STATES OF INSECTS. 209 



our caterpillars, instructed by a beneficent Creator, easily 

 perform. Their manoeuvres 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 a 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 latteYs 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 



b Plate XXIII. Fig. 1. a. 

 VOL. Ill, P 



