BIRDS IN RELATION TO THE ALFALFA WEEVIL. 5 



posed approximately 77 per cent of the food of this sparrow while 

 the remains of a caterpillar and two pupae of a moth added 20 per 

 cent. One bird ate 3 adults and 18 larvae, which comprised 94 

 per cent of the stomach contents, and it also carried 9 larvae in its 

 bill. 



The other July food indicates a tendency toward a more vege- 

 tarian diet. About a fifth of the food was vegetable, while most 

 important among the animal food items other than alfalfa weevils 

 were caterpillars (11.9 per cent), Hemiptera, many of which were 

 leaf hoppers (Jassidae) (9.71), and spiders (2.12). The vegetable 

 element was made up almost exclusively of weed seeds, dandelion 

 and seeds of an unidentified grass occurring most frequently. 



Summary. Brewer's sparrow must be ranked among the most 

 effective enemies of the weevil. During the height of the weevil 

 season it subsists .to the extent of over half its food on this pest. 

 Other insects equally injurious, as plant lice and caterpillars, 

 also fall prey to this bird. In the summer months upward of 90 

 per cent of its food consists of injurious insects and the seeds of 

 weeds. The remaining tenth is composed of insects that are either 

 neutral in their economic relations or indirectly beneficial to man. 

 The amount of grain taken is insignificant. 



DESERT SONG SPARROW. 



(Melospiza melodia fallax.) 



The desert song sparrow is one of the commonest of the native 

 sparrows of Utah during the early spring months, when it may be 

 found in the thickets along streams or irrigating ditches. Con- 

 siderable numbers also pass the winter in favorable spots, which 

 enables them to come in contact with hibernating adult weevils. 



All but 2 of 11 birds collected in April had fed on the insect. 

 Another bird whose stomach was too nearly empty to be of use in 

 this investigation also had eaten weevils. In no case did more than 

 4 individuals appear in one stomach. In bulk they formed 7.35 

 per cent of the food. 



Of other animal food the aquatic larvae of stratiomyid flies com- 

 posed the major portion, nearly 12 per cent. Caterpillars were 

 present in two stomachs (7.27 per cent) and among other items which 

 occurred in smaller quantities were spiders (5.45), dung beetles 

 (Aphodius) (3.9), ground beetles (3.18), click beetles (2.72), and 

 aquatic beetles (2. 03). The vegetable portion was largely the seeds 

 of weeds (31.18 per cent), among which were those of amaranth, 

 pigweed, sunflower, ragweed, brome grass, and a sedge. Two birds 

 had fed extensively on wheat, which brought the average for the 

 month up to 16.45 per cent. 



