LEPIDOPTERA. 



157 



This was the beginning of a cocoon. Each triangular blade was 

 composed of a great number of small, thin, rectangular plates, taken 



I 



ii 



Figs. 122, 123.— Cocoon of Pyralis corticalis (magnified, proper size § inch). 



from the bark of the twig. The caterpillar detached with its jaws a 

 small band of bark, and fitted it on, and adjusted it with admirable 

 precision against the edge already formed. It then fixed it securely 



