28 



Fig. 1. — Chickadee hunting 

 insects. 



a greenhouse were infested by some two thousand plant lice, which 

 were all consumed in a few hours by a single titmouse, liudolphus 

 Bingham of Camden, N J., states that he kept a winter garden almost 

 entirely free from plant lice, wasps and flies by confining an indigo bird 



there. He also kept a few native sparrows 

 in a large greenhouse, and as a result the 

 place suffered very little from insect attacks. 

 After the birds had been introduced he found 

 it unnecessary to fumigate. These experi- 

 ments determine only that birds will eat 

 aphids when confined with them, but any 

 one who will watch the warblers and other 

 small birds in May among the birch or other 

 woods infested by aphids will be convinced 

 that they take vast numbers from choice. 

 My assistant, Mr. F. H. Mosher, watched 

 a pair of Maryland yellow-throats eating 

 plant lice from the birches in the Middlesex 

 Fells reservation in Maiden, May 28, 1898. 

 One of them ate 89 of these tiny insects in 

 one minute and they continued eating at that 

 rate for forty minutes. Mr. Mosher states 

 that they must have eaten considerably over 

 7,000 in that time. This seems hardly credible, but Mr. Mosher is a 

 very careful, painstaking and trustworthy witness. He adds that the 

 birds made several other visits to the tree during the forenoon and con- 

 tinued feeding as at first. 



The larva? of the Lepidoptera, commonly called caterpillars, are 

 among the worst enemies of trees, and where they are numerous they 

 form at least two-thirds of the food of the warblers. Probably all 

 woodland birds, from hawks, crows and owls down to the tiny titmice, 

 wrens and kinglets, feed on smooth-skinned caterpillars, while at least 

 fifty species are now known to feed on the spiny and hairy caterpillars. 

 It is largely due to a lack of native birds that the shade trees in our 

 cities are so overrun with caterpillars. While the imported sparrow 

 keeps down the spanworms it does not check many other pests. When 

 the imported leopard moth appeared in New York and Brooklyn, caus- 

 ing great havoc among the trees in the parks, it was feared that as the 

 insect spread it would become a serious enemy to the trees of the entire 

 country. But I am informed by Dr. J. B. Smith, State entomologist of 

 New Jersey, that this moth is doing little damage in the country dis- 

 tricts, where the native birds seem to keep it in check. At first it looked 

 as if the large larva? would escape the birds because of their habits. 

 They are borers, beginning life within the small twigs, and when these 

 quarters get too narrow for them they eat holes out and crawl down 

 outside to larger twigs. It is then they are taken by many native birds, 

 though the imported sparrows do not appear to check them. Dr. Smith 

 says that the woodpeckers eat the female moths and probably drag the 

 young larva? out of the smaller twigs. The American silkworm, the 

 larva? of Telea polyphemus, is one of the largest and most voracious of 

 our caterpillars, and should it increase as rapidly as the gypsy moth it 

 would become a fearful pest, but it is noticeable that this and other 

 allied species of great size never reach a destructive height. The prin- 

 cipal reason for their scarcity is that they are eagerly eaten by birds. 

 Hawks, owls, goatsuckers, woodpeckers, jays, robins, tanagers, black- 

 birds and other species capture these lai-ge caterpillars. When Mr. 

 Leopold Trouvelot was engaged in raising Amex-ican silkworms at Med- 

 ford the robins came from all quarters to destroy them, and gave him 

 more trouble than all other birds combined. 

 Mr. Trouvelot says that one of these caterpillars will consume in fifty- 



