BIEDS IN RELATION TO THE ALFALFA WEEVIL. 41 



No rough-wings were collected in August, but in all probability 

 these birds continue to prey on the insect during late summer when- 

 ever a flight takes place. 



The rough-wing probably is as effective an enemy of the weevil as 

 the cliff swallow, but, like the latter, its work is limited to warm, fair 

 days of spring and late summer. In addition to the good work of 

 this bird upon this insect its economic status, based on other activities, 

 is in its favor. 



YELLOW WARBLER. 



(Dendroica wstiva (estiva.) 



The yellow warbler is the most common of breeding warblers 

 throughout the Salt Lake Valley. Whenever its favorite nesting 

 site of willows along the banks of streams and irrigating ditches 

 occurs about the borders of alfalfa fields, this bird is brought in con- 

 tact with the weevil. 



Five birds were collected in June and two in July. Only those 

 taken in the latter month were feeding on the weevil. One had eaten 

 11 larvae and 1 adult, the other 6 larvse. Besides, the latter had in 

 its bill 3 weevil iarvse, a bug, and 9 flies. In bulk the weevil com- 

 posed nearly a fourth of the food of the two. 



The other yellow warblers had fed extensively on caterpillars, 

 which were found in each of the stomachs and formed nearly 

 70 per cent of the food. One half-grown nestling had been fed 

 exclusively on these insects. Small Hymenoptera, some of which 

 were parasitic, were next in abundance, forming nearly a fifth of the 

 contents. 



Although abundant about the borders of alfalfa fields, yellow war- 

 blers were seldom observed dropping down to them in search of 

 food. The upper branches of willows are their favorite resorts and 

 apparently their food is largely secured from such places. 



MACGILLIVRAY'S WARBLER. 



(Oporomis tolmiei.) 



Listing Macgillivray's warbler as an enemy of the weevil is based 

 on the examination of only one stomach. Two breeding adult weevils 

 eaten in May formed about 2 per cent of the contents. There were 

 also present the remains of a click beetle, a dung beetle, a flea beetle 

 (Systena sp.), and a large amount of unidentified insect fragments. 



LONG-TAILED CHAT. 



(Icteria virens lonfficauda.) 



Our knowledge of the long-tailed chat as a weevil destroyer is 

 based on the examination of three stomachs. In two the insect was 

 present, one containing a mere trace of an adult, and in the other 2 

 adults composed about 3 per cent of the food. 



