MISCELLANEOUS ENEMIES. 



135 



Birds. 



Birds devour immense numbers of the spring grain-aphis. Miss 

 Margaret Morse, of Clark University, has been kind enough to conduct 

 some experiments for us in feeding Toxoptera to quail. She has 

 learned that they are very fond of the aphidids and estimates that 

 about 5,000 individual Toxoptera were eaten by a single quail in one 

 day, preference being shown for those that were unparasitized. 



Mr. W. L. McAtee, of the Biological Survey of the United States 

 Department of Agriculture, made some special studies of the aphis- 

 eating habits of some of our birds in March- April, 1909, at Winston- 

 Salem, N. C, at the time Toxoptera was so destructive in that 

 vicinity. He states that in a wheat field of about 

 100 acres there were over 3,000 birds present 

 daily; sometimes the number ran as high as 8,000 

 to 9,000. So large a number of birds would be 

 found in the fields only during migration, and 

 even at that time the presence of so many indi- 

 cates that they were attracted to the fields by 

 the abundant food. In so far as could be ascer- 

 tained, about nine-tenths of the birds were feed- 

 ing upon aphidids (including Toxoptera graminum, 

 Macrosiphum granaria, and Aphis avense), some 

 taking as many as 180 at a single meal. These 

 aphidids are very small, soft-bodied insects and 

 many meals would be required by a bird in a 

 single day to satisfy its hunger. The average 

 number per meal was at least 50, and we may 

 assume that 6 times this number were taken per 

 day. On this basis the number of aphidids de- 

 stroyed by birds on the farm daily during the 

 migration season is 90,000. Below is a partial 

 list of the species Mr. McAtee found devouring Toxoptera at 

 Winston-Salem. A complete list can not be given at this time, 

 since his studies are not yet finished; many species will undoubtedly 

 be added. 



Goldfinch (Astragalinus tristis). 



Vesper sparrow (Pooecetes gramineus). 



Savanna sparrow (Passerculus sandwichensis savanna). 



Chipping sparrow (Spizella socialis). 



Song sparrow (Melospiza melodia). 



All of these birds occur over the entire South. 



MISCELLANEOUS ENEMIES OF TOXOPTERA. 



Under the head of miscellaneous enemies may be considered ene- 

 mies that are of very slight economic importance; those, in other 

 words, that have been observed occasionally attacking Toxoptera. 



Fig. 4S.—Aphidoletes sp., 

 cecidomyiid larva 

 which attacks the 

 spring grain-aphis, a, 

 Larva; 6, anterior ex- 

 t r e m i t y protruded , 

 showing breastbone; c, 

 ventral view of poste- 

 rior segment, a, Much 

 enlarged; b, c, greatly 

 enlarged. (Original.) 



