Insects of Prey — Parasites 307 



their grubs when hatched may devour it. The Social 

 Wasps kill small insects, breaking them into pieces 

 capable of being eaten by their grubs, which they 

 feed throughout the course of their growth as birds 

 feed their young. 



Parasites. — The habits of the Ichneumon -flies 

 and related Hymenopterous families introduce another 

 means of livelihood. The female lays her eggs in the 

 body of some insect — usually a caterpillar — piercing 

 the skin with 

 her ovipositor. 

 The grubs, 

 when hatched, 

 f e e d within 

 the body of 

 their " host,"ftd 

 avoiding the 

 vital parts so 

 that the cater- 

 pillar may 

 remain alive 

 and their 

 f o o d-s u p p 1 y 

 not be cut off. 

 Even the 

 wood-boring 

 grubs are not 

 safe from the attacks of Ichneumons, many of which 

 have ovipositors long and strong enough to pierce 

 through the wood and reach the larva burrowing 

 within. These Ichneumon-grubs, being devourers of 

 living insects in or on whose bodies they pass the 

 whole of their lives, are usually regarded as parasites, 

 though their method of feeding is rather transitional 

 between a normal carnivorous habit and true parasitism. 

 Instances are known of the grubs of one species of 



;. 165. — a. Sheep-tick, I\1 ilo/'hagiis crz'imis {.XJinn.),, 

 magnified 7 times ; b. puparium, magnified. 

 From Osborn, Bull. 5 (n.s.), Div. Ent. U..S. 

 Dept. Agr. 



