FOOD INJURIOUS IN EFFECT ON AGRICULTURE. 21 



FOOD INJURIOUS IX EFFECT ON AGRICULTURE. 



The injurious part of the food of sparrows, the removal of which 

 tends to cause a harmful effect upon crops, is made up of useful 

 insects and spoils from cultivated crofjs, such as grain and fruit. 

 Beneficial insects seldom amount to more than 2 percent of the food. 

 They consist mostly of enemies of insect pests and a very few flower- 

 fertilizing species, such as certain wasps and some small bees of 

 the genera Andrena and Halictus. The insect enemies are either 

 ground-beetles (Carabidse) or parasitic wasps. The particular ground- 

 beetles selected belong to the less useful predator}' kinds. They are 

 small species, the exact economic position of which is not yet known, 

 and include Amara, Anisodactylus, Agonoderus, Bemhidiiun, and the 

 smaller species of Harpcdus. One species — Agonoderus iDcdlipes — 

 has been found injurious to grain, and in time it and some other slightly 

 carnivorous carabids may become pests like the related Zahrus gibbus 

 of Europe. The i^arasitic Hymenoptera include such wasps as the 

 smaller Iclineumonid?e, the larger Braconid?e, and Scoliida^ of the 

 genera Myzine and Tipliia. But the quantitj^ of useful insects eaten by 

 sparrows is small; omitting those taken b}^ the English and field si3ar- 

 rows, it is insignificant. And though -^ jDercent of the food of the latter 

 consists of useful insects — a larger percentage than is attained by any 

 other member of the sparrow family — yet this record is very favorable 

 compared with those of many birds. The loggerhead shrike and the 

 king-bird, for example, take 12 percent and 20 percent, respectively, 

 of their food in beneficial insects, and there are other birds whose 

 records are still less creditable. 



Cultivated fruit forms no significant i3art of the food of sparrows. 

 The white-crowned sparrow occasionally punctures a few grapes in 

 the East; the English sparrow adds more or less fruit destruction to 

 his many other sins; and it is probable that one or two Avestern spe- 

 cies do some little damage of this kind: but with these exceptions the 

 sparro\y family is harmless to orchard and vinej'ard. 



The English sparrow does so much damage to grain that it is con- 

 sidered a pest, and the native sparrows might naturally be suspected 

 of having similar habits; but though they frequently sample grain in 

 stubble-fields, they have not as yet been found committing serious 

 depredations. In order to compare the grain-eating propensities of 

 the various species, specimens were collected on a farm a few miles 

 south of Washington, D. C, before and after the wheat was cut. Of 

 nineteen native birds, representing song, field, chipping, and grass- 

 hopper sparrows, ouh' two had eaten grain, and these had taken only 

 one kernel each, while, on the other hand, of five English sparrows 

 that were examined eveiy one was gorged Avith wheat. On this par- 

 ticular farm flocks of English sparrows pillage the wheat crop from 

 the time it comes in milk until it is threshed; and attack corn in 



