420 ANNUAL BEPORT SMITHSONIAN INSTITUTION, 1925 



Whether the pressure thus put on iiruptions of insects is ever effec- 

 tive in siH iirini!: a uorth while degree of control is a topic upon which 

 it is naliiral to be skeptical. Insects are so numerous and propa<;ate 

 so rapidly that it woukl seem they would ahyays evade control bj^ 

 so limited a force as the bird i)opulation. Yet when we consider the 

 results of the feeding habits of birds in other and more easily ob- 

 served directions we begin to see that their consuming capacity is 

 certainly impressive. For instance, consider the devouring of wild 

 fruits b}' birds; it is quite the customary thing for a flock of birds 

 to resort constantly to a certain tree or group of trees for food until 

 the entire crop of fruit is consumed. This process is illustrated 

 nearly every je'dv in the })arks of Washington. When the spring 

 migrating impulse is on, cedar birds usually come to the parks in 

 large numbers, and it is their habit to devote themselves to one kind 

 of berry until it is gone. For instance, should they begin on holly 

 ihey will finish all the holly berries in the Smithsonian Grounds, 

 let us say, then they will next be found in the Capitol Grounds or 

 in some other park w^orking on the hollies there. Then they may 

 turn their attention to cedar berries, if there is a crop, or to barber- 

 ries, or to other fruit available. I have observed in various years that 

 after cleaning up the berries they have even consumed the pods of 

 the Sophora trees, feeding wastefully upon them at first, but later 

 descending to the ground to go over again the remnants of the feast. 

 1 have seen on different occasions flocks of blackbirds, or of purple 

 finches, or robins consume the entire crop of dogwood berries, not 

 only of one or a few trees, but of all the trees in a woodland. Indeed, 

 this manner of feeding is quite characteristic of birds. 



If birds can do such things, if they consume in a brief time all 

 the berries on a tree, is it not equally possible that they can consume 

 likewise all of the insects? The answer is an emphatic and in- 

 disputable "yes." Such clean-up work not only can be, but has 

 been done, and there is here given a summary of the recorded in- 

 stances so far as they have been assembled. 



For convenience the cases are arranged by orders of insects, and 

 it will be understood when the word <;ontrol is used, that our 

 authority has made a statement indicating a high degree of control, 

 and the Avord suppression when the insect concerned has been locally 

 extirpated. The latter cases have already been treated at length 

 in an article entitled " Local Suppression of Insect Pests by Birds," 

 published in the Smithsonian Report for lOSO."* All data used in 

 the following notes on control pertain either to the United States 

 or Canada. 



3 1022. Pp. 411-438, ■{ pis. 



