Mayflies are an ancient lineage of winged insects. The scientific name, Ephemeroptera (εφήμερος = for a day, πτερον = wing), refers to the short lifespan of adults in this group. Once they have completed their final molt, mayflies live only long enough to mate and reproduce, from a few hours in some species to a few days in others. Immature mayflies, called nymphs or naiads, live from a few weeks to a year or two under water in ponds and streams. Mayflies are unique among living insect orders in having a winged, immature stage, the subimago, which emerges from the water and thenmolts again after a brief period into the final reproductive adult or imago. Since adult mayflies live for such a short time, the emergence of males and females must be closely synchronized which can lead to huge swarms of freshly emerged imagos in some areas.
Mayfly nymphs are important members of aquatic food webs. Most feed on algae and detritus, although a few species are predaceous. Many fishes and other freshwater animals depend on mayfly nymphs as a major food source. Since mayflies are also very sensitive to changes in water chemistry, they are often used as indicators of water quality.
Mayflies have 41 families with about 2, 500 species around the world. Twenty-three families and 631 species are in North America.
Mayflies are aquatic insects that spend most of their lives in or around lakes or streams. Mayflies are unique because they are “the only insects where a winged form undergoes molting” (Wikipedia, 2013).They have three stages of development.The naiads (or nymphs) emerge from their eggs and find algae to eat.The naiads have gills on their abdomen.They represent incomplete metamorphosis.Within this stage they molt a few times over the course of a few months to a year.Their last molt brings them into the next stage called the subimago.The subimago is characterized by the addition of wings.The subimago molts one more time to the fully-fledged adult form called the imago. The abdomen of the imago is separated into ten segments. The imago are only concerned with reproduction. They do not eat during this stage.They usually live for a day or two.The mayflies will swarm over water in order to find mates.Oviposition occurs from a few minutes to a few hours after mating.Females lay their eggs on the surface of the water and the eggs sink to the bottom.
