496 BULLETIN 17 9, UNITED STATES NATIONAL MUSEUM 



abdomen whitish. The young female is duller, the upper parts less 

 glossed with steel-blue, and the under parts are more extensively white. 

 This plumage is worn, apparently without much change, for prac- 

 tically a year, or until the next postnuptial molt ; this complete molt 

 takes place after the birds have gone south and produces the well- 

 known adult plumage of each sex.] 



Food. — The whole diet of the purple martin can be fully covered 

 by one word — insects! When that is said, all is said, for that is 

 what the bird subsists upon and nothing else. However, since the 

 same can be said for other birds, some elaboration is necessary in 

 regard to specific kinds of insects. Prof. F. E. L. Beal made an 

 exhaustive study of the martin's food (1918) and found only a few 

 spiders besides true insects. These creatures are so close to insects, 

 however, that, in many minds, they are identical. The Hymenoptera 

 composed the greatest item, amounting to 23 percent, ants and wasps 

 figuring mostly, with a few bees. To accusations that martins de- 

 stroy honeybees, he had a definite answer that in only 5 out of 200 

 stomachs did honeybees appear, and every one of them was a drone. 



Flies amount to 16 percent of the total food and include some of 

 the house-fly family as well as numerous long-legged tipulids. The 

 Hemiptera, or bugs, amounted to 15 percent and included stink bugs, 

 treehoppers, and negro bugs. Beetles composed 12 percent and are 

 represented by May, ground, dung, cotton-boll, and clover weevil 

 beetles. Moths and butterflies were found to some extent. Dragon- 

 flies seem general favorites and were found in 65 stomachs, some of 

 which contained nothing else. 



In connection with this habit of eating dragonflies, Forbush (1929) 

 states that "adult dragonflies are considered to be useful, as they 

 destroy harmful smaller insects, including mosquitoes, but the young 

 of dragonflies are destructive to small fishes, and this habit may neu- 

 tralize the beneficial habits of these insects. As Martins are said 

 to feed heavily at times on mosquitoes, their destruction of dragonflies 

 may be immaterial." 



He says further that "in some instances a great decrease of mos- 

 quitoes is said to have followed the establishment of Martin colonies, 

 but I have had no opportunity to investigate these reports." Cer- 

 tainly, it would be logical to suppose that the area about a thriving 

 martin colony would be freer of mosquitoes than one without these 

 birds. T. S. Roberts (1932), after listing such insect prey as ants, 

 wasps, daddy-long-legs, horse flies and robber flies (which prey on 

 honeybees), bugs, beetles, moths, dragonflies, and spiders, ends with 

 the somewhat remarkable statement that the martin is "rather neutral 

 from an economical standpoint but worthy of protection." He ap- 

 pears to be in an isolated position among most writers, who are 



