548 MAN CONTROLS HIS ENVIRONMENT FOR WEALTH 



of many of our native birds includes insects harmful to vegetation. 

 Investigations undertaken by the United States Department of 



Agriculture (Division of 

 Biological Survey) show 

 that a surprisingly large 

 number of birds, once 

 believed to harm crops, 

 really perform a service 

 to farmers by killing in- 

 jurious insects. Even 

 the much maligned crow 

 eats mice and harmful 

 insects as well as grain 

 and fruit. Swallows in 

 the southern states kill 

 the cotton boll weevil, 

 one of our worst insect 

 pests. Our earliest 

 visitor, the bluebird, in- 

 cludes grasshoppers, ants, 

 spiders, weevils, tent 

 caterpillars, army worms, 

 cutworms, and the cod- 

 ling moth in its diet. 

 The robin, whose pres- 

 ence in the cherry tree 

 we resent during the spring and early part of the summer, 

 includes all of the above and several other pests in its diet. It 

 has a 95 per cent insect diet until June, and after that time about 

 40 per cent of its food is insects. Many birds vary their diet, 

 using the food substances which are most abundant around 

 them. The swifts or swallows eat flies, the cuckoos and blue 

 jays eat hairy caterpillars, which are eaten by few other birds; 

 and much of the winter food of the chickadees consists of eggs 

 of aphids or plant lice. Ants are eaten by many species of 

 birds ; beetle larvae are preferred by crows, blackbirds, and 

 robins. A pair of nesting robins were observed to dig out and eat 



ITICOXI 



.spcfx-r-o'v^ 



The food of some of our most familiar birds, 

 these birds should be protected? 



Which of 



