210 THE ECONOMIC IMPORTANCE OF ANIMALS 



Agriculture (Division of Biological Survey) show that a surpris- 

 ingly large number of birds once believed to harm crops really 

 perform a service by killing injurious insects. Even the much 

 maligned crow lives to some extent upon insects. Swallows in the 

 Southern states kill the cotton-boll weevil, one of our worst insect 



pests. Our earliest visitor, the 

 bluebird, subsists largely on injuri- 

 ous insects, as do woodpeckers, 

 cuckoos, kingbirds, and many 

 others. The robin, whose pres- 

 ence in the cherry tree we resent, 

 during the rest of the summer 

 does much good by feeding upon 

 noxious insects. Birds use the 

 food substances which are most 

 abundant around them at the 

 time. 1 



Birds eat Weed Seeds. - - Not 

 only do birds aid man in his 

 battles with destructive insects, 

 but seed-eating birds eat the seeds 

 of weeds. Our native sparrows 

 (not the English sparrow), the 



Food of some common birds. Which mourning dove, bobwhite, and 

 of the above birds should be pro- other birds feed largely upon the 



tectedbymanandwhy? 



weeds. This fact alone is sufficient to make birds of vast eco- 

 nomic importance. 



1 The following quotation from I. P. Trimble, A Treatise on the Insect Enemies of 

 Fruit and Shade Trees, bears out this statement: "On the fifth of May, 1864, . . 

 seven different birds . . . had been feeding freely upon small beetles. . . There 

 was a great flight of beetles that day; the atmosphere was teeming with them. 

 A few days after, the air was filled with Ephemera flies, and the same species of birds 

 were then feeding upon them." 



During the outbreak of Rocky Mountain locusts in Nebraska in 1874-1877, 

 Professor Samuel Aughey saw a long-billed marsh wren carry thirty locusts to her 

 young in an hour. At this rate, for seven hours a day, a brood would consume 210 

 locusts per day, and the passerine birds of the eastern half of Nebraska, allowing 

 only twenty broods to the square mile, would destroy daily 162,771,000 of the 



