208 STATES OF INSECTS. (Larva.) 
perform. Their manceuvres I shall now endeavour to 
explain. 
When the caterpillar has selected the under-side of 
the leaf or other object to which it purposes suspending 
itself, its first process is to spin upon it a little hillock of 
silk consisting of numerous loosely interwoven threads ; 
it then bends its body so as to insinuate the anal pair of 
prolegs amongst these threads, in which, by a slight ex- 
ertion, the little crochets which surround them? become 
so strongly entangled as to support its weight with ease. 
It now suffers the anterior part of the body to fall down, 
and it hangs perpendicularly from its silken support with 
its head downwards. In this position it remains often for 
twenty-four hours, at intervals alternately contracting and 
dilating itself. At length the skin is seen to split on the 
back near the head, and a portion of the pupa appears, 
which by repeated swellings acts like a wedge, and ra- 
pidly extends the slit towards the tail. By the continu- 
ance of these alternate contractions and dilatations of the 
conical pupa, the skin of the caterpillar is at last collected 
in folds near the tail, like a stocking which we roll upon 
the ancle before withdrawing it from the foot. But now 
comes the important operation. The pupa, being much 
shorter than the caterpillar, is as yet at some distance 
from the silken hillock on which it is to be fastened; it 
is supported merely by the unsplit terminal portion of 
the latter’s skin. How shall it disengage itself from this 
remnant of its case, and be suspended in the air while it 
climbs up to take its place? Without arms or legs to 
4 Prate XXIII. Fic. 1. a. 
