This species of insect is named ephemeral, because of its very short existence in the fly state. It is one of the most beautiful species of flies, and undergoes five changes. At first, the egg contains its vital principle ; it comes forth a small caterpillar, which is transformed into a chrysalis, then into a nympha, and lastly, into a fly, which deposits its eggs upon the surface of water, where the sun's rays bring them to life. Each egg produces a little red worm, which moves in a serpentine manner. They are found in abundance during the summer, in ponds and marshes; and as soon as cold weather sets in, the little worm makes for itself a shell or lodging, where it passes the winter; at the end of which it ceases to be a worm, and enters into its third state, that of a chrysalis. It then sleeps till spring, and gradually becomes a beautiful nympha, or a sort of mummy, something in the form of a fish. At the time of its metamorphosis, the nympha at first seems inactive and lifeless; in six days, the head appears, raising itself gradually above the surface of the water; the body next disengages itself slowly and by degrees, till at length the whole animal comes out of its shell. The newborn fly remains for some minutes motionless upon the water, then gradually revives, and feebly shakes its wings, then moves them quicker, and attempts first to walk, then to fly. As these insects are all hatched nearly at the same time, they are seen in swarms for a few hours flitting and playing upon the surface of the water; they then lay their eggs, and soon after die. Thus they terminate their short life in the space of a few hours, and the same day that saw them born, witnesses their death,