. A text-book of agricultural zoology. Zoology, Economic. PLANT-LICE. 237 leaves of the infested plants and blocks up their stomata. All Aphides have a mealy or waxy substance on the skin which repels water. Winged and wingless females occur, the males being also often winged. Parthenogenetic reproduction takes place; both oviparous and viviparous females are found in aU species. The wingless forms are generally asexual, and so are the summer winged females. Ova are usually laid only in the autumn by the oviparous female after fertilisation by. Fig. 121.—Cherry Aphis (Myeus cerasi). a. Winged
. A text-book of agricultural zoology. Zoology, Economic. PLANT-LICE. 237 leaves of the infested plants and blocks up their stomata. All Aphides have a mealy or waxy substance on the skin which repels water. Winged and wingless females occur, the males being also often winged. Parthenogenetic reproduction takes place; both oviparous and viviparous females are found in aU species. The wingless forms are generally asexual, and so are the summer winged females. Ova are usually laid only in the autumn by the oviparous female after fertilisation by. Fig. 121.—Cherry Aphis (Myeus cerasi). a. Winged 9 ; b, apterous ?. the male. The tarsi are two-jointed, and the wings contain very few veins, by which the Dolphins, as they are called in Kent, are partly classified. The reproductive powers of these insects are enormous as well as peculiar. The wingless female, starting in the spring, produces with great rapidity living young without the agency of a male; these asexuaUy produced young or lice soon grow sufficiently to start reproducing again, and so on for eight or nine generations. As a rule, a plant becomes smothered by these wingless forms; and in the summer. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Theobald, Frederick Vincent, 1868-1930. Edinburgh and London, W. Blackwood and sons
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1899
