Adult mayflies are slender, soft-bodied, with four membranous, extensively veined wings held upright and together (like a butterfly). The forewings are much longer and often overlap the hindwings. When perching, the front pair of legs are often held outward. They have short antennae and large compound eyes. There are 2 long, threadlike cerci (antenna-like appendages extending from the tip of the abdomen).
The naiads (nymphs) are aquatic and somewhat resemble the adults, though they lack wings, have a series of leaflike or feathery external gills attached along the sides or on the top rear portion of the abdomen, have smaller eyes and often have a flattened head that helps them to adhere to rocks in fast-flowing water. Nymphs possess 3 (sometimes 2) long cerci extending from the tip of the abdomen.
Habitat and Conservation
Usually found near water.
The name of the order, Ephemeroptera, is from Greek words for “short-lived” (as in “ephemeral”) and “wing” (the “-optera” part). It’s a good name, because as winged adults, mayflies only live a few days. The adults’ only function is to reproduce.
The swarms of adult mayflies often provoke feeding frenzies among fish.
The nymphs (or naiads) play important roles in aquatic ecosystems, eating algae and other small items and being eaten by larger animals.
Different species of mayflies eat different things in their aquatic immature stages, but most creep around on rocks in lakes, ponds, streams, or at river edges, eating algae and other small plants.
Once they float up to the surface and molt into a winged adult, they have only vestigial (remnant) mouthparts and cannot eat or drink.