296 BULLETIN 17 9, UNITED STATES NATIONAL MUSEUM 



the adult in color pattern, but darker above and brigliter below. The 

 pileum, wings, and tail are deep "clove brown," and the rest of the 

 upper parts are deep "olive-brown"; the under parts are "primrose 

 yellow," narrowed to a median line on the breast by "olive-brown" 

 streaking on the throat and sides; the median and greater wing 

 coverts are edged with "ochraceous-buff," and the secondaries and 

 tertiaries are tipped with brownish white. 



Dr. Dwight (1900) says: "First winter plumage acquired by a 

 late postjuvenal moult beginning in September which possibly is 

 complete. I have seen no extra-limital specimens but I should expect 

 to find them retaining the brown wing edgings. Pale wing bands 

 are probably acquired at this moult when young birds become prac- 

 tically indistinguishable from adults. First nuptial plumage ac- 

 quired apparently by wear. Birds return from the south in fresh 

 little worn plumage, the young birds with a dull clay -colored lower 

 mandible. Old worn feathers may be found mixed with the new 

 in some specimens, very strongly suggestive of a recent limited 

 prenuptial moult." 



Older birds have a complete postnuptial molt, which may begin 

 in August, but probably oftener in September, or after they have 

 migrated southward. They may also have a partial prenuptial molt, 

 as suggested above. The sexes are alike in all plumages. Fall birds, 

 in fresh plumage, are more brightly colored than spring birds. 



Food. — Professor Beal (1912) examined the contents of 69 stom- 

 achs of the olive-sided flycatcher, collected in 12 States and in 3 

 Provinces of Canada. In his summary he writes : 



The food of this bird is interesting, as it represents the food of a typical 

 flycatcher. With the exception of the vegetable matter in 1 stomach, every- 

 thing it eats could be taken on the wing. Caterpillars, spiders, and millepeds, 

 although found in the stomachs of most flycatchers, are entirely absent. * * * 



The most prominent fact in the food habits of the olive-sided flycatcher is 

 its consumption of honeybees. As it eats no vegetable matter worth mention- 

 ing, its record must rest on its insect food, and honeybees constitute entirely 

 too large a quota for the be.st economic interests. Were the bird as abundant 

 and as domestic as either of the phoebes, there is no doubt that it would be a 

 pest to bee keepers. * * * 



Hymenoptera are the staff of life of the olive-sided flycatcher and form a 

 large percentage of the food of each month. The fewest were taken in May, 

 when they amounted to 74.50 per cent. The average consumption for the season 

 from April to September was 82.56 per cent. They were found in 61 of the 

 63 stomachs, and 26, that is, over 41 per cent of the whole, contained no other 

 food. Of all the birds examined by the Biological Survey, not one subsists so 

 nearly exclusively upon one order of insects. Winged ants were found in 10 

 stomachs and entirely filled 2 of them. A few useful parasitic species were 

 identified, but more interesting than these were 63 honeybees {Apis mellifera), 

 found in 16 stomachs, or 25 per cent of the whole number. Of these, 36 were 

 workers and 27 were males or drones. Thus the bird shows a very decided 



