Mayflies are divided into multiple families and are varied in color and pattern. They are the only insect known that molts while having wings; other insects molt into a winged form, their final life stage. Mayfly larvae are called naiads or nymphs, and they actually spend their lives underwater eating algae, organic matter, and debris found in their aquatic habitat. They look more like a tiny crustacean at this point. They have two, or possibly three 'tails' depending on the species, and gills allow them to breathe underwater. A year or more can be spent in this life stage, and molting occurs multiple times as the naiad grows in size. When it has matured, it molts into a winged pre-adult stage, and it is referred to as a subimago. The wings are a bit cloudy or smoky at this point, not fully clear, and the insect looks like a drab version of an adult. Those who fish call subimagos ‘duns’. Subimagoes leave the water assuming they avoid fish and avian predators. After this phase, the winged subimago molts again, and becomes a full-fledged adult called an imago, or a ‘spinner’ to anglers. Imagoes have very short life spans and do not eat. Males and females swarm in an aerial mating scene. Females lay fertilized eggs on the water’s surface below, or even under the water by crawling down into it to deposit eggs. Once this important task is complete, they die, falling into the water where they float on the surface. These dead mayflies become an easy buffet for hungry fish below. Trout fishermen observe this whole process in order to choose a lure that looks most like the mayflies present, and to time when to drop the bait into the water so it can be mistaken for a dead spinner. The hope is a great fish catch.
Mayfly naiads are great pollution police. They are very sensitive to chemical pollution and can only thrive in pristine water conditions. Areas where mayflies are present reflect clean water. Creeks, streams, and rivers that see annual swarms are consistently free of toxic chemicals, so such a sight is a good thing for the ecosystem. Swarms can be huge in such areas, and may be considered a nuisance to people that use the habitat for recreation, but their presence is brief so it is easily tolerated, especially since mayflies are a natural stamp of cleanliness in such places.
General Characteristics
Taxonomic Hierarchy
Kingdom:Animalia
Phylum:Arthropoda
Class:Insecta
Order:Ephemeroptera
Family:Baetidae, Ephemeridae, and others
Genus:Various
Species:spp.
Identifying Information
Scientific Name: Various spp.
Other Name(s): Dun; Spinner
Category:
Mayfly
Size (Adult; Length): 1mm to 30mm (0.04in to 1.17in)
Colors: yellow; brown; white; green; black
Descriptors: long wings; curved body; short life; flying; swarm; harmless; pollution indicator; naiad; imago; subimago; water
Note: An insect's reach is not limited by lines drawn on a map and therefore species may appear in areas, regions and/or states beyond those listed above as they are driven by environmental factors (such as climate change), available food supplies and mating patterns. Grayed-out selections indicate that the subject in question has not been reported in that particular territory. U.S. states and Canadian provinces / territories are clickable to their respective bug listings.
Colors: yellow; brown; white; green; black
