Economic entomology for the farmer and fruit-grower : and for use as a text-book in agricultural schools and colleges . leaves or twigs, beneath eachof which we find, how-ever, a great mass ofplant lice busily en-gaged in feeding. The alder ? blight andbeech-blight are dueto species of this kind,and more importantthan all is the apple-blight, or the woollyapple-louse. This spe-cies, Schizoneura lani-gera, has been intro-duced into other countries, and is known in England and Aus-tralia as the American blight. Young trees are frequentlyinjured by these aphids, which gather in masses on the trun
Economic entomology for the farmer and fruit-grower : and for use as a text-book in agricultural schools and colleges . leaves or twigs, beneath eachof which we find, how-ever, a great mass ofplant lice busily en-gaged in feeding. The alder ? blight andbeech-blight are dueto species of this kind,and more importantthan all is the apple-blight, or the woollyapple-louse. This spe-cies, Schizoneura lani-gera, has been intro-duced into other countries, and is known in England and Aus-tralia as the American blight. Young trees are frequentlyinjured by these aphids, which gather in masses on the trunks,and cause the death of the bark below the point of attack. Theeggs may be found singly in the bark ^^^- 98- crevices during win-ter, completely envel-oped in the dry skinof the female, andfrom them appear, inspring, agamic, wing-less forms, which bearliving young. Thismethod of reproduc-tion continues until thewinged type, whichspreads to other localities, is produced in late summer. Thesexed forms are wingless and mouthless, the female producingonly a single Qgg ; but in the southern parts of our country it. Schizoneura lanigfra. root form.—a, galls caused bythem on apple-roots ; b, wingless, wax-coated form ; form. 134 AN ECONOMIC ENTOMOLOGY. is not unusual for the insects to survive winter in the adult con-dition, without producing a winter &^^. One form of the speciesworks deep underground on the fibrous roots ; and this is mostdifficult to deal with, and often causes the death of the attackedtrees. When they appear on the trunk, treatment with eitherwhale-oil soap or kerosene emulsion will be effective, and theunderground form can be reached with bisulphide of carbon, orby a liberal use of the tobacco or kainit, as recommended on aprevious page. We have a number of species that attack our common orchardand farm crops, like the cherry-aphis, Myzus cerasi, the .peach-louse, Aphis persicae-niger, the apple-louse, Aphis 7nali, thehop-louse, wheat-louse, melon-lou
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