230 STATES GF INSEcIS. ( Larva.) 
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 flat 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 laminee 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 minutize of the manceuvres which it employs in this 
nice operation 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 approach 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 co- 
coon. 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 walls, concludes its 
