316 U. S. NATIONAL MUSEUM BULLETIN 211 



females, but texture of plumage very different and feathers without 

 gloss". The immature male in first winter plumage is "similar to the 

 adult male, but feathers of head, neck, back, scapulars, chest, and 

 sides narrowly tipped with grayish brown (paler and more buffy on 

 underparts)." 



Food. — The Brewer's blackbird feeds both on animal matter, 

 principally insects, and vegetable matter, principally seeds. 



Analysis of the stomach contents of six mature birds collected in 

 an alfalfa and wheat area on the outskirts of Meadow, Millard County, 

 Utah, on June 10, 1943, by Knowlton and Telford (1946) are reported 

 as follows: 



One stomach held 2 adult and 63 nymphal treehoppers, Campylenchia latipes 

 (Say), besides other insects. Another stomach contained 8 adult and 22 larval 

 alfalfa weevils, a clover leaf weevil, a histerid beetle and an elaterid beetle, etc. 

 Total recognizable contents consisted of: 17 nymphal grasshoppers; the 18 Hemip- 

 tera included 1 pentatomid, 3 lygaeids and 1 mirid; of the 84 Homoptera, 65 were 

 membracids, 15 were aphids including 8 pea aphids, and 2 leafhoppers; 57 Coleop- 

 tera, among them 19 adult and 16 larval alfalfa weevils, 2 clickbeetles, 3 white 

 grubs, a buprestid and histerid; 1 adult Trichopteron ; 40 larval Lepidoptera; 

 2 larval Diptera; 10 of the 15 Hymenoptera present were ants. Three spiders 

 also were present. 



This interesting blackbird is sufficiently abundant in many parts of Utah to 

 be of importance in the control of cutworms, grasshoppers and certain other 

 insect pests. 



The termite Zootermopsis angusticollis has been observed by Cowan 

 (1942) as a food of the Brewer's blackbird in British Columbia. La 

 Rivers (1941) while working on a program for the control of the 

 Mormon cricket (Anabrus simplex) in northern Nevada during the 

 summer of 1939, made the following observations: 



This bird [the Brewer's blackbird], in company with the Sage Thrasher [Oreo- 

 scoptes montanus] and Western Meadowlark [Sturnella neglecta], is one of the 

 destructive "Big Three" of the northern Nevada cricket fields. It has been 

 known to destroy entire bands of adult crickets, but has never been reported 

 as working on the egg-beds. It can safely be said that each of these three species 

 of birds is responsible for more destruction of the Mormon cricket than all the 

 other species together. * * * However, while the blackbirds feed extensively on 

 the crickets in lean areas, they may almost ignore them adjacent to fields where 

 they can obtain abundant seed. In one region south of Whiterock I observed 

 a band of approximately 200 blackbirds working on a hillside which bore a 

 cricket population of five per square foot. After an hour's observation I inves- 

 tigated their work and found, at the spot, only one attacked cricket to the square 

 yard. Females [the birds ate only female crickets] constituted fifty percent of 

 the cricket population, and, on this basis, the kill ratio amounted to 1 out of 

 22.5, a very low figure. 



Knowlton and Harmston (1943), working on grasshoppers and 

 crickets eaten by birds in Utah, examined the stomach contents of 

 105 Euphagus cyanocephalus. They report "40 contained Orthoptera, 



