BIRDS IN RELATION TO THE ALFALFA WEEVIL. 23 



exclusively on these insects, there being only a trace of an alfalfa 

 weevil. In bulk caterpillars formed over a third of the food during 

 May and June. Hymenoptera, in the form of wild bees and ants, 

 composed about a fourth of the contents of five stomachs. Vegetable 

 food entirely of grain, which was probably waste, occurred in three 

 of the stomachs collected in July, and formed about a fifth of the 

 food for the month. 



In spite of the accusation that Bullock's oriole injures peas and 

 small fruit, its good qualities outweigh its harmful traits. It already 

 has a favorable record as an insect destroyer, but we may now add the 

 alfalfa weevil to the list of noxious forms eaten by this bird. 



BREWER'S BLACKBIRD. 



(Euphaffus cyanocephalus.) 



Brewer's, or the white-eyed blackbird (PL III), as it is commonly 

 known in Utah, is the most abundant blackbird of the State. It is 

 very evenly distributed throughout the Salt Lake and the Weber 

 valleys. At a point east of Hoytsville a large tract of irrigated 

 land, much of which is given up to alfalfa, lies rather isolated from 

 the river valley proper and at an altitude of several hundred feet 

 above it. Brewer's blackbirds nested abundantly at the lower level, 

 and as soon as nestlings were hatched the parents began making reg- 

 ular trips to the badly infested fields above, adult birds being ob- 

 served several times traveling considerably over half a mile between 

 the alfalfa and the nest. Another colony made trips of about a 

 third of a mile from their nests in the sagebrush to a portion of a 

 field which was particularly badly infested. Later, parent birds 

 brought their families to the infested fields, where, in flocks of 15 

 to 20, they spent the entire day. 



Nestling and juvenile birds. Under this head are included young 

 birds of any age, from the nestling of a day or two to the fully 

 fledged bird. Of 125 stomachs examined, 78 were for the month of 

 June, 45 for July, and 2 for August. 



In June the weevil formed 20.14 per cent of the stomach contents 

 and was eaten by 60 of the 78 birds. Together these birds had caused 

 the destruction of 231 adults and 904 larvae, an average of 2.96 adults 

 and 11.59 larvse per bird. Though the weevil does not occur in such 

 large quantities in this series as in those collected later, the following 

 records are noteworthy : A fully fledged young bird had eaten from 45 

 to 50 adults and no less than 60 larvse, comprising 87 per cent of the 

 stomach contents. Another had taken from 15 to 20 adults and 60 

 larvse. Sixty-four larvse were found in the stomach of a nestling 

 three or four days old, while four other nestlings had eaten, respec- 

 tively, about 40 adults, 40 larvse, 37 larvae, and 31 larvae and 1 adult. 



