2l8 ENTOMOLOGY 



be sure, are remarkably dominant among insects, but their parasitic 

 adaptations are limited for the most part to the larval stage and the 

 adults may be said to be as free for new adaptations as any other 

 Hymenoptera. 



Scavenger and Carrion Insects. Not a few families of Diptera 

 and Coleoptera derive their food from dead animal matter. The aquatic 

 families Dytiscidae and Gyrinidae are largely scavengers. Among terres- 

 trial forms, Silphidae feed on dead animals of all kinds; the burying 

 beetles (Necrophorus), working in pairs, undermine and bury the bodies 

 of birds, frogs and other small animals, and lay their eggs in the carcasses; 

 Histeridae and Staphylinidae are carrion beetles, and Dermestidae attack 

 dried animal matter of almost every description, their depredations upon 

 furs, feathers, museum specimens, etc., being familiar to all. Ants are 

 famous as scavengers, destroying decaying organic matter in immense 

 quantities, particularly in the tropics. Many Scarabaeidae feed upon 

 excrementitious matter, for example the " tumble-bugs," which are 

 frequently seen in pairs, laboriously rolling along or burying a large ball 

 of dung, which is to serve as food for the larva. 



Insects as Food for Vertebrates. Lizards, frogs and toads are 

 insectivorous, especially toads. The American toad feeds chiefly upon 

 insects, which form 77 per cent, of its food for the season, the remainder 

 consisting of myriopods, spiders, Crustacea, molluscs and worms, accord- 

 ing to the observations of A. H. Kirkland, who states that Lepidoptera 

 form 28 per cent, of the total insect food, Coleoptera 27, Hymenoptera 19 

 and Orthoptera 3 per cent. The toad does not capture dead or motion- 

 less insects but uses its extensile sticky tongue to lick in moving insects 

 or other prey, which it captures with surprising speed and precision. In 

 the cities one often sees many toads under an arc-light engaged in catch- 

 ing insects that fall anywhere near them. Though its diet is varied and 

 somewhat indiscriminate, the toad consumes such a large proportion of 

 noxious insects, such as May beetles and cutworms, that it is unques- 

 tionably of service to man. 



Moles are entirely insectivorous and destroy large numbers of white 

 grubs and caterpillars; field mice and prairie squirrels eat many insects, 

 especially grasshoppers, and the skunk revels in these insects, though it 

 eats beetles frequently, as does also the raccoon, which is to some extent 

 insectivorous. Monkeys are omnivorous but devour many kinds of 

 insects. 



With these hasty references, we may pass at once to the subject of 

 the insect food of fishes and birds. 



