iqo 



THE INSECT WORLD. 



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 proper place, the cater- 

 pillar has only to bring round its head to the fifth segment. 

 The thread will be drawn ft-om 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 



Fig. io8.— Caterpillars of the Cabbage Butterfly {Pietis brassiccr). 



remain for it to secure the second end of the thread agamst 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. io8). 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. 

 litde by little from this situation by bending towards the other side, | 

 and by causing its head to pass gently over the last quarter of the! 

 circle. At last the. caterpillar finds itself bound on the second side;; 

 the head rests on the thread-covered plane, and the insect fixes the! 

 second end of the thread." 



It has only to repeat the same manoeuvre as many times as there 



