Mayfly
Guides
Cinygma integrum
Cinygma integrum is a North American mayfly species in the family Heptageniidae. It is one of three Cinygma species on the continent. The life history has been studied in Oregon, where nymphs occupy submerged wood habitats year-round and adults emerge from mid-May to mid-July. The nymph is the only described member of its genus in North America.
Cinygma lyriforme
Cinygma lyriforme is a species of flatheaded mayfly in the family Heptageniidae, originally described as Ecdyonurus lyriformis by James Halliday McDunnough in 1924. The species name "lyriforme" refers to the lyre-shaped pattern characteristic of this taxon. Like other members of Heptageniidae, it possesses dorsoventrally flattened nymphs adapted for clinging to substrates in flowing water. The genus Cinygma is a small Nearctic genus with limited species diversity.
Cinygmula reticulata
Cinygmula reticulata is a species of mayfly in the family Heptageniidae, first described by McDunnough in 1934. It is a member of the Nearctic fauna, occurring in North America. Like other members of the genus Cinygmula, it is associated with running water habitats where the aquatic nymphs develop. The species is represented by limited observation records, with only four observations documented on iNaturalist.
Cinygmula subaequalis
flatheaded mayfly
Cinygmula subaequalis is a flatheaded mayfly species in the family Heptageniidae. It is distributed across northern North America, including Alaska, northern Canada, and the eastern United States. The species belongs to a genus characterized by distinctive head morphology. Limited observational data suggests it is rarely encountered.
Diphetor
Diphetor is a genus of small mayflies in the family Baetidae, established by Waltz and McCafferty in 1987. These insects belong to the order Ephemeroptera, characterized by their short adult lifespan and aquatic nymphal stages. The genus is part of the diverse Baetidae family, one of the largest families of mayflies.
Diphetor hageni
Hagen's Small Minnow Mayfly
Diphetor hageni is a small mayfly species in the family Baetidae, commonly known as Hagen's Small Minnow Mayfly. It is native to the Nearctic region, primarily distributed across North America. The species is part of the diverse Baetidae family, which are among the most abundant and widespread mayflies in running waters.
Dolania americana
American Sand-burrowing Mayfly
Dolania americana is a predacious, sand-burrowing mayfly and the sole species in the genus Dolania. Adults exhibit an exceptionally brief lifespan, emerging before dawn, mating, and dying within approximately thirty minutes. Females deposit eggs in water and die within five minutes of emergence, representing the shortest known adult lifespan among mayflies. The species has a two-year life cycle with synchronous mass emergence and specialized reproductive adaptations including large, energy-rich eggs that produce unusually large first-instar larvae.
Drunella coloradensis
Small Western Green Drake
Drunella coloradensis is a species of spiny crawler mayfly in the family Ephemerellidae, commonly known to anglers as the Small Western Green Drake. The species is found in freshwater streams across western North America, with a range extending from Alaska and northern Canada through the western United States to northern Mexico and Central America. Nymphs are known to alter their behavior in response to short-term pH reductions, becoming more active under acidic conditions. The species is of particular importance to fly fishermen, who imitate its various life stages with artificial flies.
Drunella cornutella
spiny crawler mayfly
Drunella cornutella is a species of spiny crawler mayfly in the family Ephemerellidae, originally described by McDunnough in 1931 as Ephemerella cornutella. It is found in North America, with records from the Nearctic region including the northeastern United States. Like other members of the genus Drunella, it is an aquatic insect with immature stages living in freshwater habitats.
Drunella doddsii
Western Green Drake
Drunella doddsii is a species of spiny crawler mayfly in the family Ephemerellidae, commonly known as the Western Green Drake. Originally described as Ephemerella doddsi by Needham in 1927, this species is significant to fly fishing communities in western North America. The species is part of the diverse Drunella genus, which includes other notable green drake species such as D. grandis.
Drunella flavilinea
Flav
Drunella flavilinea is a species of spiny crawler mayfly in the family Ephemerellidae. It is native to Central America and North America, with a range spanning southwestern Canada, the western United States, and northern Mexico. The species is known to fly fishermen by the common name "Flav" and is an important component of trout diets in western streams.
Drunella grandis
Western Green Drake, Green Drake, Spinner Green Drake
Drunella grandis is a species of spiny crawler mayfly in the family Ephemerellidae. It is commonly known as the Western Green Drake among fly fishermen, who highly value this species for its importance as a trout food source. The species is native to North America and has been documented with three recognized subspecies. Adults are notable for their large size and greenish coloration, making them a prominent feature of western North American streams.
Drunella lata
Drunella lata is a species of spiny crawler mayfly in the family Ephemerellidae. It was first described by Morgan in 1911. The species is found in North America and belongs to a genus commonly known as "green drakes" among fly fishermen. Like other members of Ephemerellidae, it has aquatic nymphs and winged adults.
