Mr. Downing - Dear Sir: I send you an account of the method I have successfully practiced during eight years, in protecting my plums from the depredations of the cur-culio.

I will first mention some facts relative to the habits and natural history of that destructive insect, the knowledge of which I acquired, part by observation, and partly by reading an article on insects from the pen of the lamented Willis Gat lord.

Generally, as soon as the plum has attained the size of a full grown currant, the curcu-lio ascends [or flies to, Ed.] the tree, and, making a semilunar puncture in the plum, deposits an egg in it; commonly only one egg is deposited in a plum, but sometimes two eggs are found in the same plum. These eggs become larvae or grubs, that feed on the pulp of the plum, which finally causes the plum to fall to the ground before it is ripe. After the maggot or larvae, as the embryo insect is frequently called, attains a sufficient size, it crawls out of the plum, goes into the earth, stays there about twenty-one days, and comes out a perfect insect. These new insects ascend the tree, either by climbing or flying, puncture the plums and deposit their eggs.

Of the plums until they fall to the ground, and, when they have attained the proper size, they crawl out of the plum, go into the earth, stay there their allotted time, twenty-one days, become perfect insects, come out of the earth, ascend the trees and perform the same destructive operations that their predecessors did. Thus we perceived that several generations of that most destructive pest, to stone fruits generally, are produced in one season.

Reflecting on these facts, I concluded that if we would destroy the insects in their embryo state, we should preserve our stone fruits from their depredations. I made the experiment; and its success exceeded my most sanguine expectation; for, instead of from half a dozen to a dozen ripe plums, my usual annual crop from one tree, I had three measured (not estimated,) bushels, and I had that amount annually from one tree, until it was destroyed by the disastrous fire that laid waste our village in the autumn of 1849.

Early in the spring I remove all grass and weeds from the vicinity of the trees; I then level and smooth the surface of the ground around the trees, and make it as hard as I can, by beating it with the surface of a spade or hoe. It is then prepared for being easily swept with a common broom. As soon as the young plums attain the size of a full grown currant, I shake the trees with some violence early in the morning. - early because the curcu-lio is somewhat torpid then in consequence of the coldness of the night, and it is therefore more easily detached from the tree; I then collect, by sweeping, everything that falls from the tree, whether insects or plums, and commit the sweepings to the flames or throw them into boiling water, and by that means destroy both the insects and their embryos. If the punctured plums are thrown into cold water, the insects are hatched, about as readily, as if they were suffered to lie on the ground, as I have witnessed in several instances. It is necessary to continue this shaking and sweeping and burning daily, until the plums are ripe. When the ground around the trees is properly prepared for sweeping, as above mentioned, it requires less than five minutes each day to shake three trees, sweep, and commit to the flames the collected sweepings.

The time was measured, not estimated. If the ground around the trees is closely covered with flat stones, bricks or boards, the fruit is effectually protected from destruction by the curculio, unless that pest is suffered to breed in the vicinity. The punctured plums should not be permitted to lie long on the ground, lest the embryo insect should crawl out and go into the earth. The above statements can be relied on; they are facts deduced from actual practice. I think we may justly conclude from them, that a proper concert of action, on the part of the owners of stone fruit trees, would effectually preserve our plums from the devastations of the curculio.

The curculio sometimes feeds on ripe plums, but more commonly, I believe, on the succulent and tender extremity of the branches near the terminal bud. It frequently bites off the terminal bud of the leading shoot. After it has fed, it conceals itself on the under surface of a leaf, where it usually spends the day, unless the day is cloudy and dark. I believe it moves about more during the night than during the day. I do not know what becomes of it on the approach of cold weather. I think it hybernates in the earth. I have seen it go into the crevices of the ground.

I have made some efforts to discover the insect that causes the excrescences which destroy so many plum and cherry trees, but, thus far, my efforts have been unavailing. I have tried to hatch the larvae in the house, but soon after the limbs, containing the exeresis more likely, after the nutriment has been elaborated by the appropriate organs, the fibrous texture is destroyed to such a degree that the elaborated nutriment can not be carried through the proper vessels to its destined places, and the tree therefore dies. The excrescence insect seems to prefer the morello cherry tree to any other tree. I have seen that tree, standing among young and vigorous plum trees, destroyed, while the plum trees remained untouched.

I have been acquainted with the wild plum tree for nearly half of a century, and I do not remember to have seen an excrescence on any of them. The curculio generally destroys its fruit. A gall insect often preys on the wild plum and wild cherry also, converting both the plum and the cherry into large, irregular bladder-like masses. The wild plum tree does not grow so fast as the cultivated plum tree, but is much longer lived. I have seen them more than a foot in diameter in this vicinity, and I think three quarters of a century old. The cultivated plum, inocculated or ingrafted into the wild stock, grows well. I recently measured a thorn tree in this vicinity, sixteen inches in diameter. The apple tree ingrafted into the thorn, grows well here. Respectfully yours. 0.

Owego, N. Y., March, 1831.