There are usually found in the month of June, especially near water, certain insects that are called Ephemera, and which long ago acquired true celebrity, and furnished material for comparison to poets and philosophers. Indeed, in the adult state they live but one day, a fact that has given them their name. They appear for a few hours, fluttering about in the rays of a sun whose setting they are not to see, as they live during the space of a single twilight only. These insects have very short antennæ, an imperfect mouth incapable of taking food, and delicate, gauze like wings, the posterior ones of which are always small, or even rudimentary or wanting. Their legs are very delicate--the anterior ones very long--and their abdomen terminates in two or three long articulated filaments. One character, which is unique among insects, is peculiar to Ephemerids; the adults issuing from the pupal envelope undergo still another moult in divesting themselves of a thin pellicle that covers the body, wings, and other appendages. This is what is called the _subimago_, and precedes the imago or perfect state of the insect. The short life of adult May-flies is, with most of them, passed in a continual state of agitation. They are seen rising vertically in a straight line, their long fore-legs stretched out like antennæ, and serving to balance the posterior part of the body and the filaments of the abdomen during flight. On reaching a certain height they allow themselves to descend, stretching out while doing so their long wings and tail, which then serve as a parachute. Then a rapid working of these organs suddenly changes the direction of the motion, and they begin to ascend again. Coupling takes place during these aerial dances. Soon afterward the females approach the surface of the water and lay therein their eggs, spreading them out the while with the caudal filaments, or else depositing them all together in one mass that falls to the bottom. These insects seek the light, and are attracted by an artificial one, describing concentric circles around it and finally falling into it and being burnt up. Their bodies on falling into the water constitute a food which is eagerly sought by fishes, and which is made use of by fishermen as a bait.