Quick Facts

Species Type



Up to 20 mm not including antennae and caudal filaments


Aquatic in the nymphal stage; adults are terrestrial; nymphs are found in a variety of freshwater habitats including lakes, ponds, wetlands, streams and rivers


Nymphs scrap periphyton (layer of algae and associated fauna and flora)


Most adult mayflies only live between one and four days

Conservation Status



Winged mayflies have large compound eyes, short, bristlelike antennae, and functionless mouthparts and digestive tracts. Their membranous wings include a large, triangular front pair and a much smaller, rounded hind pair. In a few species, the hind pair is extremely reduced or absent.


Some species are carnivorous, but the majority of nymphs feed on algae, higher plants, and organic decaying material. Nymphs are devoured in turn by many carnivorous animals, especially fishes.


Mayfly eggs are eaten by snails and by caddisfly larvae. The nymphs may be eaten by fish, frogs, birds, flies, or water beetles.

Reproduction and Life Cycle

Mayflies undergo incomplete metamorphosis. Their life cycle includes four stages – egg, nymph, subimago and adult (imago). Most species produce one or two generations per year.

Did You Know?

  • Other common names for the winged stages are shadfly, sandfly, dayfly, fishfly, and drake.
  • The aquatic immature stage, called a nymph or naiad, is widely distributed in freshwater, although a few species can tolerate the brackish water of marine estuaries.
  • The existence of mayflies in a stream is a good indicator of water quality.

Sources and Additional Information