamily of the _Euploeinæ_. The _Euploeinæ_ belong to the great family of the _Nymphalidæ_. The _Nymphalidæ_ are a part of the suborder of the _Rhopalocera_, or true butterflies, one of the two great subdivisions of the order _Lepidoptera_, belonging to the great class _Insecta_, the highest class in the subkingdom of the _Arthropoda_. The matter may be represented in a tabular form, in the reverse order from that which has been given:

Subkingdom, _Arthropoda_. Class, _Insecta_. Order, _Lepidoptera_. Suborder, _Rhopalocera_. Family, _Nymphalidæ_. Subfamily, _Euploeinæ_. Genus, _Anosia_. Species, _Plexippus_ (Milkweed Butterfly).

_Varieties._--A still further subdivision is in some cases recognized as necessary. A species which has a wide range over an extensive territory may vary in different parts of the territory within which it is found. The butterflies of certain common European species are found also in Japan and Corea, but, as a rule, they are much larger in the latter countries than they are in Europe, and in some cases more brightly colored. Naturalists have therefore distinguished the Asiatic from the European form by giving the former what is known as a varietal name. Similar differences occur among butterflies on the continent of North America. The great yellow and black-barred swallowtail butterfly known as _Papilio turnus_ occurs from Florida to Alaska. But the specimens from Alaska are always much smaller than those from other regions, and have a very dwarfed appearance. This dwarfed form constitutes what is known as a local race, or variety, of the species. The members of a species which occur upon an island frequently differ in marked respects from specimens which occur upon the adjacent mainland. By insulation and the process of through-breeding the creature has come to acquire characteristics which separate it in a marked degree from the closely allied continental form, and yet not sufficiently to justify us in treating it as a distinct species. It represents what is known as an insular race, or variety, and we give it therefore a varietal name. Naturalists also distinguish between seasonal, dimorphic, melanic, and albino forms. Names descriptive or designatory of these forms are frequently applied to them. All of this will become plainer in the course of the study of the succeeding pages, and in the effort to classify specimens which the student will make.

_Sex._--The designation of the sex is important in the case of all well-ordered collections of zoölogical specimens. As a measure of convenience, the male is usually indicated by the sign of Mars, ♂, while the female is indicated by the sign of Venus, ♀. The inscription, "_Argynnis Diana_, ♂," therefore means that the specimen is a male of _Argynnis Diana_, and the inscription, "_Argynnis Diana_, ♀," means that the specimen is a female of the same species. These signs are invariably employed by naturalists to mark the sexes.

_The Division of Butterflies into Families._--Without attempting to go deeply into questions of classification at the present point, it will be well for us to note the subdivisions which have been made into the larger groups, known as families, and to show how butterflies belonging to one or the other of these may be distinguished from one another. There are five of these families represented within the territory of which this book takes notice. These five families are the following:

1. The NYMPHALIDÆ, or "Brush-footed Butterflies." 2. The LEMONIIDÆ, or "Metal-marks." 3. The LYCÆNIDÆ, or "Blues," "Coppers," and "Hair-streaks". 4. The PAPILIONIDÆ, or the "Swallowtails" and their allies. 5. The HESPERIIDÆ, or the "Skippers."

The NYMPHALIDÆ, the "Brush-footed Butterflies."

The butterflies of this family may be distinguished as a great class from all other butterflies by the fact that in _both sexes the first, or prothoracic, pair of legs is greatly dwarfed, useless for walking, and therefore carried folded up against the breast_. From this peculiarity they have also been called the "Four-footed Butterflies." This is the largest of all the families of the butterflies, and has been subdivided into many subfamilies. Some of the genera are composed of small species, but most of the genera are made up of medium-sized or large species. The family is geologically very ancient, and most of the fossil butterflies which have been discovered belong to it. The caterpillars are in most of the subfamilies provided with horny or fleshy projections. The chrysalids always hang suspended by the tail.

The LEMONIIDÆ, the "Metal-marks."

This family is distinguished from others by the fact that _the males have four ambulatory or walking feet, while the females have six such feet. The antennæ are relatively longer than in the Lycænidæ._ The butterflies belonging to this great group are mostly confined to the tropics of the New World, and only a few genera and species are included in the region covered by this volume. They are usually quite small, but are colored in a bright and odd manner, spots and checkered markings being very common. Many are extremely brilliant in their colors. _The caterpillars are small and contracted. Some are said to have chrysalids which are suspended; others have chrysalids girdled and attached at the anal extremity, like the Lycænidæ. The butterflies in many genera have the habit of alighting on the under side of leaves, with their wings expanded._

The LYCÆNIDÆ, the "Gossamer-winged Butterflies."

This great family comprises the butterflies which are familiarly known as the "hair-streaks," the "blues," and the "coppers." _The males have four and the females six walking feet. The caterpillars are small, short, and slug-shaped. The chrysalids are provided with a girdle, are attached at the end of the abdomen, and lie closely appressed to the surface upon which they have undergone transformation._ Blue is a very common color in this family, which includes some of the gayest of the small forms which are found in the butterfly world. _In alighting they always carry their wings folded together and upright._

The PAPILIONIDÆ, the "Swallowtails" and their allies.

