LARGE CABBAGE BUTTERFLY. 185 



very abundant butterfly than we now have. In the 

 course of a few seasons, supposing no other ' preven- 

 tative check' to come into operation, the Cabbage 

 Butterfly would increase in a kind of geometrical 

 proportion ; our gardens would soon be absolutely 

 devoured and laid waste by the caterpillars ; and it 

 would scarcely be possible to walk abroad without 

 being smothered by the winged insects. So greatly 

 are we indebted to this apparently contemptible little 

 parasite, (whose operations are unheeded by all but 

 naturalists, and of whose very existence the generality 

 are perhaps scarcely aware,) for keeping down the 

 increase of an insect, which would otherwise become 

 a serious and alarming evil. 



" I may observe, that, though the Cabbage Butter- 

 flies did not come forth from the chrysalis till July 

 18th to 20th, the silken pupae of Microgaster pro- 

 duced swarms of the winged insects by the 12th, 

 ready to go forth and commence their destructive 

 operations on fresh broods of caterpillars. 



" The Cabbage Butterfly appeared to me to be 

 unusually abundant, between London and Dartford, 

 the first week in August ; I observed them even 

 hovering about the stalls and green grocer's shops in 

 the outskirts of London, attracted, no doubt, by the 

 cabbages and other vegetables exposed for sale. 



" Subsequent observation induces me to believe, 

 that I have by no means overrated the ravages of the 

 Microgaster, but that what is stated above, may be 

 considered as no more than an average example of its 

 destructive powers. The chalk cliffs at Dover abound 



