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 sparrows: a, amaranth; b, crab-grass; c, 

 ragweed; d, pigeon-grass. 



