20 BULLETIN 111, U. S. DEPAETMEXT OF AGBICULTUBE. 



or posts where it is safe from cats and other prowlers. The bird 

 has never been accused, in the writer's knowledge, of depredations 

 upon cultivated crops or of making itself obnoxious in any way. 

 Its food consists largely of fruit obtained from pastures, swamps, 

 and hedgerows, rather than from gardens and orchards. It is a 

 prolific breeder, rearing from four to six young in each brood, and 

 usually bringing off two and frequently three broods a year. Some 

 observers assert that the young of the first brood assist in feeding 

 later broods. 



Food. — For studying the food habits of the eastern bluebird 855 

 stomachs were available. They had been taken in every month of 

 the year and in 28 States, the District of Columbia, and Canada. 

 The food consisted of 68 per cent animal and 32 per cent vegetable 

 matter. 



Animal food. — The animal food is made up. for the most part, 

 of insects, with a few spiders, still fewer myriapods, and a mere 

 trace of other forms. Beetles constitute the second largest item of 

 animal food and for the year average 20.92 per cent of the diet. 

 Of these, 9.61 per cent are useful species, mostly predaceous ground 

 beetles (Carabidae). Few birds exceed this record of destruction 

 of useful beetles. The bluebird eats them every month in such 

 quantities as to indicate that they are an agreeable article of food. 

 The maximum consumption. 19.51 per cent, occurs in May, and the 

 minimum, 2.91, in September. This destruction of useful beetles 

 has been considered by some writers a blot upon the fair name of 

 the bluebird. The present writer, however, holds that a thorough 

 study of the relations of birds and insects will demonstrate that the 

 more omnivorous a bird is in its insect diet the more useful it is; 

 that is, the most useful birds are those that impartially attack all 

 species of insects available and thus tend to maintain a balance in 

 insect life without exterminating one species or allowing another to 

 become overabundant. 



Beetles of the May-beetle family comprise 5.51 per cent of the 

 diet, and while taken to some extent in every month, more than 

 half are eaten in the three months from April to June. They 

 consist mostly of Lachnosterna and small dung beetles (Aphodius) . 

 TTeevils or snout-beetles, eaten but sparingly, amount to only 1.06 

 per cent for the year, and in the month of greatest consumption, 

 February, they reach only 2.95 per cent. Various other beetles, all 

 of a more or less harmful nature, amount to 1.71 per cent. 



Ants in the diet of the bluebird amount to 3.18 per cent, a greater 

 percentage than that of the robin. Other Hymenoptera (wasps and 

 bees) amount to only 1.62 per cent, but it must be borne in mind 

 that the bluebird is not especially active on the wing. Remains of a 

 worker honeybee (Apis mellifera) were found in one stomach. 



