Mayflies are part of the first insect order that has wings, Ephemeroptera. They are larger than the prior insect orders, Protura, Thysanura, and Collembola. They have large, triangular fore wings and small, rounded hind wings. At the end of their abdomens, they have 2 or 3 long, hair-like tails.

Mayflies in both their adult and nymph state are an important food for many freshwater wish. Because of this, fishermen ofter use flies that look like Mayflies.

Mayflies begin their lives in the water, then come out of the water as they molt. Once they reach their adult stage, they seldom live for more than a day or two.

Order Ephemeroptera is divided into three different suborders, which are seperated by the pattern of veins on their wings and their tarsal segments.