A. J. Downing. On my property near this city, I have a small young orchard of apple and peach trees, which early in the spring, gave promise of a fine crop of fruit. The trees are very thrifty, and are just beginning to bear. The apple trees, especially, look well, and every one had some fruit, and some of them were loaded. But an insect of the bug or beetle species has attacked my orchard, and I fear they will totally destroy the fruit, and seriously injure my trees.

About a week since was the first I observed of them. I then discovered a few of them on different trees, eating the tender leaves and young' apples. In the past week they have multiplied by thousands, and have commenced on my pencil trees, and even the vegetables in the garden. They have eaten up many of the leaves entirely, except the stem, and nearly all the apples. They commence by making a small incision in one side of the apple or peach, then eat the pulp, and increase in numbers-as the opening enlarges, until the fruit is entirely devoured. I have seen as many as 16 and 20 all crowding their heads into this opening, in the side of a small apple. The peaches suffer in the same way, but they like the apples much better.

When I discoved these insects, my first step was to consult my " books," see what they were, and what was the best method of destroying them. I have the works of Downing, Bar-rt and Thomas, all recent publications, and spe cially devoted to fruit trees, besides several other works that treat partly on the same subject, but in none of them could I find a description which would answer, as I thought, to this in* sect. I am a mere novice in the delightful study and art of fruit-growing, as yet, and could not tell any of the destructive insects except by comparing them with the descriptions in the books - which, by the way, I find entirely too brief and unsatisfactory for a learner like myself. (Query - What is the best work on this subject of "Insects ") [Harris' Treatise - now out of print - -but a new edition of which is in preparation. En].

This insect appears to resemble the locust more in its habits and ravages, than any other insect of which the books treat. But it is not near so large as the locust, and carries on its work of destruction in perfect silence. They fly about but little, and chiefly in the warmest part of the day. They continue pretty much in the same place, on the leaf or apple, during day and night. In the evenings and mornings they are more stiff and torpid. This induced me to try an experiment of catching them in a sheet early in the morning, when the dew is on the trees, and then killing them. We tried this plan, but after slaying our ten thousands, we gave it up as a hopeless job. I then tried syringing the trees most effectually with strong tobacco juice - but this seemed to have but littie, if any effect, upon then. This would never kill them, for I found they would lire after being immersed fire minutes in the juice. Even very strong brandy would net kill them for several minutes.

I herewith send-you some eight or ten of these insects, a part of what I took from one apple, that yon may see them, and give me any farther information yon may possess as to their nature, habits, etc., and the best mode of destroying them. If they are unknown to you, perhaps a brief nodes in the " Horticulturist" would elicit the desired information, or attract direct attention to the insect, if it should he found in other sections of the country. I be-Here it prevails to a greater or less extent in all the orchards in my neighborhood - how much further I have not learned. It is my intention to watch the insect closely, and learn more of its nature and habits.

The insects I send you were killed by being immersed in strong brandy. I will put them up in cotton, so that they may carry safely in my letter.

My ground is on the bank of the Ohio rirer, commonly called " bottom land,"-and is a deep, rich, sandy loam; but the trees on the river hill were also attacked.

Any information on this subject you can giro mo in a private letter, or in the Horticulturist, will be thankfully received. Tours, etc. J. N. F. W. Pitttburgh, Pa., June 19.

The insect sent us with the above is the rose-bug or rose-chafer, well known in some parts of the middle states, where the soil is light and sandy. It is the most difficult insect to destroy where it appears in abundance. In some vineyards on the lower part of the Hudson, infected with it, the only successful remedy yet found is to pick them by band, and put them in boiling water - an obviously hopeless task, when so abundant on trees as described by our correspondent. If any of our readers have found a more easy and speedy death for them, we shall be glad to hear from them. En.