Economic entomology for the farmer Economic entomology for the economicentomolo00smit_0 Year: 1896 THE INSECT WORLD. 377 out devouring any part of its vegetable envelope, changes to a pupa, and emerges from the gall, leaving it intact, except for the hole through which it emerged. It seems, therefore, as if certain abnormal plant ex- udations secreted in the 433- gall form the actual food of the larva, and it is a curious and interesting fact that the same species in- variably produces in the same place the same kind of gall. In other words, the appearance of the gall is an unfaiHng
Economic entomology for the farmer Economic entomology for the economicentomolo00smit_0 Year: 1896 THE INSECT WORLD. 377 out devouring any part of its vegetable envelope, changes to a pupa, and emerges from the gall, leaving it intact, except for the hole through which it emerged. It seems, therefore, as if certain abnormal plant ex- udations secreted in the 433- gall form the actual food of the larva, and it is a curious and interesting fact that the same species in- variably produces in the same place the same kind of gall. In other words, the appearance of the gall is an unfaiHng index for An oak gaii-fly. the special student to the species that made it. Many interesting problems are connected with the study of these gall-flies ; for instance, in some species both sexes are present early in the season, but in the second or midsummer brood females alone make their appearance. The Fig. 434.
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