THE CECROPIA MOTH 145 



green coloring mimics its surroundings closely. It is all but invisible 

 at a distance, even to the human eye. To a bird, it is probably en- 

 tirely so. When a bird comes upon one of these caterpillars at close 

 range, it knows only too well that it is on dangerous ground, for the 

 gaudy color of cecropia's spines actually serve to inform it that the 

 creature contains poisonous ingredients and is not fit to eat. 



When the larva is ready for its cocoon, it crawls to some convenient 

 spot in a corner, or under a piece of old lumber, usually in a more 

 or less protected position, but never so that the moth would be ham- 

 pered when hatching. When it reaches its final destination, from 

 which the cocoon is to be spun, the larva becomes absolutely motion- 

 less, remaining so for many hours. This condition probably has 

 something to do with the formation of the silk in the creature's glands. 

 No doubt it is necessary for a certain period to elapse before the 

 silk will flow freely enough to be spun into a cocoon. 



When this period is over, the larva will suddenly be seen to stretch 

 its head out as far as it can reach, then touching the object with 

 which it comes in contact, it fastens the pure silvery silk to it. Now 

 the insect turns its entire body with the exception of its last segment. 

 Then, throwing its head back over the body, it pulls a thin silken 

 thread from its mouth, fastening it again to the farthest point that 

 can be reached at the back. This operation is repeated hundreds of 

 times, in every direction, until at length the larva has completely cov- 

 ered itself. A second cocoon, much smaller than the first and more 

 compactly constructed, is then spun within the first. The silk leaves 

 the insect's mouth in a silvery liquid, hardening only when it comes 

 in contact with the air. This turns to a deep reddish-brown about 

 five days after the cocoon has been completed. 



Inside the cocoon, the larva shrinks to about one-third its normal 

 size. Then the skin begins to dry and becomes very brittle, finally 

 splitting down the back and thus changing the larva to a pupa, or 



