. Useful birds and their protection. Containing brief descriptions of the more common and useful species of Massachusetts, with accounts of their food habits, and a chapter on the means of attracting and protecting birds. Birds; Birds. BIRDS, CATERPILLARS, AND PLANT LICE. 121. country from injury by these insects is largely due to the good work of native birds, while the greater destructiveness of this insect in our cities is no doubt in consequence of the scarcity of such birds there. Regarding the immunity of brightly colored caterpillars from destruction by birds, my evidence is mainly of a
. Useful birds and their protection. Containing brief descriptions of the more common and useful species of Massachusetts, with accounts of their food habits, and a chapter on the means of attracting and protecting birds. Birds; Birds. BIRDS, CATERPILLARS, AND PLANT LICE. 121. country from injury by these insects is largely due to the good work of native birds, while the greater destructiveness of this insect in our cities is no doubt in consequence of the scarcity of such birds there. Regarding the immunity of brightly colored caterpillars from destruction by birds, my evidence is mainly of a nega- tive character, and therefore of little value. I have never known birds to eat certain of the most gaudily colored cater- pillars, while others are commonly eaten _,. ,„ ,. J Fig. 40. —Caterpillar of the white-marked tussock by them. It would moth, a destructive shade-tree pest, eaten by many seem that such larvse as are made conspicuous by their coloring must have some means of protection against their enemies. In some instances these bright colors may serve to warn birds that the creature displaying them is distasteful or unfit for food. Usually, however, such caterpillars are not numerous, and must, there- fore, be preyed upon by natural enemies. In that most admirable local economic study of bird life by Dr. Judd, "The Birds of a Maryland Farm," we find the following statements : "The pea plant louse is a new species, unfamiliar to birds, which, however, seldom eat plant lice" (p. 28) ; "The fact that plant lice are not selected by birds has been mentioned in the notes on the pea plant louse" (p. 29). I cannot understand how Dr. Judd could have been led into making such erroneous statements, for the facts are that, while some species of plant lice appear to be ignored by birds, other species often form for them a staple food supply. For example, I have never seen any bird eat the melon plant louse, but several species eat the cabbage
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