294 PARASITIC COCOONS. 



itself, perhaps in July or August, to the sheltering coping 

 of a garden wall, or cross-bar of a paling; places where, in 

 the common course of nature, it is accustomed to discard the 

 caterpillar and put on the chrysalis form. 



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 caterpillars' 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. 



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 cater- 

 pillar 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 ich- 

 neumon, and sometimes other parasites. 



During last August, we had six of the golden chrysalides 

 of the little tortoise-shell butterfly all suspended to a cluster of 

 nettles which we had planted in a flower-pot for the provision 

 of their caterpillars. From two of the number appeared duly, 

 in all their bright array of black and scarlet, blue and gold, 

 the insects to be naturally expected ; from the third issued 

 a brood of small ichneumons. Of the fourth, fifth, and sixth, 

 the " gold coats " assumed a questionable blackness, and being 

 hence led to examine how they might be filled, we found, 

 instead of the wrinkled wings and folded members of butterfly 

 occupants, three little brown barrels within each, which we 

 presently recognized for the pupa? of two-winged flies; and 

 from these accordingly came forth nine as ordinary-looking 



