MAN S CHIEF COMPETITORS, THE INSECTS 57 



which were feeding on the woolly aphids of the alder and the 

 carrion flower. Most of these were butterflies, but one was 

 the young of a small pyralid moth. 



Many of the larger crickets, especially the mole-crickets, are 

 more or less predaceous, and some enormous grasshoppers 

 feed habitually on spiders, beetles and other insects, and even 

 larger things like mice and lizards when they can get them. 

 These giant grasshoppers are quite surprising things. The 

 first I ever saw, in Venezuela, I shot, believing it as it sprang 

 up to be a quail. The lazy walking-sticks are all plant feeders 

 normally, but large ones sometimes will catch flies with their 

 front legs, like mantises. 



The fire-flies are all predaceous, and many specialize on 

 snails, the larvae of some of these living in water on aquatic 

 snails and being the only phosphorescent creatures in fresh 

 water. Some carabids also are snail eaters; and one very 

 curious beetle, the European snail beetle, is peculiar in having 

 the female wingless and larva-Hke, resembling the glow-worms, 

 some of which are the females of certain fire-flies. 



Predaceous insects are mostly not particular in their food, 

 and often feed on other insect eaters. Many are cannibals, 

 normally, or when pressed for food. Crickets and many grass- 

 hoppers and the caterpillars of some of the lycaenid butter- 

 flies especially are potential cannibals. 



The predaceous habit passes naturally into parasitism, 

 a condition in which the younger stages of the insects live 

 within the bodies of their victims eating out their substance 

 in such a way as to avoid killing the host until they them- 

 selves are fully grown. While we may marvel at the way the 

 solitary bees build cells, sometimes elaborately lined with 

 leaves or felt or varnish, which they fill with food and furnish 

 with an egg, then tightly seal, our astonishment is greater 

 when we see how cleverly some insects have solved the prob- 

 lem of entering these cells and using the bee's stores, or the 

 body of the growing bee, as food for their own young. 



For instance the oil-beetles, blister-beetles, etc., mostly 



