Mayflies, Order Ephemeroptera

Habits and Traits of Mayflies

Mayfly. Getty Images/Oxford Scientific/Photodisc

The order Ephemeroptera includes only the mayflies. Ephemeroptera comes from the Greek ephemeros, meaning short-lived, and pteron, meaning wing. Adult mayflies live just one or two days.


As adults, mayflies have delicate, slender bodies. They hold their membranous wings vertically when at rest. You can easily identify an adult mayfly by its triangular forewings and two or three long, threadlike tails extending from the abdomen. Most species also produce a subimago stage, which looks similar to the adult but is sexually immature.

Mayflies live on land as adults, but are entirely aquatic as nymphs. Adult mayflies live just long enough to mate, which they often do in dramatic swarming flights. Receptive females fly into the cloud of swarming males, and mate in flight. The female deposits her eggs on the surface of a shallow pond or stream, or on objects in the water.

Mayfly nymphs inhabit streams and ponds, where they feed on algae and detritus. Depending on the species, a mayfly nymph may live two weeks to two years before emerging from the water to complete its life cycle. Mayflies are known for emerging en masse, usually in May. In some places, large numbers of emerged mayflies can coat roads, making travel slippery and dangerous.

Habitat and Distribution

Mayfly nymphs inhabit fast-flowing streams and shallow ponds with high levels of dissolved oxygen and low levels of pollutants. They serve as bioindicators of good water quality. Mayfly adults live on land, near ponds and streams. Scientists describe over 4,000 species worldwide.

Major Families in the Order

  • Family Baetidae - small minnow mayflies
  • Family Heptageniidae - stream mayflies
  • Family Ephemeridae - common burrower mayflies
  • Family Leptophlebiidae – prong-gilled mayflies
  • Family Siphlonuridae - primitive minnow mayflies

Families and Genera of Interest

  • The American sand burrowing mayfly, Dolania Americana, is one of a few species of predatory mayflies.
  • The Gila mayfly, Lachlania dencyanna, is known to exist only in one small area of New Mexico, and is threatened with extinction.
  • An unusual parthenogenetic mayfly, Eurylophella oviruptis, employs a surprising method of oviposition. The subimago's abdomen literally ruptures, spilling its eggs onto the water's surface.


  • Borror and DeLong's Introduction to the Study of Insects, 7th Edition, Charles A. Triplehorn and Norman F. Johnson
  • Order Ephemeroptera - Mayflies,
  • Guide to Aquatic Insects and Crustaceans, Izaak Walton League of America