CARNIVOROUS INSECTS 185 



animal matter. It is said that the dread of them is upon 

 every living tiling. Nevertheless, they do good service 

 as scavengers ; and when, as is often the case, they visit 

 the dwellings of mankind, they drive forth or destroy 

 vermin of all kinds. 



Most wasps, whether solitary or social, are largely 

 predatory; but as their hunting exploits are chiefly 

 enacted for the benefit of their offspring, they will be 

 more fittingly dealt with when we consider the insect in 

 its parental guise. This applies also to ichneumons, and 

 to many two-winged flies, which — themselves free and 

 independent beings — prepare the way for their young to 

 live as parasites. Certain Diptera, however, are pre- 

 daceous in the adult state, the most notable being the 

 robber-flies {Asilidcv) whose larvae feed inoffensively in 

 damp earth. " These flies " (says Dr. Fitch) " are inhuman 

 murderers. They are savages of the insect world, putting 

 their captives to death with merciless cruelty. Their large 

 eyes, divided into a multitude of facets, probably give 

 them the most acute and accurate vision for espying and 

 seizing their prey ; and their long, stout legs, their bearded 

 and bristly heads, their whole aspect indicates them to be 

 of a predatory and ferocious character. Like the hawk, 

 they swoop upon their prey, and grasping it securely be- 

 tween their fore-legs they violently bear it away. " Robber- 

 flies pounce upon almost any flying insect that they are 

 strong enough to master, including wasps and bees ; nor do 

 they spare their own kind. It is even said that the males 

 are frequently seized and eaten by their more robust mates. 

 Many of the species are endowed with a close mimetic 

 resemblance to stinging insects ; and it has been suggested 

 that this likeness may assist them in their murderous 

 enterprises by enabling them to approach their Hymenop- 

 terous prey without arousing suspicion. But this theory 



