PLANT LICE
Since special cases are always more convincing than general statements, let us follow the seasonal history of some particular aphids, taking as examples the species that commonly infest the apple.
Let the time be a day in the early part of March. Probably a raw, gusty wind is blowing from the northwest, and only the silver maples with their dark purplish clusters of frowzy flowers already open give any suggestion of the approach of spring. Find an old apple tree somewhere that has not been sprayed, the kind of tree an entomologist always likes to have around, since it is sure to be full of insects. Look closely at the ends
Fig. 91. Aphis eggs on apple twigs in March; an enlarged egg below
of some of the twigs and you will probably find a number of little shiny black things stuck close to the bark, especially about the bases of the buds, or tucked under the projecting edges of scars and tiny crevices (Fig. 91). Each little speck is oval and about one thirty-sixth of an inch in length.
To the touch the objects are firm, but elastic, and if you puncture one a pulpy liquid issues from it; or so it appears, at least, to the naked eye—a microscope would show that in this liquid there is organization. In short, the tiny capsule contains a young aphid, because it is an aphid egg. The egg was deposited on the twig last fall by a female aphis, and its living contents have remained alive since then, though fully exposed to the inclemencies of winter.
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