FOOD BENEFICIAL IX EFFECT <>X AGRICULTURE. 23 
FOOD BENEFICIAL IN EFFECT OX 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 Locustidae), caterpillars, principally Xoetuida? (that is. cut- 
worms, army worms, and their allies) and some Geometrida?, such as 
cankerworms and their allies, and beetles of various families — Chry- 
somelidae or leaf-beetles, Elaterida? or click-beetles, and Rhyncho- 
phora or weevils. Conspicuous among the genera of beetles met with 
in stomachs of birds are System:!. IGpitrix, Odovdota, Limonius, Dras- 
/< rius, SitoneSj and Phytonomus. Bugs are eaten to an unimportant 
extent, and constitute about 1 percent of the food. The plant-feeding 
forms include such Heteroptera as some of the smaller soldier bugs 
(Pentatomidae), leaf-bugs (Capsiuse). a few such Homoptera as leaf- 
hoppers (Jassidse), and in very rare instances plant-lice (Aphidida?). 
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 trrasshoppei'S are much Fig. 12 — Rocky Mountain locust I after 
more' injurious than others. The most ^jT^ hy Divisi ° n ° f Em °" 
destructive species is the Rocky Moun- 
tain locust (Mdanopba§ 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, 1 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 16f percent 
of the food of the chipping sparrow, 23£ percent of that of the field 
sparrow, and -43 percent of that of the dickcissel. 2 Nearly all spar- 
First Ann. Report U. S. Entomological Commission. App. II. pp. 29-32, 1878. 
1 Bull. 111. State Laboratory Nat. Hist., Vol. I, No. 6, p. 12, 1883. 
