10 INSECT ARTIZANS AND THEIR WORK 



is repeated, so that the chrysaHs reposes behind 

 two puzzle-doors which oppose no obstruction to 

 the moth. 



In a North American species of Silkworm {Platy- 

 samia cecropia) this type of cocoon is improved 

 upon. There are in fact two cocoons, one inside 

 the other, with a packing of loosely spun threads 

 between the two walls, which keeps the inner cocoon 

 in place, and must protect the contained chrysalis 

 from great changes of temperature. But this 

 arrangement, though admirable for the chrysalis 

 and the moth, is not appreciated by those who 

 would convert its filaments into woven tissues. 

 The open upper end of the cocoon makes it a 

 difficult matter to unwind the silk, and so it does 

 not appear to have a high commercial value, though 

 it is said to have been successfully woven into 

 stockings. As the cocoon is three inches or more 

 in length and nearly an inch and a half broad, one 

 would expect that the extra quantity of silk would 

 make up for this defect. In California, however, 

 a smaller species of the same family is reared for 

 the sake of its silk much as the Silkworm of the 

 Old World is. 



The Cecropia Moth, as may be supposed from 

 the dimensions of its cocoon, is a large insect. When 

 the moth spreads its beautifully ornamented wings, 

 the distance between the tips of the forewings is 

 about six inches ; and the caterpillar that spins 

 the big cocoon is four inches long and nearly an 

 inch in thickness. It is gloriously coloured with a 



