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Show ' The Woolly Aphis. The woolly aphis is, I think, the - ' worst of this horrid tribe of plant destroyers (plant lice). It is . a yellowish green or olivaeious color, and bears long wool on ita abdo-i abdo-i , men, which gives it its common specific name. This louse works only on deciduous tree3, and chiefly chief-ly on apple and pear. It works on 'both twigs and roots, thus there is a subterranean as well as an : . aerial form. 3?rom this fact this . t , , louse, like the notorious phylloxera, ' . is one of the worst speci mens of its most pernicious family. The woolly secretion, however, is in . ; our favor, for it reveals the louse .' , on the trunk and also in the earth. "We 'dig the fine, liberous roots many feet away from tho trunk and the plainly visible cotton-like fibers tell that the foe is there. These miniate lice, scarcely visible without a glass, cften rest in groups of ' three or more on the rootle ts, and siwk the very life from the trees. As with the grape phylloxera, the roots become knotted knott-ed or produce galls, which also reveal the presence of the foe, and show that ruiu threatens the .orchard. In a recent visit to the. large, magnificent pear orchards on the Sacramento river, I found many of the trees showing diseases. Upon . examination, 1 found on the roots everywhere, even to the utmost these wee sappers. On examination examina-tion I found the same true even on the. trees not yet showing disease, though the lice were , not yet so abundant on apple trees hard by, the lice Were common on the twigs. , . The root lice on the pears seem less woolly than those on the twigs, and the roots seem little knotted, though I found some of the galls. My friend, Mi. Craw, thinks from this that it is another ; species. I am inclined to think t tat the variation d because of ' region and plant, and is not specific Prof. A. J. Cook in California Cal-ifornia Cultivator. |