The Apple-aphis (A. lanigera), sometimes called Ame• rican blight, which has of late proved exceedingly destruc tive to young apple-trees, first appeared in the neighbour hood of London only about the year 1795. It is a minute in sect covered with a long cotton-like wool ; it breeds in chinks and rugosities of the bark, and at length almost covers the infected tree. It is said that the application of the spirit of turpentine to the bark proves an effectual re medy ; and we know that it has been wholly banished from a garden where it had spread, by merely smearing the in fested branches with oil, as recommended by Sir George Mackenzie. Sir Joseph Banks extirpated it from his own apple-trees, by the simple means of removing all the rug ged old bark, and then scrubbing the trunk and hranches with a hard brush. Mr William Salisbury, in his " Hints to the Proprietors of Orchards," published in 1816, gives it as his opinion, that this is the same insect which has of late infested latch-trees. He supposes it to have been brought to this country by the Protestant refugees in the reign of Louis XIV. ; but he has assigned no reason for this extraordinary opinion, nor has he attempted to explain why so destructive an insect had lain dormant for so many years, and at length suddenly extended its ravages in so striking a manner. He observes, that Lorne of the insects descend during winter to the upper roots, and lodge there; in cleansing the trees, therefore, these should be examined, as well as the trunk and branches.
553. There are several distinct kinds of gooseberry-eater pillar. One species, of a whitish colour, becomes a longish fly, with golden-tinged wings, a yellow body, and yellow thighs ; probably the Tenthredo caprem. Another, of a greenish hue, which becomes T. flava, often proves quite destructive to the foliage of the plant, and consequently to the fruit. A third, of a larger size, and sometimes very common, is the larva of the magpie-moth (Phaleena grossu lariata, Lin. ?braxas of Leach. (The young of this last haunt during winter about the crevices of the bark ; and this is considered as the best time for destroying them. Their destruction may be effected merely by hard rubbing of the stems and branches, or by pouting boiling hot water over these parts, which at this season does not injure the bushes. The larva of the saw-flies or tenthredines pene trate about an inch tinder ground in July, and, passing into the chrysalis state, remain there till the following spring, when they come forth in the form of flies. For destroying these, one of the most effectual means consists in dek lug the ground about the bushes very deep during winter, tak ing care to bury the surface-soil in the bottom. In this way the chrysalids are placed beyond the genial influence of the atmosphere, or, if the transformation be accomplished, the fly is unable to gain the surface.
Different species of Coccus, particularly C. hesperidum, often called scaly insects, infest the plants of the green house and the conservatory, particularly the myrtle, the orange, and the olive. A thorough washing with soup and water, rubbing tire leaves with a woollen rag or bit of sponge tied un a small stick, is the remedy usually resort ed to, the plants being afterwards well syringed with pure water. Coccus vitis infests vines placed in stoves, and is often very injurious, covering their stems, as it were, with little tufts of white cotton. The means of freeing pine apple plants from the coccus have already been adverted to, § 223.
554. The red spider (?icarus telarius) infests not only the pine-stove, vinery, told melon frames, but often proves very injurious to ornamental stove plants. Water applied with the syringe is destructive to it. Some persons recommend the use of lime-water ; but it is not commonly employed, being found hurtful to the foliage ; nor does any addition to the water seem necess.l•y.
555. The finer kinds of fruits, as they approach ripeness, are subject to the attacks of different insects. Among these wasps (Vespa vulgaris) may be first mentioned. Va rious expedients are resorted to for destroying them. In some places, phials half filled with honey and water, or any sweet liquid, are hung in different parts of the tree ; and great numbers are thus ensnared. The most effectual means, however, of keeping down the numbers of this for midable enemy is, to destroy the females in the early par t of the season, and the nests in the autumn. From hot houses they are, in some places, excluded, by employing temporary doors and temporary frames below the sashes, covered with thin muslin or gauze : both kinds of doors arc never allowed to be open at the same time, and the gauze or muslin does not prevent the access of sufficient light and air. Where their exclusion is not thus effected, it is found very useful to have a plant of Hoya carnosa established. This is an ornamental climber (named in honour of Mr Thomas Hoy, a distinguished botanist, who has fur about half a century been head-gardener to the Duke of Nor thumberland at Syon House), and may be trained along any spare parts of the house. It flowers freely ; and as long as the blossotns continue, which they do for several weeks, the wasps give a decided preference to the sweet exudation they afford, leaving grapes and peaches untouched.
556.- Earwigs (Forficula auricularia) attack all sorts of ripe fruit. No remedy is known but ensnaring and killing them. Short cuts of reeds, or of strong wheat st•aw, or hollow stalks of any kind, are placed here and there among the branches, and also at the roots of the trees. Into these the earwigs take refuge in great numbers ; and from the tubes they are blown into a bottle containing water.