BIRDS, CATERPILLARS, AND PLANT LICE. 123 



opportunity to judge for himself as to the value of these 

 birds. If this volume does no more than to correct the 

 prevalent erroneous impression regarding the relations be- 

 tween birds and hairy caterpillars, and call attention to 

 the necessity of protecting the birds that eat such larva}, it 

 will have accomplished something worth while. The ques- 

 tion whether or not birds will eat the caterpillars of Bom- 

 bycid moths is of vast importance to the Commonwealth, 

 the adjoining States, and the nation ; for, unless we can 

 get help from the natural enemies of the gipsy moth and 

 the brown-tail moth, the fight against these insects is likely 

 to cost the State many millions of dollars in the end, while 

 other States that surely will be invaded must suffer also. 

 If it can be shown that birds are capable of doing effective 

 work against these insects, it ought not to be difficult to 

 create such a public sentiment in favor of bird protection as 

 will result in a considerable increase in the numbers of the 

 useful species which obtain a part of their sustenance from 

 this abundant food supply. 



In May, 1898, injurious insects were unusually prominent 

 in the Middlesex Fells. The birches swarmed with aphids ; 

 cankerworms appeared on the apple and elm trees ; the 

 growing webs of tent caterpillars were seen on most of the 

 wild apple and wild cherry trees ; forest caterpillars were 

 gathering on oaks and maples ; sawflies, mosquitoes, ants, 

 leaf-rollers, and many other injurious species were abun- 

 dant. The brown-tail moth was just getting a good foothold 

 in the woods, while the ever-present gipsy moth larvae were 

 beginning to swarm up the trees from the furry egg clus- 

 ters hidden among the loose stones and seamed ledges of 

 the rocky hills. As usual at such times, birds were present 

 in large numbers. Warblers were flitting among the birch 

 trees, regaling themselves on countless thousands of plant 



O O m _ 



lice, plucking young tent caterpillars from the opening buds 

 of wild apple trees or from the fast-forming webs. They 

 alighted on the tree trunks and climbed around them, as they 

 eagerly sought tiny hairy larvae of the gipsy moth, or flut- 

 tered in the sunlight as they chased winged gnats in air. 

 It seemed that there could be no better opportunity to ob- 



