218 HOSTILITIES OF ANIMALS. 



in the bodies of caterpillars. From these eggs proceed small 

 maggots, which gradually devour the vitals of the animal in 

 which they reside. When about to be transformed into 

 chrysalids, they pierce the skin of the caterpillar, spin their 

 pods, and remain on the empty skin till they assume the form 

 of flies, and escape into the air. Every person must recollect 

 to have seen the colewort, or cabbage caterpillar, stuck upon 

 old walls, or the window of country cottages, totally covered 

 with these chrysalids, which have the form of small maggots, 

 and are of a fine yellow color. One of the most formidable 

 enemies of the caterpillar is a black worm, with six crusta- 

 ceous legs. It is as long, and thicker than an ordinary-sized 

 caterpillar. In the fore part of the head it has two curved 

 pincers, with which it quickly pierces the belly of a cater- 

 pillar, and never qfiits the prey till it is entirely devoured. 

 The largest caterpillar is not sufficient to nourish this worm 

 for a single day ; for it daily kills and eats several of them. 

 These gluttonous worms, when gorged with food, become 

 inactive and almost motionless. When in this satiated con- 

 dition, young worms of the same species attack and devour 

 them. Of all trees, the oak, perhaps, nourishes the greatest 

 number of different caterpillars, as well as of different insects. 

 Amongst others, the oak is inhabited by a large and beautiful 

 beetle. This beetle frequents the oaks, probably because 

 that tree is inhabited by the greatest number of caterpillars. 

 It marches from branch to branch, and, when disposed for 

 food, attacks and devours the first caterpillar that comes in 

 its way. 



The pucerons, vine-fretters, or plant-lice, are very injurious 

 to trees and vegetables of almost every kind. Their species 

 are so numerous, and all of them endowed with such a 

 wonderful fertility, that we should expect to see the leaves, 

 the branches, and the stems of every plant totally covered 

 with them. But this astonishing fecundity, and the devasta- 

 tion these small insects would unavoidably produce among 

 the vegetable tribes, is checked by numberless enemies. 

 Myriads of insects of different classes, of different genera, 

 and of different species, seem to be produced for no other 

 purpose but to devour the pucerons. Some of these insects 

 are so voracious, that, notwithstanding the extreme prolific 

 powers of the pucerons, we have reason to be surprised that 

 their species are not entirely annihilated. On every leaf in- 

 habited by the puceron we find worms of different kinds. 

 These worms feed not upon the leaves, but upon the pucerons, 



