but also to furnish materials for a few observations, tending to lead to the means of lefsening the evils that result from the operations of this and some other insects: for it is by observing facts alone, and reasoning upon them, that any good can ever result from this department of science.

There is a disease which every person who has adverted to the progrefs of trees, particularly fruit trees, must have often heard of, as well as seen the effects that are attributed to it. It is called blight; a word so familiar, that people do not seem to give themselves the trouble to inquire what it means. If you ask a gardener What is a blight,—he will tell you it is a something, that every body knows, which affects the health of trees. When you prefs him to say what is the cause of it, he knows not, only he thinks it comes from some particular affection of the air; and that a common consequence of it is, a shrivelling up of the leaves, very often accompanied with swarms of diminutive insects, or an incrustation of a whitish powder over all the leaves. In short, it is a convenient term among gardeners, like that of nervous among physicians, to give an appearance of knowledge respecting those cases of which they know nothing.

Without pretending to say positively, that a particular state of the atmosphere may not produce certain diseases on plants, especially when the changes from heat to cold have been great and sudden, it may with safety be afserted, that, perhaps ninety-nine times out of a hundred, those diseases called blights are the consequence of the ravages of insects, and not the cause of it. And were a proper degree of attention to be

given to the transformations and habits of the insects that swarm in our gardens, these blights might be entirely obviated: of this, the history of the insect now under consideration will afford a very satisfactory proof.

Nothing is more common than to see a peach-tree which shows a fair blofsom; but before the leaves come out, the points of the twigs appear dark and discoloured; the leaves come out sickly; the blossom falls, or the fruit that sets drops off when it has made a small progrefs; even the leaves sometimes drop off entirely, and it appears as bare towards the beginning of May as it was at Christmas. This has all been occasioned by a blight. It then begins to recover a little, and before the middle of June puts out a fresh set of leaves; it begins to push forth its tender shoots, and afsumes a most promising appearance; but by and by a cruel blight, that has been produced by some inauspicious haze, again attacks the ill-fated tree, the effects of which are plainly perceptible by the leaves being all covered over with a whitish powder like hoar frost, in consequence of which severe shock they are arrested in their progrefs, and never through the whole season recover the effects of it.

Such are the facts, and such the explanation of them that is usually given. The conclusion is, that, as men can have no influence in regulating the changes of the atmosphere, it exceeds our power to ward off the disease; and nothing remains for us to do but to submit contentedly to the will of Heaven. If, however, we take the trouble to ascertain the real facts in this case,

but also to furnish materials for a few observations, tending to lead to the means of lefsening the evils that result from the operations of this and some other insects: for it is by observing facts alone, and reasoning upon them, that any good can ever result from this department of science.

There is a disease which every person who has adverted to the progrefs of trees, particularly fruit trees, must have often heard of, as well as seen the effects that are attributed to it. It is called blight; a word so familiar, that people do not seem to give themselves the trouble to inquire what it means. If you ask a gardener What is a blight,—he will tell you it is a something, that every body knows, which affects the health of trees. When you prefs him to say what is the cause of it, he knows not, only he thinks it comes from some particular affection of the air; and that a common consequence of it is, a shrivelling up of the leaves, very often accompanied with swarms of diminutive insects, or an incrustation of a whitish powder over all the leaves. In short, it is a convenient term among gardeners, like that of nervous among physicians, to give an appearance of knowledge respecting those cases of which they know nothing.

Without pretending to say positively, that a particular state of the atmosphere may not produce certain diseases on plants, especially when the changes from heat to cold have been great and sudden, it may with safety be afserted, that, perhaps ninety-nine times out of a hundred, those diseases called blights are the consequence of the ravages of insects, and not the cause of it. And were a proper degree of attention to be

given to the transformations and habits of the insects that swarm in our gardens, these blights might be entirely obviated: of this, the history of the insect now under consideration will afford a very satisfactory proof.

Nothing is more common than to see a peach-tree which shows a fair blofsom; but before the leaves come out, the points of the twigs appear dark and discoloured; the leaves come out sickly; the blossom falls, or the fruit that sets drops off when it has made a small progress; even the leaves sometimes drop off entirely, and it appears as bare towards the beginning of May as it was at Christmas. This has all been occasioned by a blight. It then begins to recover a little, and before the middle of June puts out a fresh set of leaves; it begins to push forth its tender shoots, and assumes a most promising appearance; but by and by a cruel blight, that has been produced by some inauspicious haze, again attacks the ill-fated tree, the effects of which are plainly perceptible by the leaves being all covered over with a whitish powder like hoar frost, in consequence of which severe shock they are arrested in their progrefs, and never through the whole season recover the effects of it.

Such are the facts, and such the explanation of them that is usually given. The conclusion is, that, as men can have no influence in regulating the changes of the atmosphere, it exceeds our power to ward off the disease; and nothing remains for us to do but to submit contentedly to the will of Heaven. If, however, we take the trouble to ascertain the real facts in this case,

The young shoots at the beginning of the season are sullied by immense crowds of the coccus that I have above described, which had been bred on the same tree during the former season, and been suffered to increase without molestation. In consequence of the numerous issues for the sap that are opened by the insects, not only that which goes to sustain them, but that also which (perhaps in greater quantities) falls among the leaves and is difsipated, the tree becomes sickly. As the insects increase in size, and come nearer to maturity, their operations are more powerful, and it becomes almost wholly exhausted; so that the leaves sometimes fall off entirely. No sooner, however, do these insects give over eating, previous to going into their nymph state, than these drains are suffered to dry up, and the plant begins to acquire some vigour. None of the males after this requiring any food, and it being uncertain whether even the females, while in the state of gestation, require any, the sap, now allowed to resume its usual course, produces its natural effect by pushing forth leaves and shoots, which go forward in their course till the young fry are hatched, and have acquired strength to go about in search of food. They now disperse themselves in myriads all over the parent tree where they have been hatched. Nothing can be more suitable for their use than the tender leaves upon it that have so lately been produced there. They fix themselves upon these leaves in multitudes, where they remain immoveable in the form of that powder above described, which upon a near examination is found to be more like to those small scales sometimes generated among the hair of