BIRDS IN RELATION TO THE ALFALFA WEEVIL. 29 



tents. Among the weed seeds were those of filaree (Erodium cicu- 

 tarium), sunflower (Helianthus sp.), pigweed {Amaranthus retro- 

 flexus and A. blitoides), cockle (Vaccaria vaccaria), smartweed 

 (Polygonum spp.), panic grass (Panicum sp.), and brome grass 

 (Bromus sp.). 



Four vesper sparrows were collected in May, three of which had 

 eaten the weevil, the fourth having been secured in a wooded ravine 

 some distance from the nearest field. The weevil formed nearly 40 

 per cent of the stomach contents of the four, with an average of 

 about three adults and six larvae per bird. In the remaining food, 

 caterpillars (8.25 per cent), grain (11 per cent), and weed seeds (42 

 per cent) predominate. 



Examination of a series of 19 stomachs in June shows that these 

 fringilline birds are decidedly insectivorous during the breeding 

 season. Every one had fed on the weevil, and in 4 it amounted 

 to over 95 per cent of the food, while the average for the month was 

 nearly 60 per cent. As many birds were collected at a time when 

 the larvae were most abundant, this form of the insect appeared in 

 large numbers in some stomachs. An average of 3.8 adults and over 

 24 larvse per bird was recorded. One bird had eaten 2 adults and 60 

 larvae, another 6 adults and 55 larvae, and a third 1 adult and 50 

 larvae. The weevil contents of several others are as follows: 5 or 

 6 adults and about 45 larvae ; 2 adults and 45 larvae ; 1 adult and 40 

 larvae ; 7 adults and 28 larvae ; and 10 adults and 21 larvae. 



Of the other animal food items Hemiptera, composed chiefly of the 

 small cicada, Platypedia putnami, so abundant in the oak chaparral 

 of the foothills at this time of the year, formed the next largest 

 portion (7.79 per cent). Clover root curculios (Sitones), "bill 

 bugs " (Sphenophorus) , caterpillars, parasitic Hymenoptera, and 

 grasshoppers follow in the order named. The vegetable portion 

 (10.63 per cent) is divided between grain and the weed seeds pre- 

 viously mentioned. 



For the month of July a larger series of stomachs (44) affords 

 added evidence of the remarkable work of these sparrows as de- 

 stroyers of the weevil. Only one had failed to feed on the insect. 

 There was an increase in the average number of adults taken (5.36) 

 and a decrease in the number of larvae (18.43) as compared with the 

 preceding month, because of the presence of more adults of the year's 

 brood during July. Animal food comprised 73.02 per cent of the 

 contents, 52.09 per cent being weevils. One bird had eaten 65 larvae 

 and 2 adults and was carrying 17 larvae of the weevil in her bill for 

 her young. Another had taken 46 larvae and 22 adults. The stomach 

 of a full-fledged sparrow collected in July, and .still being fed by its 

 parents, contained 45 larvae and 8 adults. Eighteen other birds had 