Drunella pelosa
Drunella pelosa is a species of spiny crawler mayfly in the family Ephemerellidae. It is native to North America. As a member of the Ephemerellidae family, it shares characteristics with other spiny crawler mayflies, including a robust body form and adaptations for clinging to substrates in flowing water. The species was originally described as Ephemerella pelosa by Mayo in 1952.
Drunella spinifera
Western Slate Olive
Drunella spinifera is a species of spiny crawler mayfly in the family Ephemerellidae. It is found in southwestern and northern Canada, the western United States, and Alaska. The common name "Western Slate Olive" reflects its regional distribution and likely coloration. Like other members of the genus Drunella, it belongs to a group of mayflies commonly targeted by fly fishermen, though specific angling references for this species are limited.
Drunella walkeri
Small Blue-winged Olive
Drunella walkeri is a species of spiny crawler mayfly in the family Ephemerellidae, commonly known as the Small Blue-winged Olive among anglers. It is found in North America and is one of the mayfly species frequently imitated by fly fishermen. The species was first described by Eaton in 1884.
Epeorus
Epeorus is a genus of mayflies in the family Heptageniidae. The genus contains multiple subgenera including Caucasiron and Siniron, with species distributed across the Palearctic and Nearctic regions. Larvae are primarily lotic, inhabiting running waters where many species serve as bioindicators for water quality assessments. Several species are dominant components of macroinvertebrate assemblages in upper and midstream river areas.
Epeorus albertae
flatheaded mayfly
Epeorus albertae is a flatheaded mayfly in the family Heptageniidae, distributed across northern and western North America. Laboratory studies indicate that nymphal growth rate and activity are strongly temperature-dependent, with optimal growth occurring at 15°C compared to slower development at lower temperatures. Nymphs exhibit behavioral thermoregulation by seeking refugia at cold temperatures, suggesting adaptation to thermally variable stream environments.
Epeorus deceptivus
flatheaded mayfly
Epeorus deceptivus is a species of flatheaded mayfly in the family Heptageniidae. First described by McDunnough in 1924, it was originally placed in the genus Cinygma before being transferred to Epeorus. It is found in North America.
Epeorus fragilis
flatheaded mayfly
Epeorus fragilis is a species of flatheaded mayfly in the family Heptageniidae, first described by Morgan in 1911. It is distributed across North America. As a member of the order Ephemeroptera, it undergoes aquatic larval development before emerging as a short-lived adult.
Epeorus longimanus
flatheaded mayfly
Epeorus longimanus is a flatheaded mayfly species in the family Heptageniidae. Nymphs inhabit stream riffles and show specific microhabitat preferences, being more abundant in areas with smaller sediment sizes, higher live periphyton biomass, and lower densities of invertebrate predators. The species is distributed across western North America from Alaska through the western United States to southwestern and northern Canada.
Epeorus pleuralis
Quill Gordon
Epeorus pleuralis, commonly known as the Quill Gordon, is a flatheaded mayfly in the family Heptageniidae. It is native to North America and is recognized as an important species in aquatic entomology and fly fishing. The species is known for its relatively early emergence in the spring, making it a significant hatch for anglers in eastern North American streams.
Epeorus punctatus
Epeorus punctatus is a species of flat-headed mayfly in the family Heptageniidae. The species was originally described by McDunnough in 1925 under the genus Iron before being transferred to Epeorus. It is known from North America within the Nearctic region. Like other members of the genus, it likely inhabits flowing water environments where the nymphs cling to submerged substrates.
Ephemera blanda
common burrower mayfly
Ephemera blanda is a species of burrower mayfly in the family Ephemeridae, characterized by its fossorial lifestyle in aquatic sediments. The species inhabits running waters in the southeastern Nearctic region. As with other members of the genus Ephemera, adults are short-lived and primarily focused on reproduction.
Ephemera guttulata
Eastern Green Drake, Shad Fly, Coffinfly
Ephemera guttulata, commonly known as the eastern green drake, is a burrowing mayfly species native to eastern North America. It is one of the largest mayfly species in the region and is highly significant to fly fishing, where its emergence events are eagerly anticipated. The species has a fully aquatic larval stage, followed by a winged subimago (dun) stage and a short-lived sexually mature adult (imago) stage. Its conservation status is G5 (secure) according to NatureServe.
Ephemera simulans
Brown Drake
Ephemera simulans is a burrowing mayfly species in the family Ephemeridae, commonly known as the Brown Drake. It is widely distributed across North America, particularly common in the Rocky Mountains, Midwest, and Great Lakes region. The species is economically significant in recreational fly fishing, where both nymph and adult stages are imitated with artificial flies. Nymphs inhabit sand and silt substrates of lakes and streams, emerging as adults primarily at night from mid-June to mid-July.
