154 



THE INSECT WOELD. 



legs belonging to the first pair of membranous legs. Our cater- 

 pillar begins by fixing on this point a thread, which is the first 

 of those that are intended to tie it up securely. 



" This thread," says the illustrious author of the " Memoires 

 pour mistoire des Insectes," "must pass over the caterpillar's 

 body, and be attached by its other end near the leg corresponding 

 to that near which the first end was fastened. To spin the 

 thread the proper length, and at the same time to fix it in its 



Kig. 108. Caterpillars of the Cabbage Butterfly (Pieris brassica?). 



proper place, the caterpillar has only to bring round its head to 

 the fifth segment. The thread will be drawn from the spinning 

 apparatus as the head advances over half the circumference of 

 the circle which it has to describe ; and when it has described this, 

 there will only remain for it to stick fast the second end of the 

 thread against the support. Thus the head, which was at first placed 

 against one of the legs, advances little by little on the outline 

 of the fifth ring as far as to its middle (Fig. 108). It is the 

 facility the caterpillar has of reversing its body that enables it to 

 make its head perform this journey ; in proportion as it moves 

 it over the circumference of the ring, it twists its body. And at 

 last, when it has brought it over the top of the segment, its body is 

 exactly folded in two ; it draws it little by little from this situation 

 by bending towards the other side, and by causing its head to pass 



