154 THE INSECT WORLD. 
belonging to the first pair of membranous legs. Our caterpillar 
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 “ Mémoires 
pour |’Histoire des Insectes,” “must pass over the caterpiliar’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 






Fig. 108.—Caterpillars of the Cabbage Butterfly (Pieris brassicae). 
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 secure 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 out- 
line 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 