Ephemera varia
Yellow Drake
Ephemera varia, commonly known as the Yellow Drake, is a species of burrower mayfly in the family Ephemeridae. It is native to North America, with documented presence in the northeastern United States including Vermont. Like other members of its genus, it is associated with aquatic environments and has a brief adult lifespan. The species is represented by 59 observations on iNaturalist, indicating it is documented but not extensively studied.
Ephemerella
Hendricksons, Sulphurs, Pale Duns
Ephemerella is a genus of spiny crawler mayflies comprising approximately 19 described species. Nymphs are characterized by their distinctive defensive posture, curling the abdomen upward in a scorpion-like manner when disturbed. The genus has a widespread distribution across North America and Europe, with species occupying diverse lotic freshwater habitats. Several species, including E. subvaria and E. ignita, have been subjects of detailed life history studies.
Ephemerella aurivillii
spiny crawler mayfly
Ephemerella aurivillii is a spiny crawler mayfly in the family Ephemerellidae with a strict one-year life cycle. The species occurs across northern regions of the Northern Hemisphere, including Europe, northern Asia, and North America. Research in Norway demonstrated that its distribution and growth rates are strongly temperature-dependent, with populations expanding following hydropower-induced warming of previously cold streams.
Ephemerella dorothea
Pale Dun
Ephemerella dorothea is a species of spiny crawler mayfly in the family Ephemerellidae, commonly known as the Pale Dun. It is native to North America, with documented occurrence in southwestern and northern Canada, the western United States, and Alaska. The species was first described by Needham in 1908 and includes two recognized subspecies: E. d. dorothea and E. d. infrequens.
Ephemerella dorothea infrequens
Pale Morning Dun
Ephemerella dorothea infrequens is a subspecies of mayfly in the family Ephemerellidae, commonly known as the Pale Morning Dun. It is an aquatic insect whose nymphal stage inhabits freshwater environments. The species is recognized as an important food source for trout and is frequently imitated by fly fishers using artificial flies. It was described by McDunnough in 1924 and is accepted as a valid subspecies within the Ephemerella dorothea complex.
Ephemerella excrucians
Pale Morning Dun
Ephemerella excrucians, commonly known as the pale morning dun, is a species of spiny crawler mayfly in the family Ephemerellidae. It is distributed across all of Canada and the continental United States. The species is of particular interest to fly fishers due to its importance as a trout food source and its frequent use as a model for artificial flies.
Ephemerella invaria
Sulphur Dun
Ephemerella invaria, commonly known as the sulphur dun, is a species of spiny crawler mayfly in the family Ephemerellidae. It occurs in headwater streams across eastern North America, from southeastern and northern Canada through the eastern United States. The species has been studied for population genetic impacts associated with deforestation of its stream habitats. As a member of the Ephemerellidae, it belongs to a group of mayflies characterized by distinctive spiny or tuberculate body features.
Ephemerella maculata
spiny crawler mayfly
Ephemerella maculata is a species of spiny crawler mayfly in the family Ephemerellidae. It exhibits a migratory life cycle involving upstream flight of adults, downstream drift of nymphs, and upstream crawling by nymphs to compensate for displacement. The species is found in North American streams.
Ephemerella subvaria
red quill, Dark Hendrickson
Ephemerella subvaria is a spiny crawler mayfly in the family Ephemerellidae. The species was described by McDunnough in 1931. It is widely distributed in the eastern United States with limited occurrence in the upper Midwest. A 2019 record from Ohio represents the first state documentation, with specimens reared from nymphs collected in March to adult emergence in late April.
Ephemerella verruca
Ephemerella verruca is a species of mayfly in the family Ephemerellidae, described by Allen and Edmunds in 1965. It belongs to the order Ephemeroptera, a group of aquatic insects commonly known as mayflies. The species is recorded from the Nearctic region, specifically North America. Like other members of its genus, it has an aquatic larval stage and terrestrial adult stage.
Ephemerellidae
Spiny Crawler Mayflies
Ephemerellidae, commonly known as spiny crawler mayflies, is a family of mayflies (Ephemeroptera) comprising approximately 90 species across 8-14 genera. The family is distributed throughout North America and the UK, with additional records from Europe and Asia. Nymphs inhabit lotic-erosional environments including flowing streams of all sizes, lake shores, and beaches with wave action. They are primarily collector-gatherers and serve as important indicators of water quality due to their sensitivity to pollution.
