INSECTS 



241 



birds will congregate in larger numbers to feast upon the 

 seeds. 



Food Habits of Birds. Through the Biological Survey 

 of the United States Department of Agriculture, the food 

 habits of very many species of birds have been studied and 

 published, so that farmers, and everyone else for that mat- 

 ter, may know exactly to what extent we are indebted to the 



FIG. 140. Digger-wasp carrying a cicada to its homo. 



FIG. 141. Sphinx caterpillar covered with cocoons of parasites. (From Smith' 



"Insect Friends and Enemies.") 



birds for their help in keeping down the numbers of destruc- 

 tive insects and the weed pests that would soon literally take 

 the country, were it not for the activities of the birds. 



Through the studies made in the Biological Survey, 

 which have covered a long period of years, it has been deter- 

 mined that very few species of birds can actually be called 

 harmful to the interests of man. 



Harmful Birds. Three hawks Cooper's hawk, the 

 sharpshinned hawk, and the goshawk are the three that 

 commit the most depredations against chicken yards, and 



