30 PAEASITIC COCOONS. 



common course of nature, it is accustomed to discard the 

 caterpillar and put on the chrysalis form. But Nature has, 

 in this case, been overruled (we may be certain, as always, by 

 the wise permission of her Great Master), the tiny ichneumon 

 having been employed as the agent of her defeat. 



We have happened, perhaps, to see a caterpillar, visited as 

 just described, ascend its wall or paling. In a day or two, 

 perhaps in a few hours, we see it again, still a caterpillar, and 

 alive, but reduced almost to an empty skin, while heaped 

 around it is a mass of little oval cocoons of yellow silk. By 

 some people these might be taken for the caterpillar's eggs ; 

 by others, for a specimen of its own spinning ; and they might 

 suppose, moreover, that it had worked so hard as well-nigh to 

 work itself to death ; but no such thing the yellow silken 

 cases have been spun by the little brood of parasites, which, 

 having simultaneously deserted the poor shrunken body of 

 their fosterer, have thus shrouded themselves for safe attain- 

 ment of the winged perfection which she (poor blighted pro- 

 mise of a butterfly !) is never to attain. 



One most noteworthy circumstance in the above and other 

 parasitic infestations of a similar kind, is the avoidance, by the 

 ichneumon devourers, of every vital part of the caterpillar 

 devoured, whose living juices are requisite for their support. 



Incipient moths, as well as butterflies, are continually being 

 defrauded of their winged estate through the agency of ichneu- 

 mon, and sometimes other parasites. 



