INSECTS 



237 



cutting off the food sup- 

 ply of caterpillars in cap- 

 tivity as they will usually, 

 in such event, at once 

 begin the spinning of a 

 cocoon. 



If the cocoon is cut 

 open lengthwise, the dor- 

 mant insect or chrj'salis 

 will be found together 

 with the cast-off skin of 

 the caterpillar which spun 

 the case. You can easily 

 make out the parts of the 

 adult moth, the antennae 

 and wings folded close to 

 the body. Notice how 

 the head and thorax are 

 crowded together. Find 

 the weak spot in the 

 cocoon through which the 

 adult makes its escape. 

 Draw the pupa in the 

 cocoon, and label all its 

 parts. 



Silkworms. — The 

 American silkworm 

 (Telea polyphemus) is 

 another well-known 



Life history of the Cecropia moth. Above, the adult; the 

 larva (caterpillar) in center; the pupal case to right, 

 below; the same cut open at left, below. From photo- 

 graph loaned by the American Museum of Natural 

 History. 



moth. The cocoons, 

 made in part out of the leaves of the elm, oak, or maple, fall to 

 the ground when the leaves drop, and hence are not so easily 

 found as those of the Cecropia. This moth is a near relative 

 of the Chinese silkworm, and its silk might be used with success 



were it not for the high 

 rate of labor in this coun- 

 try. The Chinese silk- 

 worm is now raised with 

 ease in southern California, 

 China, Japan, Italy, and 

 France, because of cheap 

 labor, are still the most 

 successful silk-raising 

 _ , ^ , ,. ^ , . „. , , . countries. It is estimated 



Folyphemus, one half natural size. Jrhotograpneu 



by Davison. that it takes the silk from 