These butterflies _have six walking feet in both sexes. The caterpillars are elongate, and in some genera provided with osmateria, or protrusive organs secreting a powerful and disagreeable odor. The chrysalids are elongate, attached at the anal extremity, and held in place by a girdle of silk, but not closely appressed to the surface upon which they have undergone transformation._

The HESPERIIDÆ, or the "Skippers."

They are generally _small in size, with stout bodies, very quick and powerful in fight. They have six walking feet in both sexes. The tibiæ of the hind feet, with few exceptions, have spurs. The caterpillars are cylindrical, smooth, tapering forward and backward from the middle, and generally having large globular heads. For the most part they undergo transformation into chrysalids which have a girdle and an anal hook, or cremaster, in a loose cocoon, composed of a few threads of silk_, and thus approximate the moths in their habits. The genus _Megathymus_ has the curious habit of burrowing in its larval stage in the underground stems of the yucca.

To one or the other of these five families all the butterflies, numbering about six hundred and fifty species, which are found from the Rio Grande of Texas to the arctic circle, can be referred.

_Scientific Names._--From what has been said it is plain to the reader that the student of this delightful branch of science is certain to be called upon to use some rather long and, at first sight, uncouth words in the pursuit of the subject. But experience, that best of teachers, will soon enable him to master any little difficulties which may arise from this source, and he will come finally to recognize how useful these terms are in designating distinctions which exist, but which are often wholly overlooked by the uneducated and unobservant. It is not, however, necessary that the student should at the outset attempt to tax his memory with all of the long scientific names which he encounters in this and similar books. The late Dr. Horn of Philadelphia, who was justly regarded, during the latter years of his life, as the most eminent student of the _Coleoptera_, or beetles, of North America, once said to the writer that he made it a religious duty not to try to remember all the long scientific names belonging to the thousands of species in his collection, but was content to have them attached to the pins holding the specimens in his cabinets, where he could easily refer to them. The student who is engaged in collecting and studying butterflies will very soon come, almost without effort, to know their names, but it is not a sin to forget them.

In writing about butterflies it is quite customary to abbreviate the generic name by giving merely its initial. Thus in writing about the milkweed butterfly, _Anosia plexippus_, the naturalist will designate it as "_A. plexippus_." To the specific name he will also attach the name of the man who gave this specific name to the insect. As Linnæus was the first to name this insect, it is proper to add his name, when writing of it, or to add an abbreviation of his name, as follows: "_A. plexippus_, Linnæus," or "Linn." In speaking about butterflies it is quite common to omit the generic name altogether and to use only the specific name. Thus after returning in the evening from a collecting-trip, I might say, "I was quite successful to-day. I took twenty _Aphrodites_, four _Myrinas_, and two specimens of _Atlantis_." In this case there could be no misunderstanding of my meaning. I took specimens of three species of the genus _Argynnis--A. aphrodite_, _A. myrina_, and _A. atlantis_; but it is quite enough to designate them by the specific names, without reference to their generic classification.

_Synonyms._--It is a law among scientific men that the name first given to an animal or plant shall be its name and shall have priority over all other names. Now, it has happened not infrequently that an author, not knowing that a species has been described already, has redescribed it under another name. Such a name applied a second time to a species already described is called a _synonym_, and may be published after the true name. Sometimes species have had a dozen or more different names applied to them by different writers, but all such names rank as synonyms according to the law of priority.

_Popular Names._--Common English names for butterflies are much in vogue in England and Scotland, and there is no reason why English names should not be given to butterflies, as well as to birds and to plants. In the following pages this has been done to a great extent. I have used the names coined by Dr. S.H. Scudder and by others, so far as possible, and have in other cases been forced myself to coin names which seemed to be appropriate, in the hope that they may come ultimately to be widely used. The trouble is that ordinary people do not take pains to observe and note the distinctions which exist among the lower animals. The vocabulary of the common farmer, or even of the ordinary professional man, is bare of terms to point out correctly the different things which come under the eye. All insects are "bugs" to the vulgar, and even the airy butterfly, creature of grace and light, is put into the same category with roaches and fleas. Apropos of the tendency to classify as "bugs" all things which creep and are small, it may be worth while to recall the story, which Frank Buckland tells in his "Log-book of a Fisherman and Naturalist," of an adventure which he had, when a school-boy, at the booking-office of the London, Chatham, and Dover Railway Company in Dover. He had been for a short trip to Paris, and had bought a monkey and a tortoise. Upon his return from sunny France, as he was getting his ticket up to London, Jocko stuck his head out of the bag in which his owner was carrying him. The ticket-agent looked down and said, "You will pay half-fare for him." "How is that?" exclaimed young Buckland. "Well, we charge half-fare for dogs." "But this is not a dog," replied the indignant lad; "this is a monkey." "Makes no difference," was the answer; "you must pay half-fare for him." Reluctantly the silver was laid upon the counter. Then, thrusting his hands into the pocket of his greatcoat, Buckland drew forth the tortoise, and, laying it down, asked, "How much do you charge for this?" The ancient receiver of fares furbished his spectacles, adjusted them to his nose, took a long look, and replied, "We don't charge nothin' for them; them 's insects." It is to be hoped that the reader of this book will in the end have a clearer view of facts as to the classification of animals than was possessed by the ticket-agent at Dover.