86 THOSE OTHER ANIMALS. 



threads, through which their insect foes cannot break, while 

 even birds seem to hold it in high respect. 



The mission of the caterpillar may be considered as two- 

 fold : he has to reach the chrysalis stage, from which he 

 will emerge as a butterfly or moth, and then perpetuate his 

 species ; and he is an admirable machine for the conversion 

 of vegetable matter into a form in which it can be digested 

 and relished by birds. He stands to the feathered world, 

 indeed, in exactly the same position that the ox and the 

 sheep occupy in relation to man. Although partial to seeds 

 and fruits, birds are not vegetarians in the broad sense of 

 the term, and many would starve had they nothing but 

 leaves, whether of the rose or the cabbage, to devour ; the 

 caterpillar then comes to the rescue, and forms the inter- 

 mediary link. He possesses an appetite of extraordinary 

 voracity, and in the course of his not very long life eats 

 many hundred times his own weight of vegetables, and 

 converts them into a rich and luscious food for the birds. 

 It may be said that, in some respects at least, the instincts 

 of caterpillars must be defective, or, knowing that their 

 plumpness is their danger, they would eat less. This is no 

 doubt true, but as it is true also of sheep and bullocks, it 

 can hardly be made the subject of reproach to the cater- 

 pillar. 



But, after all, vast as is the number of caterpillars who 

 go to feed the birds, it cannot be said that birds are by any 

 means their chief enemy. Their great foe and relentless 

 exterminator is the ichneumon, against whom none of their 

 cunning devices of concealment avail, for he can discover 

 them unerringly in their inmost lurking-places. The ichneu- 

 mon varies in size as greatly as does the caterpillar himself. 



