470 



NATURAL HISTORY OF ARTHROPODS. 



only at twilight. The colors of the butterflies are generally brighter and more 

 showy than those of the moths, though even this can by no means be taken as 

 a rule, the magnificent ornamentation of such tropical forms as Urania rhiphceus, 

 and many of the Indian and African GlaucopidaB, being as grand and striking as 

 any that can be presented by the butterflies themselves. But with all these appar- 

 ent contradictions, and although some of the lower families of the Diurnals (e. y., 

 the Hesperidae) closely approach the moths, while certain moths (e. g., Castnia, Syne- 

 mon, etc.) may readily, until their habits and life history are studied, be mistaken for 

 butterflies. The separation can always be made by the practised eye ; and it will there- 

 fore be sufficient for our present purpose to call brief attention to these associations of 

 structure, and, without entering more deeply into the subject, to state that the Diurnal 

 Lepidoptera are restricted to those genera which, in addition to the characters men- 

 tioned above, have the wings always elevated in repose, a habit which obtains with 

 none of the moths, though it is true that many, though not all Hesperians, rest with 

 the fore pair erect, the hinder being spread out flatly upon the supporting surface. 

 Bearing these facts in mind, and remembering that nature delights in seeming anoma- 

 lies, and that her creations, as they appear to us now, can hardly be dealt with in a 

 direct line of relationship, we shall readily understand the creatures with which we 

 have now to deal. 



The earliest stage of the butterfly, as of all insects, is the egg. These are laid 



with remarkable instinct by the parent, in- 

 serted either on or near the plant which is to 

 become the future food of the larva, and are 

 usually deposited singly, or, at least, very rarely 

 in masses. They are of various shapes, mostly, 

 however, inclining to spherical or cone-shape, 

 with a flattened base ; are very seldom quite 

 smooth, but often marked with ridges or gran- 

 ulations, giving a lace-like appearance to the 

 surface. Some have raised points or cones, 

 and a few species bear small and insignificant 

 spines. The period occupied in the egg state 

 varies considerably, some species producing 

 the larva in five or six days, while others remain nearly a month, and not a few pass 

 entirely through the winter in that condition. 



The larvae begin to feed immediately on their exclusion from the egg, and rapidly 

 increase in growth. They cast their skins four, five, or, according to some observers, 

 in a few species, not less than six or even eight times, each moult producing a greater 

 or less change in the appearance of the caterpillar, and adding greatly to its size. 

 The body is composed of twelve segments exclusive of the head, the three anterior of 

 which bear the true legs, and the sixth, seventh, eighth, and ninth the abdominal or 

 prolegs, the anal segment being provided with claspers or modified legs, making in all 

 eight pairs, the fourth, fifth, tenth, and eleventh segments being devoid of these 

 organs. The body is furnished with various forms and arrangements of hairs, spines, 

 and tubercles, and the difference in color and in the disposal of the markings affords 

 a good guide in distinguishing many closely allied species. In the Papilonidae the 

 caterpillar is furnished on the upper and forward part of the second segment with a 

 pair of retractile horns which, in many species, secrete a strongly smelling fluid, 



FIG. 594. Lepidopterous eggs, enlarged. 



