Plant-Louse, Puceron, or Vine-fretter, Aphis, L. a genus of insects, comprising many species and varieties, all of which are denominated from the plants they infest. Their rostra or beaks are inflected ; they are provided with four erect wings; and the abdomen terminates in two horns, whence the juice, known under the name of Honey-dew, is said to be ejected

These insects are extremely prolific, depositing their eggs on the buds, leaves, and even the stems of plants ; into which they thrust their minute beaks, and thus extract their sustenance.—As the vine-fretters are uncommonly numerous, these punctures, being continually repeated, disfigure the leaves, and otherwise materially injure the plant. Various means have therefore been contrived, with a view to prevent their depredations, and to extirpate these vermin.—Under the articles Insects, and Pink, we have already stated the most successful methods practised by gardeners for this purpose : hence, we shall only observe, that such insects appear to be generated chiefly by an improper management both of the soil and plants ; namely, by employing crude manure, whether of animal or vegetable substances, not sufficiently putrified ; by the use of' stimulating liquids, such as bullock's blood, the water collected from farmyards, and similar preparations ; by the want of fresh air, or by excluding the young plants from the benefit of the dew, and the solar rays :—for it has been remarked, that vegetables, constantly exposed to the influence of the atmosphere, are not liable to be materially injured by plant-lice.

Plant-Louse.- - These vermin are very detrimental to trees, by devouring both their foliage and fruit: hence, they ought to be exterminated at an early period of their existence. - Mr. Forsyth recommends two parts of fine wood-ashes to be mixed with one part of unslacked lime, reduced to powder; which must be thrown on the under-side of the leaves infested with the insects, by means of a common dredging-box, till they are completely covered. This mixture should be applied early in the morning, before the dew is evaporated, that the powder may adhere more firmly; and which must farther be suffered to remain on the leaves, for three or four days.

Unslacked lime is then to. be incorporated with soft water, in the proportion of half a peck to 32 gallons; and the mixture stirred two or three times in 24 hours, for three or four successive days. After the lime has subsided, the trees must be copiously watered with this liquid; care being taken to throw a considerable part of it on the lower side of the leaves. The irrigation must be repeated once every day, for a week; a practice by which the plant-lice will be effectually destroyed.