The body is shorter and thicker than it is in most butterflies, and is pointed at the tip rather than knobbed or bent downwards; the wings are less ample; the antennae are not truly knobbed, but are thicker before the actual tip, which is itself pointed and more or less bent backwards, so that the antennae are somewhat hook-shaped.
In habits as well as structure the family is markedly distinct from butterflies; the pupation is peculiar, and the name Skipper has been applied to the perfect Insects, because so many of them indulge in a brief, jerky flight, instead of the prolonged aerial courses characteristic of the higher butterflies.
There is great difference among the members of the family, and some of them possess a very high development of the powers of locomotion, with a correspondingly perfect structure of the thoracic region, so that, after inspection of these parts, we can quite believe Wallace's statement that the larger and strong-bodied kinds are remarkable for the excessive rapidity of their flight, which, indeed, he was inclined to consider surpassed that of any other Insects. "The eye cannot follow them as they dart past; and the air, forcibly divided, gives out a deep sound louder than that produced by the humming-bird itself. If power of wing and rapidity of flight could place them in that rank, they should be considered the most highly organised of butterflies." It was probably to the genera Pyrrhopyge, Erycides, etc., that Mr. Wallace alluded in the above remarks. Although the Hesperiidae are not as a rule beautifully coloured, yet many of these higher forms are most tastefully ornamented; parts of the wings, wing-fringes, and even the bodies being set with bright but agreeable colours. We mention these facts because it is a fashion to attribute a lowly organisation to the family, and to place it as ancestral to other butterflies. Some of them have crepuscular habits, but this is also the case with a variety of other Rhopalocera in the tropics.
In their early stages the Skippers—so far as at present known—depart considerably from the majority of butterflies, inasmuch as they possess in both the larval and pupal instars habits of concealment and retirement. The caterpillars have the body nearly bare, thicker in the middle, the head free, and more or less notched above. They make much greater use of silk than other butterfly-larvae do, and draw together leaves to form caves for concealment, and even make webs and galleries. Thus the habits are almost those of the Tortricid moths.
Fig. 185—Pupation of Badamia exclamationis. (After Dudgeon. J. Bombay Soc. x. 1895, p. 144). A, One side of the leaf-cradle, the other (nearest to the observer) being broken away; B, transverse section of entire cradle, a, The pupa; b, fastenings of perpendicular threads round pupa; c, cross thread retaining the leaf in cradle form; d, margins of the leaf; e, midrib of leaf.
Pupation takes place under similar conditions; and it is interesting to find that Chapman considers that the pupa in several points of structure resembles that of the small moths. Not only does the larva draw together leaves or stalks to make a shelter for the pupa, but it frequently also forms a rudimentary cocoon. These arrangements are, however, very variable, and the accounts that have been given indicate that even the same species may exhibit some amount of variation in its pupation. Scudder considers that, in the North American Skippers, the cremaster is attached to a single Y-like thread. In other cases there is a silk pad on the leaf for the cremaster to hook on. An interesting account given by Mr. Dudgeon of the pupation of a common Indian Skipper, Badamia exclamationis, shows that this Insect exercises considerable ingenuity in the structure of the puparium, and also that the arrangements it adopts facilitate one of the acts of pupation most difficult for such pupae as suspend themselves, viz. the hooking the cremasters on to the pad above them. Badamia uses a rolled-up leaf (Fig. 185); the edges of the leaf are fastened together by silk at d; from this spot there descends a thread which, when it reaches the pupa, a, forks so as to form an inverted Y, and is fastened to the leaf on either side; the two sides of the leaf are kept together by a cross thread, cc. Mr. Dudgeon was fortunate enough to observe the act of pupation, and saw that "although the anal prolegs of the larva were attached to a tuft or pad of silk in the usual way, and remained so until nearly the whole skin had been shuffled off, yet when the last segment had to be taken out, the pupa drew it entirely away from the skin and lifted it over the empty skin, and by a series of contortions similar to those made by an Insect in depositing an egg, it soon re-attached its anal segment or cremaster to the web, throwing away the cast-off skin by wriggling its body about."
Series II. Heterocera. Moths.
Although Rhopalocera—if exclusion be made of the Hesperiidae—is probably a natural group, yet this is not the case with Heterocera. The only definition that can be given of Heterocera is the practical one that all Lepidoptera that are not butterflies are Heterocera. Numerous divisions of the Heterocera have been long current, but their limits have become more and more uncertain, so that at the present time no divisions of greater value than the family command a recognition at all general. This is not really a matter of reproach, for it arises from the desire to recognise only groups that are capable of satisfactory definition.
Several attempts have recently been made to form a rough forecast of the future classification of moths. Professor Comstock, struck by some peculiarities presented by the Hepialidae, Micropterygidae (and Eriocephalidae), recently proposed to separate them from all other Lepidoptera as a sub-order Jugatae. Comstock's discrimination in making this separation met with general approval. The character on which the group Jugatae is based is, however, comparatively trivial, and its possession is not sufficient, as pointed out by Packard,[[230]] to justify the close association of Hepialidae and Micropterygidae, which, in certain important respects, are the most dissimilar of moths. The characters possessed by the two families in common may be summarised by saying that the wings and wing-bearing segments remain in a low stage of development. In nearly all other characters the two families are widely different. Packard has therefore, while accepting Comstock's separation of the families in question, proposed a different combination. He considers that Eriocephalidae should be separated from all others as "Protolepidoptera" or "Lepidoptera Laciniata," while the whole of the other Lepidoptera, comprised under the term "Lepidoptera Haustellata," are divided into Palaeolepidoptera (consisting only of Micropterygidae) and Neolepidoptera, comprising all Lepidoptera (inclusive of Hepialidae) except the Eriocephalidae and Micropterygidae. The question is rendered more difficult by the very close relations that exist between Micropterygidae and a sub-Order, Trichoptera, of Neuroptera. Dr. Chapman, by a sketch of the classification of pupae,[[231]] and Dyar, by one on larval stages,[[232]] have made contributions to the subject; but the knowledge of early stages and metamorphosis is so very imperfect that the last two memoirs can be considered only as preliminary sketches; as indeed seem to have been the wishes of the authors themselves.