THE COWBIED. 



25 



especially the last, are the insects that might be supposed to attract 

 the birds to the cattle, but the stomachs do not show that many are 

 eaten, for altogether they amount to less than 3 percent of the food, 

 and the wasps and ants are the most important constituents of this 

 percentage. The wasps are probably picked from flowers while 

 gathering honey and the ants are collected from the ground. The 

 destruction of the latter is a decided benefit and the former can be 

 spared. Hemiptera are represented in the stomach by stink-bugs 

 (Pentatomid^), leaf -hoppers (Jassidse), and one cicada. While some 

 of the pentatomids are useful insects, because of their habit of prey- 

 ing upon others of a noxious character, many of them are serious 



Fig. 3.— Diagram showing proportions of animal and vegetable food of cowbird in each month of the 

 year. (The figures in the left margins indicate percentages. ) 



pests; so on the whole it is probable that birds do little harm by eating 

 them. The so-called leaf -hoppers live to a great extent upon grass 

 and might very properly be called grasshoppers were it not that that 

 name has been appropriated for other insects. Those eaten are so 

 little that it would require a number of them to fill the stomach of 

 even a small bird. All are harmful, and some, as for example those 

 that feed on the grapevine and rose, are very injurious. Cowbirds 

 eat a great manj^ of these leaf -hoppers, which in some stomachs amount 

 to 60 percent of the whole contents. The greater number are eaten 

 in June and July, but the aggregate for the year is small, about 1^ 

 percent. 



