2 a 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, vet 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 (Harpalincz) , 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, 

 1 ^o 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. 



