INSECTS IN RELATION TO OTHER ANIMALS 28/ 



served. From a study of one hundred and eight Illinois ^pcri 

 mens, Forbes finds that seventy-eight per cent, of the food for 

 the year consists of insects, eight per cent, of Arachnida, one 

 per cent, of Julidae and only thirteen per cent, of vegetable 

 matter, edible fruits forming merely one per cent, of the entire 

 food. The insects eaten are mostly caterpillars (chiefly cut- 

 worms), Orthoptera (grasshoppers and crickets) and Cole- 

 optera (Carabidae and Scarabseidae). Though some of the 

 insects are more or less beneficial to man, such as Carabidse 

 and Ichneumonidae (respectively predaceous and parasitic), 

 the beneficial elements form only twenty-two per cent, of the 

 food for the year, as against forty-nine per cent, of injurious 

 elements, the remaining twenty-nine per cent, consisting of 

 neutral elements. The food of the nestlings, according to 

 Judd, is essentially like that of the adults, being " beetles, 

 caterpillars, grasshoppers, spiders and a few snails." 



Other Insectivorous Birds. Weed and Dearborn, from 

 whose excellent work the following notes are taken, find that 

 the common chickadee devours immense numbers of canker- 

 worms, and that more than half its food during winter con- 

 sists of insects, largely in the form of eggs, including those of 

 the common tent caterpillar (C. americana) , the fall web- 

 worm (H. citnea) and particularly plant lice, whose eggs, 

 small as they are, form more than one fifth of the entire food ; 

 more than four hundred and fifty of them are sometimes eaten 

 by a single bird in one day, and the total number destroyed 

 annually is inconceivably large. The house wren is almost 

 exclusively insectivorous, feeding upon caterpillars and other 

 larvae, ants, grasshoppers, gnats, beetles, bugs, spiders, and 

 myriopods. The swallows, also, are highly insectivorous; 

 " most of their food is captured on the wing, and consists of 

 small moths, two-winged flies, especially crane-flies, beetles in 

 great variety, flying bugs, and occasionally small dragon-flies. 

 The young are fed with insects." Ninety per cent, of the food 

 of the kingbird " consists of insects, including such noxious 

 species as May-beetles, click-beetles, wheat and fruit weevils. 



