MAY FLY. An insect of the order Epheme rida, sometimes also called `shad-fly' and 'day fly,' the latter, like the scientific name, derived from the ephemeral life of the adult. They have short antennie, very large fore wings, very small hind wings. absolutely trophied mouth-parts. and two or three long, slender filaments at the end of the abdomen. The transformations are com plete, and the early stages are passed in the water. The larve are active, possess long and strong legs, and breathe by means of tracheal gills. They are found under stones in running streams or swimming among water plants in quiet waters, or they may live at the bottom, more or less covered with slime or mud; some forms also burrow into the sand banks of rivers. They both swim and crawl, and they feed largely upon vegetable matter. The pupa or nymph is also active and feeds. It has small wing-pads, and when ready to transform it floats at the surface of the water and the subimago issues through the skin of time thorax. The emergence is very rapid, and the subimago flies away almost immediately after the skin cracks, The existence of a subimago stage is peculiar to this order of insects, and there is a subsequent molt a fter the subimago reaches the shore, the true imago issuing from the skin of the subimago. The May
flies differ from all other insects not only in this additional transformation. but also in possessing paired sexual organs which open to the exterior by separate orifices. The life of the adult insect is very short, but the popular idea that they live but a day is erroneous. Curtis kept one alive three weeks. Most species couple during flight, and egg-laying is usually performed in fresh Water, where the egg clusters disintegrate and the eggs sink to the beds of the rivers and streams. The larval life lasts from one to three years, and the larvir form a favorite food for many food-fishes. The adults are also eagerly sought for by fish, and many of the artificial flies, especially those forms known as 'duns,' `drakes,' and 'spinners' (see FLY-CASTING), are imitations of May flies. About 300 species have been described-85 from temperate North Amer ica. They are strongly attracted to light and fly in enormous numbers, so that they sometimes half fill the globes of electric street lamps with their bodies in a single evening, and greatly trouble lighthouse keepers, especially along the Great Lakes. by swarming about time lantern in such crowds as to obscure the light.