308 



BRANCH CHORDATA 



to the South and are of great specific value there by reason of their 

 raids upon the cotton-boll weevil, so they should be encouraged 



and protected from the English 

 sparrow. Orioles do royal service 

 in catching weevils on the bolls. 

 Blackbirds, wrens, and fly-catchers 

 do good work. 



Sparrows prey upon the green 

 wheat aphid of North Carolina. 



During an outbreak of canker- 

 worm in a central Illinois apple 

 orchard the investigations of Prof. 

 S. A. Forbes showed that the food 

 of robins, catbirds, brown thrashers, 

 and bluebirds consisted of 96 per 

 cent, insects, of which 16 per cent, 

 was cankerworms, while the food of 

 the house wrens he examined was 

 50 per cent, cankerworms; 25 per 

 cent, of the food of the hairy and 

 downy woodpeckers consists of bor- 

 ing larvae. 



It is true that birds eat a certain 

 percentage of fruit and seeds, but 

 the entire amount of vegetable 

 matter is usually much less than 

 the animal matter consumed. A 

 large proportion of the seeds eaten 

 are weed seeds (Fig. 253), such as 

 dandelion, dock, knot-weed, purs- 

 lane, pigeon-grass, and rag-weed. 1 

 The grain which birds eat is, much 

 of it, picked up from the waste 

 matter about the farm-yard. 



Doctor Judd 2 says the great horned owl, the sharp-shinned 

 and Cooper hawk, and the English sparrow are injurious birds 



1 Jackson and Daugherty, " Agriculture through the Laboratory and 

 School Garden." 



2 Linville and Kelly. 



Fig. 253. Weed seeds 

 commonly eaten by birds: 

 a, Birdweed; b, lambs' quar- 

 ter; c, purslane; d, amaranth; 

 e, spotted spurge; /, ragweed; 

 g, pigeon grass; h, dandelion. 

 (Biological Survey, U. S. 

 Dept. Agricul.) 



