INSECTS IN RELATION TO OTHER ANIMALS 289 



quail and prairie hen, enormous numbers. Even shore birds, 

 such as geese, ducks, gulls and pelicans came to share in the 

 feast. Aughey estimated that the locusts eaten in one day by 

 the passerine birds of the eastern half of Nebraska were 

 sufficient to destroy in a single day 174.397 tons of crops, 

 valued at $1,743.97. 



Weed and Dearborn state that, of Hemiptera, Jassidae are very 

 often found in the stomachs of birds, and that aphids and their 

 eggs form a large part of the food of many of the smaller birds, 

 such as the warblers, nuthatches, kinglets and chickadees. 

 " A large proportion of the caterpillars of the Lepidoptera are 

 eagerly devoured by birds, forming an important element of 

 the food of many species." The hairy caterpillars are eaten 

 by cuckoos and blue- jays and the large saturniid caterpillars, 

 such as cecropia and polyphemus, by some of the hawks. Al- 

 most all kinds of Coleoptera are food for birds, but especially 

 the grubs of Scarabaeidae, which are eagerly devoured by 

 robins, blackbirds, crows and other birds. Of the Diptera, 

 Cecidomyiidae and other gnats are eaten by swallows, swifts 

 and night hawks ; while Tlpulidae are often found in the stom- 

 achs of birds. Among Hymenoptera, ants are eaten exten- 

 sively by woodpeckers, catbirds and many other species, as are 

 als^o Ichneumonidae and other parasitic forms these last by 

 the flycatchers in particular. 



The Regulative Action of Birds upon Insect Oscilla- 

 tions. The worst injuries by insects are done by species that 

 fluctuate excessively in number as the result of variations in 

 those manifold forces that act as checks upon the multiplica- 

 tion of the species. 



In order to determine whether birds do anything to reduce 

 existing oscillations of injurious insects, Professor Forbes 

 made some admirable studies upon the food of birds which 

 were shot in an Illinois apple orchard which was being ravaged 

 by canker-worms. In this orchard, birds were present in 

 extraordinary number and variety, there being at least thirty- 

 five species, most of which were studied by Forbes, from 



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