PLANT LICE
surviving virgins give birth in forlorn hope to a brood that must be destined for the end. But now, it appears, another of those miraculous events that occur so frequently in the lives of insects has happened here, for the members of this new brood are seen at once to be quite different creatures from their parents. When they grow up, it develops that they constitute a sexual generation, composed of females and males! (Plate 2 A, B.)
Feminism is dethroned. The race is saved. The marriage instinct now is dominant, and if marital relations in this new generation are pretty loose, the time is October, and there is much to be accomplished before winter comes.
The sexual females differ from their virgin mothers and grandmothers in being of darker green color and in having a broadly pear-shaped body, widest near the end (Plate 2 A). The males (B) are much smaller than the females, their color is yellowish brown or brownish green, and they have long spiderlike legs on which they actively run about. Neither the males nor the females of the green apple aphis have wings. Soon the females begin to produce, not active young, but eggs (D). The eggs are deposited most anywhere along the apple twigs, in crevices where the bark is rough, and about the bases of the buds. The newly-laid eggs are yellowish or greenish (D), but they soon turn to green, then to dark green, and finally become deep black (E). There are not many of them, for each female lays only from one to a dozen; but it is these eggs that are to remain on the trees through the winter to produce the stem mothers of next spring, who will start another cycle of aphid lire repeating the history of that just closed.
The production of sexual forms in the fall in temperate climates seems to have some immediate connection with the lowered temperature, for in the tropics, it is said, the aphid succession continues indefinitely through parthenogenetic females, and in most tropical species sexual
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