Scavengers— Insects of Prey 305 



of the Blowfly to leave her eggs in flesh is too well- 

 known, and so quickly do such insects multiply when 

 the food-supply of their grubs is abundant, as to justify 

 the oft-quoted saying that three flies can devour the 

 carcase of a horse more quickly than can a lion. The 

 Egyptian sacred beetle carefully prepares a ball of 

 dung which may serve as a food-supply for her grubs ; 

 while the Burying-beetles, with similar intent, labori- 

 ously inter the bodies of small animals whereon they 

 have laid their eggs. 



Insects of Prey. — As among mammals and birds 

 so among Insects ; a large number live by preying on 

 their weaker, vegetable-feeding relations. Plant-lice 

 and Scale-insects, which often swarm over plants, 

 sucking sap from stalks and leaves, are greedily 

 devoured by Ladybird-beetles and their grubs (fig. 

 116) as well as by the grubs of Lacewing and Golden- 

 eye flies. The latter are covered with tubercles and 

 spines whereto adhere the dried-up skins of the plant- 

 lice. Thus clothed with the remains of its victims 

 the lacewing-grub creeps unobserved on its prey. 

 The most typical of the carnivorous insects — the 

 Tiger-beetles and the Dragon-flies for example — catch 

 their prey by open chase, the beetles running it down, 

 the dragon-flies pursuing it on the wing. Wherever 

 the vegetable-feeders make their way they find them- 

 selves hunted by the flesh-eaters. The root-feeding 

 grubs fall a prey to the grubs of the Ground-beetles, 

 while the tunnels of the bark-borers are inhabited by 

 various Rove and other beetles which, together with 

 their grubs, devour the wood-eating larvae. Nor do 

 the carnivorous insects prey only on members of their 

 own class. They often attack earthworms, slugs and 

 snails ; and many literally " fly at higher game." The 

 Gadflies which pierce the skin of cattle and horses 

 and suck their blood, the Breeze-flies and Mosquitoes 



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