FOOD BEKEFIOIAL m EFFECT ON AGRICULTURE. 23 



FOOD BENEFICIAL IN EFFECT ON AGRICULTURE. 



The beneficial part of the food of sparrows is made up of insect 

 pests and the seeds of weeds. Insect pests amount to from 10 to 20 per- 

 cent of the year's food, and are for the most part grasshoppers (Acri- 

 didse and Locustid^e), caterpillars, principally Noctuidse (that is, cut- 

 worms, army worms, and their allies) and some Geometridae, such as 

 cankerworms and their allies, and beetles of various families — Chry- 

 somelidse or leaf-beetles, Elateridae or click-beetles, and Rhyncho- 

 phora or weevils. Conspicuous among the genera of beetles met with 

 in stomachs of birds are Systena, Epitrix, Odontota, Limonius, Dras- 

 terius, Sitones, and Phytonomus. Bugs are eaten to an unimportant 

 extent, and constitute about 1 percent of the food. The plant-feeding 

 forms include such Heterpptera as some of the smaller soldier bugs 

 (Pentatomidse), leaf-bugs (Capsidse), a few such Homoptera as leaf- 

 hoppers (Jassidse), and in very rare instances plant-lice (Aphidid?e). 

 Insects seldom form more than a third of the food of adult sparrows 

 for the year, but their nestlings are practically entirely insectivorous; 

 on which account these birds, in raising from two to three broods a 

 season among agricultural crops, do 

 their greatest good as destroyers of 

 insect pests by cramming countless num- 

 bers of caterpillars and grasshoppers 

 down the throats of their ravenous 



young. Some grasshoppers are much Fiq.12.— Rocky Mountain locust (after 



more injurious than others. The most ^^togyT"^ '''' ""'^'''^^ ""' "'''''" 

 destructive species is the Rocky Moun- 

 tain locust {Melanoplus spretus — see fig. 12), which at intervals invades 

 the plains of the central United States in such numbers as to actually 

 hide the sun. These insects travel onward, sweeping away every 

 vestige of green vegetation in their path, and bringing destruction 

 and desolation to thousands of farms. As shown by the investiga- 

 tions of Prof. Samuel Aughey in Nebraska,^ the native sparrows 

 perform a useful part in aiding to check these invasions. 



In studying the efficiency of birds in checking an uprising of the 

 cankerworm (Anisopteryx vernata) in Illinois, Prof. S. A. Forbes 

 collected birds in a bearing apple orchard which had been so injured 

 by the worms for several years that it looked as though it had been 

 swept by fire. Among these birds were the grasshopper sparrow, the 

 chipping sparrow, the field sparrow, and the dickcissel. The exami- 

 nation of their stomachs showed that although cankerworms were 

 not eaten by the grasshopper sparrow, they amounted to 16| percent 

 of the food of the chipping sparrow, 23| percent of that of the field 

 sparrow, and 43 percent of that of the dickcissel.^ Nearly all spar- 



^ First Ann. Report U. S. Entomological Commission, App. II, pp. 29-32, 1878. 

 '^Bull. 111. State Laboratory Nat. Hist., Vol. I, No. 6, p. 12, 1888. 



