THE THRUSHES AND THEIR ALLIES. 91 



composed of scavenger-beetles, wire-worms, ground-beetles, 

 grasshoppers, and sumach-berries. Six per cent, of the food 

 was considered to belong to beneficial species and thirty- 

 seven per cent, to those injurious. In April caterpillars 

 formed one-fourth of the food and beetles forty-two per cent. 

 " It is in this month that the bird makes its principal attack 

 upon the predaceous beetles, which are represented by an 

 average of seventeen per cent, eaten by eleven birds." A 

 few Bibio larvae, earthworms, Orthoptera, bugs, and sumach- 

 berries had also been eaten. " The record of May is sub- 

 stantially a duplicate of the April list, except in a few particu- 

 lars. The Bibio larvae are replaced by seven per cent, of 

 adult crane-flies and the ground-beetles drop to four per 

 cent., the balance being almost replaced by the scavenger- 

 beetles and leaf-chafers. . . . With June the robin revolu- 

 tionizes his commissariat. The insect ratios, which have 

 averaged ninety-five per cent, during the preceding months, 

 now drop to forty-two, and remain at or below this point for 

 the rest of the year ; and this lack is compensated by the 

 appearance of fifty-five per cent, of cherries and raspberries. 

 The loss falls chiefly upon the two-winged flies and beetles, 

 the former dropping from eleven per cent, to less than one 

 and the latter from forty-four per cent, to fifteen. The four- 

 teen July birds were evidently revelling in the fruit garden, 

 raspberries, blackberries, and currants forming seventy-nine 

 per cent, of the food." The partial disappearance of fruit 

 supplies in August sent the robins back to insects, although 

 the twenty birds taken during the month had eaten fifty-six 

 per cent, of fruit. "Cherries made forty-four parts of the 

 food of the month, eaten by fourteen of the birds, but two- 

 thirds of these cherries were wild. Tame grapes made three 

 per cent, of the food, berries of the mountain-ash about four 

 per cent., and blackberries from the woods not far from five 

 per cent." Cutworms, crickets, and grasshoppers are impor- 

 tant insect elements for the month. In September fifteen 



