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The Hessian Fly

Brought forward 909,120 2. The second eighth, or the forty females of the second brood, lay three times, the produce of which is.. 9,600 One sixth of these, or 1,600 females, three times.... 384,000 The second sixth, twice 256,000 The third sixth, once .. 128,000 3. The third eighth, or the forty females of the third brood, lay twice, and produce.... 6,400 One fourth of these, or 1,600 females, lay twice 256,000 more 4. The fourth eighth, or forty females of the fourth brood, once Half of these, or 1,600 females, at least once ...... 3,200 128,000 Total produce of a single fly, in one summer....2,080,320 Another curious insect is, THE HESSIAN FLY. - This is a very mischievous insect, which a few years ago appeared in North America, and whose depredations threatened then to destroy the crops of wheat in that country entirely. It is, in its perfect state, a small winged insect, but the mischief it does, is while in the form of a caterpillar; and the difficulty of destroying it is increased, by its being as yet unknown where it deposits its eggs, to be hatched before the first appearance of the caterpillars. These mischievous insects begin their depredations in autumn, as soon as the wheat begins to shoot up through the ground. They devour the tender leaf and stem with great voracity, and continue to do so till stopped by the frost; but no sooner is this obstacle removed by the warmth of the spring, than the fly appears again, laying its eggs now, as has been supposed, upon the stems of the wheat just beginning to spire. The caterpillars hatched from these eggs, perforate the stems of the remaining plants at the joints, and lodge themselves in the hollow within the corn, which shews no sign of disease till the ears begin to turn heavy. The stems then break, and being no longer able to perform their office in supporting and supplying the ears with nourishment, the corn perishes about the time that it goes into a milky state. These insects attack also rye, barley, and timothy-grass, though they seem to prefer wheat. The destruction occasioned by them, is described in the American Museum, (published at Philadelphia,) for Feb. 1787, in the following words :- "It is well known that all the crops of wheat in all the land over which it has extended, have fallen before it, and that the farmers beyond it dread its approach: the prospect is. that unless means are discovered to prevent its progress, the whole continent will be overrun;-a calamity more to be dreaded, than the ravages of war." This terrible insect appeared first in Long Island, during the American war, and was supposed to have been brought from Germany by the Hessians; whence its name. From thence it proceeded inland at the rate of about fifteen or twenty miles annually; and, in 1789, had reached two hundred miles from the place where it was first observed. At that time it continued to proceed with unabating increase; being apparently stopped neither by rivers nor mountains. In the fly state it is likewise exceedingly troublesome, by getting into houses in swarms, falling into victuals and drink, filling the windows, and flying perpetually into the candles.

THE MAY FLY. -This insect is called the May fly, from its annual appearance in that month. It lies all the year, except a few days, at the bottom or sides of rivers, nearly resembling the nymph of the small libella; but when it is mature, it rises up to the surface of the water, and splits open its case; then, with great agility, up springs the new animal, having a slender body, with four black-veined, transparent, shining wings, with four black spots in the upper wings; the under wings are much smaller than the upper ones; and with three long hairs in its tail.

The husk it leaves behind floats upon the water. After this creature is discharged from the water, it flies about to find a proper place to fix on, (as trees, bushes, &c.) to wait for its approaching change, which is effected in two or three days.

The first hint I received of this wonderful operation, was by seeing their exuviæ hanging on a hedge. I then collected a great many, and put them into boxes; and by strictly observing them, I could tell when they were ready for this surprising change.

I had the pleasure to shew my friends one, which I held in my fingers all the time it performed this great work; it was surprising to see how easily the back part of the fly split open, and produced the astonishing transformation. In the new fly, a remarkable difference is seen in their sexes, which is not so easy to be perceived in their first state, the male and female being much of a size; but afterwards the male is much the smallest, and the hairs of their tails much the longest.

When the females are about to deposit their eggs, they seek the rivers, keeping constantly playing up and down upon the water. It is very plainly seen, that every time they dart down, they eject a cluster of eggs, which appears like a little