I have found this minute and destructive insect on my pear trees as late as the middle of December, the imperfect insect or pupa still busily employed in sucking the sap by means of its rostrum or piercer, (which is situated under the thorax,) and at the same time discharging its excrement, which is the honey-dew, or sweet glutinous substance so plentifully adhering to and disfiguriug the branches at present Other insects - the aphis, for example - have also the power of producing the honey-dew; but of this we will speak hereafter. Ants are said to be very fond of it, and this may account for the multitudes of these restless and proverbially industrious insects I have often observed running up and down a feeble and diseased pear tree this season. The pupa of the Psylla pyri at this time of the year appears to prefer the side of a branch, just above a bud, as its permanent place of residence, as it perhaps finds the sap more abundant there. The head is generally hidden under the bud, leaving merely the black abdomen and wing-cases visible, although they sometimes quit this quiet shelter and promenade on the branch, probably in search of better quarters.

When taken from the tree, they crawl very slowly, and their general appearance puts one forcibly in mind of that species of insect which is such a terror to all cleanly housewives, and which generally performs its annual migrations in the city of New York "on or about" the first of May. The pupa of the Psylla pyri is very minute, and of a flat shape. The wing-cases and abdomen now are black, but I must here remark that the colors are said to vary in spring and summer. The legs are six in number, and of a yellowish brown color, growing darker or nearly black toward the tarsi or feet, which appear to terminate abruptly and to have no joints. The eyes are reddish and prominent, like those of the locust, (Cicada.) The head is black, with a yellowish red longitudinal stripe. Thorax same, yellowish red, spotted with black. Four first segments of abdomen black, ringed with yellowish red. Extremity or tail broad, black, and fringed with hair. I likewise discovered on the same branch a cluster of very minute, reddish eggs, placed on and underneath a bud, and which probably belong to the Psylla. The perfect insect has four wings, which, when folded together, form an angle like the roof of a house.

These wings are transparent, veined with black, and with a black spot or mark on the lower side of the upper wings. The under wings are partly edged with black, and have only one black rib near the center. The head (which is divided in the center, and has two projections in front,) and thorax are dark brown, striped and spotted with dirty yellow. Eyes prominent, and reddish. Abdomen black, banded with yellow. Legs yellowish. Antennae long, and apparently jointed. Tail divided, black, and turned up. The perfect fly generally walks with the greatest gravity and decorum; but on presenting the finger, and when you least expect it, he disappears with a spring like a grasshopper, using his wings at the same time; and it was some little time before I could capture a perfect specimen to sketch from. They likewise appear to be of a very sociable disposition, as groups of twelve or more may be found on the branches, huddled together like sheep, and each one apparently on the best possible terms with his neighbor. After my thermometer had been to 7 deg. Fahr., I found several perfect insects hidden under the rough bark of a pear tree, and which, on being placed in my hand, became " thawed out" and quite lively.

The greatest wonder is how the larvae elaborate honey-dew in such great quantities, as I have seen a drop exuding from the body of one (perhaps the gormandizer of his race) six or eight times as large as the insect itself. Indeed, it was only from the appearance of this dew that I was at first induced to examine a branch. No doubt this constant drainage of sap must impair the vital energy of the tree, and in time would so much weaken it as to impair its fruitfulness, if not altogether kill it.

PSYLLA PYRI.

The insect being found, the next question is how to get rid of it.* Whale oil soap with a little flour of sulphur is excellent for most insects, and I think would answer the purpose here. I have often seen the little chickadee, or black-cap titmouse, clinging to my pear trees, head up or down as the case might be, peering inquisitively into such nooks and corners as the Psylla pupa) frequent, and then making a most suspicious dart with his short and sharp bill. I have no doubt that he often swallows a dozen or so as a relish, as we eat oysters, although it would require a great many Psyllae to make even a tolerable lunch for a chickadee.

In regard to birds, with all due deference be it spoken, I am of a very different opinion to the anti-ornithological correspondent of the Horticulturist, and will merely mention one fact among the many I have experienced, in corroboration of my opinion. A king bird, or tyrant fly-catcher, having made rather too free with the lives and liberties of my bees, (or, as some say, only drones, though this fact has never been proved to my satisfaction,) I shot an unfortunate little phoebe bird, as it was sitting amidst the foliage of the tree the king bird was accustomed to frequent. So much for keeping bad company, I moralized, and immediately proceeded to dissect it, in order to see if I had not done right in shooting it, also hoping to find one bee at least in its stomach, as a sort of salvo to my conscience for committing this foul murder, when to my astonishment and regret I found it completely full of the Galereuca vittata, or striped bug, so injurious in this country to the young cucumber and melon plants.

I think I need not add that I never shot another, but now encourage all the insectiverous birds to build their nests on my place, by every means in my power; and I really believe that I have already received ample repayment for any little protection I am able to afford them, by the sensible diminution of insects in my garden, not to mention the gratification I receive from the sweet songs of the blue bird, wren, garden warbler, etc., who serve to enliven many a long summer's day from sunrise to sunset. G. - Fishkill, N. Y.

* We succeed quite well in destroying the common green and black aphis on trees, with a solution of tobacco. We pot some tobacco stems into a barrel-say half fill it-and then fill up with water. After a few days soaking it is fit tor use. We keep this very effectual remedy at hand during the whole growing season. It would be very well to add a little whale oil soap. We think this will destroy the Psylla especially if pretty strong.-Ed.