Eurylophella aestiva
spiny crawler mayfly
Eurylophella aestiva is a species of spiny crawler mayfly in the family Ephemerellidae. It was originally described by McDunnough in 1931 as Ephemerella aestiva. The species is known from North America and belongs to a genus characterized by distinctive spiny projections on the body. Like other members of Ephemerellidae, it exhibits the subimago stage typical of mayflies.
Eurylophella bicolor
bicolor spiny crawler mayfly
Eurylophella bicolor is a species of spiny crawler mayfly in the family Ephemerellidae, originally described as Ephemerella bicolor by Clemens in 1913. The species is distributed across the Nearctic region, particularly in North America. Like other members of the genus Eurylophella, it is associated with freshwater aquatic habitats during its nymphal stages.
Eurylophella funeralis
Eurylophella funeralis is a mayfly species in the family Ephemerellidae, described by McDunnough in 1925. Originally placed in the genus Ephemerella, it was later transferred to Eurylophella. The species is known from the Nearctic region, with records from North America including Vermont. As a member of the order Ephemeroptera, it has an aquatic larval stage and terrestrial adult stage, though specific ecological details for this species remain limited in available literature.
Eurylophella lodi
Eurylophella lodi is a species of spiny crawler mayfly in the family Ephemerellidae, described by Mayo in 1952. It belongs to a genus of mayflies found in North America. The species is known from limited observations, with only two documented occurrences in iNaturalist. Like other members of Ephemerellidae, it is likely associated with freshwater aquatic habitats during its immature stages.
Eurylophella prudentalis
spiny crawler mayfly
Eurylophella prudentalis is a species of spiny crawler mayfly in the family Ephemerellidae, first described by James Halliday McDunnough in 1931. As a member of the genus Eurylophella, it belongs to a group of mayflies commonly known as spiny crawlers, characterized by their distinctive body armature. The species is known from North America, with documented occurrences in the northeastern United States including Vermont. Like other Ephemerellidae, it completes its aquatic larval development in freshwater habitats before emerging as a short-lived adult.
Fallceon quilleri
Fallceon quilleri is a small minnow mayfly in the family Baetidae, described by Dodds in 1923. It is known from a relatively small number of observations (15 records on iNaturalist). The species has a broad transcontinental distribution spanning temperate and tropical regions of the Americas.
Habrophlebia vibrans
pronggilled mayfly
A small stream-dwelling mayfly with a 2-year life cycle, notable for its extended development compared to most mayflies. Adults emerge synchronously in June. Nymphs inhabit gravel substrates and show distinct drift patterns across life stages. The species has been studied in Québec populations, where it reaches final sizes of approximately 5 mm before emergence.
Heptagenia marginalis
Margined Flat-headed Mayfly
Heptagenia marginalis is a species of flatheaded mayfly in the family Heptageniidae, first described by Banks in 1910. It belongs to a family characterized by dorsoventrally flattened body forms adapted to clinging in fast-flowing water. The species is known from North America, though detailed biological information remains limited in available literature.
Heptagenia pulla
dusky flat-headed mayfly
Heptagenia pulla is a species of flat-headed mayfly in the family Heptageniidae, commonly known as the dusky flat-headed mayfly. The species was described by Clemens in 1913 and is native to the Nearctic region. Like other members of its genus, it is associated with flowing freshwater habitats. The specific epithet "pulla" refers to the dusky or dark coloration characteristic of this species.
Heptagenia solitaria
solitary flat-headed mayfly
Heptagenia solitaria is a species of flatheaded mayfly in the family Heptageniidae, first described by McDunnough in 1924. The species is distributed across southwestern and northern Canada and the western United States. As a member of the Heptageniidae, it belongs to a family of mayflies commonly known as flatheaded mayflies due to their distinctive head morphology.
Heterocloeon curiosum
curious small minnow mayfly
Heterocloeon curiosum is a small minnow mayfly in the family Baetidae, native to North America. It has been studied in Virginia river systems, where it demonstrates bivoltine life history with two summer generations. Reservoir construction with surface release can significantly alter its emergence timing, larval density, and fecundity through thermal regime changes.
Heterocloeon petersi
small minnow mayfly
Heterocloeon petersi is a small minnow mayfly species in the family Baetidae, first described by Müller-Liebenau in 1974. It is recorded from the southeastern United States. As a member of Baetidae, it belongs to one of the most diverse families of mayflies, though specific biological details for this species remain limited in published literature.
Hexagenia
giant mayflies, burrowing mayflies, fishflies
Hexagenia is a genus of large burrowing mayflies in the family Ephemeridae, comprising eight recognized species. Nymphs construct distinctive U-shaped, ventilated burrows in soft aquatic sediments of lakes, streams, and ponds. Adults are notable for their synchronous mass emergences, which can produce swarms dense enough to appear on weather radar. The genus serves as an important bioindicator of water quality due to its intolerance of pollution and anoxia.