1638. The Ephemerï¾µ;, or May flies, are not numerous or in great abundance in this country; the largest is the E. vulgata (fig. 283. b): the under wings in this family are generally very small; and Harris figures a species (Exposition of Eng. Ins., pl. 6. f. 1.3.) wherein they could not be detected, even with the assistance of a strong magnifier. The duration of the lives of these insects in their various states is most unequal, and deserves particular notice. They remain as larvï¾µ for three years; when ready to become winged, they rise to the surface of the water, and instantaneously throwing off their cases, the metamorphosis is at once accomplished. The insect is then furnished with wings, with which it immediately flies to some convenient place; it then (unlike all other insects which have attained the winged state) throws off a second skin, and in the same moment becomes a perfect ephemera. In this state all the species live but a very short time, some scarcely half an hour, during which time they consummate their nuptials, and the females deposit their eggs. M. Reaumur has given us a most interesting account of a species so abundant in France and Carniola, that the peasants collect them in carts for manure, and frequently twenty-five or thirty of these loads are gathered-in one season. After many curious details, M. Reaumur goes on to describe the appearance of these insects on the banks of the river, near his residence, in August, 1738. 'The quantity of ephemerï¾µ which filled the air can neither be expressed nor conceived. When snow falls thickest, and in the largest flakes, the air is never so completely filled with them, as that which surrounded us was with ephemerï¾µ. Scarcely had I remained a few minutes in one place, when the step on which I stood was covered in every part with their bodies to the depth of two or three, and in some places even to more than four inches. The whole surface of the water, for six feet at least from the bank, was entirely covered with a coat of ephemerï¾µ; those which the current carried off were more than replaced by those which fell continually in that place. I was several times obliged to abandon my station, by retreating to the top of the stair, not being able to sustain the shower of ephemerï¾µ, which, not falling perpendicularly, or with an obliquity equally constant, struck me uninterruptedly, and in a very troublesome manner, on all parts of the face. At the end of about half an hour from its commencement, the great shower began to abate; and, in little more than an hour, scarcely any [living] ephemerï¾µ could be seen.'