Page:Insects - Their Ways and Means of Living.djvu/199

 LICE

early part of the season the individuals of this species are round particularly on the under surfaces of the apple leaves. They cause the infested leaves to curl and to become distorted in a haracteristic manner (Fig. 96). The stem mothers (Fig. 97 .A., B) begin giving birth to young (C) about twenty-four hours after reaching ma- turity, and any one of the mothers, during the course of her lire of from ten to thirty days, may produce an aver- age family of fifty or more daughters, for all her offspring are females, too. When these daughters grow up, however, none of them is exactly like their mother. They all have one more segment in each antenna; most of them are wing- less (D), but many of them have wings--some, mere padlike stumps, but others well developed or- gans capable of flight (Fig. 97 E). Both the wingless and the winged individuals of this second generation are also parthenogenetic, and they give birth to a third generation like them- selves, including wing- less, half-winged, and fully-winged forms, but with a greater propor- Fie. 9 6. Leaves of apple infested and tion of the last. From distorted by the green apple aphis on under surfaces now on there follows a large number of such generations continuing through the season. The winged forms fly from one tree to another, or to a distant orchard, and round new colonies. In

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INSECTS