2 4 
Allen on Insectivorous Birds. 
may even injure us, ... . especially by killing so many carniv- 
orous or parasitic insects, which render us the greatest service.” 
Reasons are also assigned why so many of the really noxious ones 
escape capture, either through their minuteness, their habits, or 
through special means of concealment or protection. 
As Professor Forbes observes, the question of the food of birds 
is almost entirely a question for entomologists and botanists, 
although it has hitherto been left almost wholly to ornithologists, 
who have not usually the special knowledge requisite for its in- 
vestigation even had they the desire to pursue this branch of 
inquiry. For this reason he hopes the attention of our economic 
entomologists will be turned in this direction, and has accordingly 
laid M. Perris’s paper before them. 
Professor Forbes has undertaken the investigation of the food 
of the Thrushes and of the Bluebird. His examination has thus 
far been preliminary or on too limited a scale to give conclusive 
results, yet yielding deductions that go far to show how greatly 
such studies are likely to revolutionize current opinion respecting 
the utility of birds as destroyers of noxious insects. His report 
on the food of the Thrush family ( Turdidce ) * is based on 
the examination of the stomachs of fifty-one Robins, thirty-seven 
Catbirds, twenty-eight Brown Thrushes, eleven Wood Thrushes, 
eighteen Hermit Thrushes, eight “ Alice’s Thrushes,” six “ Swain- 
son’s Thrushes,” and one Wilson’s Thrush, shot in Illinois in 
various months from March to September. While the number 
of specimens is small, Professor Forbes claims that no equal 
number “ has been previously studied with equal care” and gives 
his results “as hypotheses, more or less probable, but requiring 
verification by further study.” A rigid examination of the food 
elements in these examples “ determines the hitherto unexpected 
fact that the family is inordinately destructive to predaceous bee- 
tles {Harjoalincz) , seven per cent, of the food of the 150 specimens 
consisting of these highly beneficial insects. When we remember 
that one predaceous insect must destroy many times its own bulk 
of other insects during its life, we see the importance of this fact 
in respect to the economical value of these birds. . . . Of the 
150 Thrushes examined, forty-six per cent, had taken Carabidce 
* The Food of Birds. Trans. Illinois State Hort. Soc., Vol. XIII, 1879 (1880), pp. 
120-172. — The Food-habits of Thrushes. Amer. Entomologist, new ser., Vol. I, pp. 
12, 13, Jan., 1880. 
