HYMENOPTERA. 343 



the Cuckoo-flies, the great genus Ichneumon* of 

 Linnaeus. Their instincts constitute them one of 

 the greatest auxiliaries to man, as they keep down 

 to an amazing extent the increase of other Insects, 

 which would else soon produce famine by devour- 

 ing the labours of agriculture. They do not, how- 

 ever, attack the perfect insects, but the larva ; and 

 chiefly those of Butterflies and Moths. The fe- 

 male Ichneumon) which may often be seen peep- 

 ing about bushes in search of her prey, pierces the 

 flesh of a caterpillar with her slender egg-tube, 

 and deposits there an egg ; occasionally, this is re- 

 peated many times, and many eggs are lodged within 

 the body. The caterpillar seems to experience no 

 inconvenience except the momentary pain of the 

 puncture, but goes on feeding as before. In pro- 

 cess of time, however, the egg hatches, and the grub 

 finds abundant food in the fat of the caterpillar, 

 on which it feeds, without touching the vital parts, 

 until it is full grown. The caterpillar is generally 

 too much enfeebled to undergo its change into pupa, 

 but dies ; the grub either perfecting its condition 

 within the body, and emerging a perfect fly, or else, 

 as in the case of the species (Microg aster -\ Glome- 

 ratus) that inhabits in numbers the caterpillar of 

 the White Cabbage Butterfly, (Pontia Brassica,) eat- 

 ing a hole through the skin, and spinning its little 

 yellow cocoon with those of its fellows about the 



* The Greek name of an animal that destroyed the Crocodile in the egg. 

 f M/x^oj, mikros, little, and yuffrfy, gaster, the belly. 



