. Bulletin - Biological Survey. Zoology, Economic. 24 THE RELATION OF SPARROWS TO AGRICULTURE. iiiii'' i PI rows prey on cankerworms and other members of the familj^ Geome- tridse. They also have a decided taste for cutworms, army worms, and their allies, in destroying which the song, field, chipping, grass- hopper, and lark sparrows, and the dickcissel are especially effective. But adult sparrows can not he depended upon to check invasions of certain insect pests, especially hairy caterpillars, because they do not eat them. With orchard trees and others festooned with the webs of the fall web
. Bulletin - Biological Survey. Zoology, Economic. 24 THE RELATION OF SPARROWS TO AGRICULTURE. iiiii'' i PI rows prey on cankerworms and other members of the familj^ Geome- tridse. They also have a decided taste for cutworms, army worms, and their allies, in destroying which the song, field, chipping, grass- hopper, and lark sparrows, and the dickcissel are especially effective. But adult sparrows can not he depended upon to check invasions of certain insect pests, especially hairy caterpillars, because they do not eat them. With orchard trees and others festooned with the webs of the fall web- worm, I have seen the spar- rows, although the}^ were abundant in the vicinit}", re- fuse these insects and select others. At Marshall Hall, Md., on the level bluff across the Potomac from Mount Ver- non, is a fertile farm, on which the field habits of sparrows have been carefully studied (see pp. 29-45). On this farm during August, 1898, the tobacco worms i^ractically ruined the tobacco crop. I collected there at that time 50 s]3arrows, representing the chipping, song, field, grass- hopper, Henslow's, and Eng- lish sparrows, but subsequent stomach examination showed that only one of these birds had eaten a tobacco worm. Weevils, especialh" sucli as injure clover and strawber- ries, they destroy in large numbers, which is surprising, considering that these insects are hard shelled and protect- tively colored. Thej^ eat some species of leaf-beetles (Chryso- melid?e) also, but refuse others. Thus they avoid the potato beetle {Dorypliora 10-Uneata), the two 12-spotted cucumber beetles {Diahro- tica 12-punciata and D. vittata), and the bean flea-beetle {Ceraforna trifurcata),l>ut consume some of the less important pests of the bean. The song, field, and chipping sparrows eat the locust leaf-mining beetle {Odontota dorsalis) and two species of striped flea-beetles (Systena hlanda and S. elongata).. Fto. 13.—Four common weeds the seeds of whicJi are ea:;en hy sparrow
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