126 HYMENOPTERA. 



au excessively small abdomen, which appears to spring 

 from the upper surface of the thorax, instead of from 

 the apex, the usual point of attachment. 



The family of the Ichneumonidce is very numerous, 

 and contains insects both large and excessively minute. 

 They are all parasitic on other insects, and in many 

 cases are eminently useful, as active agents in the 

 destruction of the numerous pests of the garden and 

 farm. The name of Ichneumon, originally given to 

 the carnivorous animal (Herpestes) of Egypt, because it 

 " tracked" or hunted afar the eggs of the crocodile, 

 became applied to the Hymenopterous insect, from its 

 habit of hunting for caterpillars, plant-lice, etc. These 

 insects are distinguished by having the abdomen 

 attached to the thorax at its hinder extremity, and 

 between the base of the hind-legs, and often by a 

 pedicel; the antennae are long and elegant; the ovi- 

 positor is in some species external and of great length, 

 in others it is short and concealed within the abdomen ; 

 these structural differences intimate a difference of 

 habit, for while some species deposit their eggs upon 

 exposed larvne, others guided by some mysterious in- 

 stinct, discover the habitat of some concealed grub, and 

 by means of their long sting-like ovipositors, succeed 

 in piercing through the concealing substance, and 

 lodging their eggs within the body of their victim. 

 The little Gall-fly grub may fancy itself suug and safe 

 within the large oak-apple, but the Ichneumon fly can 

 reach him ; neitlier is the wild bee secure within its 

 cell, nor the beetle in its wooden retreat within the 

 branch of some forest tree. There is scarcely a tribe 

 of insects which is not subject to the attacks of these 



