STATES OF INSECTS. 231 



strap-shaped pieces of the fine upper skin, or epidermis 

 of the twig upon which it rests, regularly fastened to each 

 other in a longitudinal direction with very slender silken 

 cords. But the mode of its construction is even more 

 remarkable than the substance of which it is fabricated. 

 The caterpillar's first process is to form its slips of bark 

 into two fiat triangular wing-like pieces, projecting oppo- 

 site to each other from each side of the twig, somewhat 

 like the feathers of an arrow. It does not, perhaps, re- 

 quire any great degree of intelligence in a larva to give 

 its cocoon the usual oval form, when it begins to arrange 

 its materials in that shape from the very first, and round 

 so good a mould as its own bent body; but we surely must 

 admit that it is a task to which no stupid artist would be 

 competent, to form first a multitude of strap-shaped la- 

 minae into two triangular plates, and then to bend these 

 plates into a case resembling the longitudinal section of a 

 cone, with an elliptical and protuberant base, — the figure 

 which the cocoon of this insect assumes. All the minu- 

 tiae of the manoeuvres which it employs in this nice ope- 

 ration could not be comprehended without a more diffuse 

 explanation than I have here room to give : suffice it to 

 say, that the caterpillar fastens silken lines to each exterior 

 opposite and longer side of the laminae, and by applying 

 all the weight of its body forces them to bend and ap- 

 proach each other, in which position it secures them by 

 other shorter lines. It next repeats the same process 

 with the upper and shorter sides of the plates ; which 

 when joined form the base of the cocoon. Both these 

 tasks are accomplished in less than an hour, and the seams 

 are so nicely joined as to be imperceptible. A fine inner 

 tapestry of silk, covering all the asperities of the exterior 



