Publisher's Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1912 Excerpt: ...and causing it to wilt and die. Life History.---The aphides pass the winter on clover and vetches, and often increase upon clover so as to do it serious injury, as described on page 211. Where peas area vailable the winged females usually migrate to them about the time peas are 6 or 8 inches high, and give birth to live young, which develop into wingless viviparous females. These females, as do those of subsequent broods throughout the summer, give birth to live young, and reproduction goes on at a rapid rate. According to the observations of Mr. 11. L. Webster, in central Illinois, an aphid becomes grown about eleven days after it is born, lives about twenty-five days and gives birth to about fifty young, though under favorable conditions over one hundred are frequently born. Sixteen generations have been observed from March 23d to October 4th. Winged aphides develop as often as the food-plant becomes overcrowded and it is necessary to migrate to avoid starvation. By midsummer, with the harvesting of the peas, most of the aphides upon them have been destroyed by prcdaceous and parasitic insects and disease, and they are not observed during late summer unless they have been subsisting on clover throughout the season, when they sometimes destroy the crop in August, as has FiG. 234.--The pea-aphis on stems of red clover--natural size. Folsom.) (After been observed in Illinois. In early fall they often become common again on late garden peas, and late in October they migrate to clover. Fewer young are born as the weather gets colder in the fall, and the aphides never become numerous enough to do any injury at that season. Late in October and early November--in the Middle States--as the aphides are migrating to clover, winged males appear, and some of the wingl...
