Some mayflies live in the water a year or more before they become adults; many com­plete their growth in a few weeks. As a mayfly grows, wings develop inside the wing pads which you can see on his back. When he is fully developed, a fragile insect pushes his way out of the nymph skin and spreads his delicate wings to dry. Mayfly adults have two pairs of wings. The fore-wings are larger than the hindwings. When they are at rest, mayflies hold their wings high over their bodies. The adult's tails are much longer than those of the nymph from which it developed.

Although it may live in the water a year before it is fully grown, a mayfly lives in the air only a day or two. A short time after it emerges, the adult molts (sheds its skin) a second time. It cannot live very long be­cause it does not eat. Its mouthparts are useless.

At evening you may see hundreds of may­flies swarming over the surface of a pond or lake in their mating flight. After mating, the female lays eggs in the water. The long, slow development of eggs into nymphs and nymphs into adults begins again in the water, but the beautiful parents die.