Ephemeroptera
Guides
Ironodes
Ironodes is a genus of mayflies in the family Heptageniidae, first described by Traver in 1935. Members of this genus are part of the diverse Heptageniidae family, commonly known as flat-headed mayflies due to their distinctive head morphology. The genus is represented by relatively few observations, suggesting it may be uncommon, geographically restricted, or underreported in surveys.
Ironodes nitidus
Ironodes nitidus is a species of flat-headed mayfly in the family Heptageniidae. The species was described by Eaton in 1885. It belongs to a genus of mayflies found in North America, with records from the Nearctic region including Middle America and North America. The genus Ironodes is part of the diverse Heptageniidae family, which contains many species adapted to running water habitats.
Isonychia arida
arid howdy mayfly
Isonychia arida is a species of brushlegged mayfly in the family Isonychiidae. It was described by Thomas Say in 1839, originally as Baetis arida. The species is found in North America and is known by the common name "arid howdy mayfly." Like other members of the genus Isonychia, it belongs to a group commonly referred to as "slate drakes" by anglers.
Isonychia bicolor
mahogany dun
Isonychia bicolor, commonly known as the mahogany dun, is a species of brushlegged mayfly in the family Isonychiidae. It is found in southeastern Canada and the eastern United States. Like all mayflies, it undergoes incomplete metamorphosis with aquatic nymphal stages and short-lived winged adults. The species is part of the EPT (Ephemeroptera-Plecoptera-Trichoptera) biological index used to assess water quality.
Isonychia campestris
Isonychia campestris is a filter-feeding mayfly species described by McDunnough in 1931. The immature nymphs inhabit lotic aquatic systems where they employ specialized morphological structures to capture suspended particulate matter from the water column. This species has been studied specifically for its filter feeding mechanisms, which involve interception and diffusive deposition of particles smaller than the pore spaces between filtering structures. The species occurs in the Nearctic region of North America.
Isonychia georgiae
Isonychia georgiae is a brushlegged mayfly species in the family Isonychiidae, first described by McDunnough in 1931. It is part of the order Ephemeroptera, an ancient lineage of aquatic insects dating to the Carboniferous period. Like other Isonychia species, it is known to anglers as a "slate drake" mayfly. The species is documented from North America.
Isonychia intermedia
Isonychia intermedia is a species of mayfly in the family Isonychiidae. Like other members of its genus, it is an aquatic insect with a life cycle consisting of an extended nymphal stage in freshwater habitats followed by a brief adult stage. The species is found in North America and is part of the EPT (Ephemeroptera-Plecoptera-Trichoptera) assemblage used in water quality biomonitoring. Adults are known to anglers as 'slate drakes' due to their dark wing coloration.
Isonychia rufa
Isonychia rufa is a brushlegged mayfly species in the family Isonychiidae, first described by McDunnough in 1931. It belongs to the bicolor group within its genus. The species is found in larger rivers and streams of the Mississippi drainage system in central North America.
Isonychia sicca
Brushlegged mayfly
Isonychia sicca is a brushlegged mayfly species in the family Isonychiidae, distributed across Central America and North America including southeastern Canada and Mexico. As a member of the order Ephemeroptera, it exhibits the characteristic aquatic nymphal stage and brief adult lifespan typical of mayflies. A life history study has documented this species in intermittent stream habitats in north central Texas, indicating adaptation to temporary aquatic environments.
Isonychia tusculanensis
Isonychia tusculanensis is a species of brushlegged mayfly in the family Isonychiidae, described by Berner in 1948. It belongs to a genus commonly referred to as "slate drake" mayflies. Like other members of the order Ephemeroptera, it has an aquatic nymphal stage and a short-lived adult stage. The species is documented from North America.
Iswaeon anoka
small minnow mayfly
Iswaeon anoka is a species of small minnow mayfly in the family Baetidae, first described by Daggy in 1945. The species is currently recognized under the genus Iswaeon, though it has been treated as a synonym of Heterocloeon anoka in some taxonomic databases. Like other members of Baetidae, it belongs to the diverse group of small mayflies commonly found in freshwater habitats.
Leptohyphes
little stout crawler mayflies
Leptohyphes is a genus of small, robust mayflies in the family Leptohyphidae, commonly referred to as "little stout crawler mayflies." The genus contains approximately 18 described species distributed primarily in the Neotropics, with a concentration in South America. Species in this genus are characterized by their crawling behavior and compact body form. The genus was established by Eaton in 1882.
Leptophlebia cupida
Early Brown Spinner, Black Quill
Leptophlebia cupida is a pronggilled mayfly species native to North America, commonly known as the early brown spinner or black quill. The species exhibits a univoltine life cycle with egg diapause during summer months. Nymphs develop through approximately 20-34 instars over 10 months, with emergence occurring from late April to mid-May. Adults are short-lived, non-feeding, and mate in swarms near streams.
Leptophlebia intermedia
Leptophlebia intermedia is a species of pronggilled mayfly in the family Leptophlebiidae. It was described by Traver in 1932. The species is found in North America.
Leptophlebia nebulosa
prong-gilled mayfly
Leptophlebia nebulosa is a species of prong-gilled mayfly in the family Leptophlebiidae. It is found in North America. The species belongs to a group characterized by their forked or prong-like gills, a distinctive morphological feature of the family Leptophlebiidae.
Leptophlebia pacifica
Leptophlebia pacifica is a species of pronggilled mayfly in the family Leptophlebiidae. It was described by McDunnough in 1933. The species occurs in North America within the Nearctic realm. As a member of Leptophlebiidae, it possesses the forked gills characteristic of this family.
Leucrocuta aphrodite
Leucrocuta aphrodite is a species of flatheaded mayfly in the family Heptageniidae. It inhabits freshwater streams and rivers in eastern North America. The species was described by McDunnough in 1926.
Leucrocuta hebe
flatheaded mayfly
Leucrocuta hebe is a species of flatheaded mayfly in the family Heptageniidae. This species is found across parts of North America, including the northern and southeastern United States and northern Canada. As a member of the order Ephemeroptera, it has an aquatic larval stage and a short-lived adult stage.
Leucrocuta jewetti
Jewett's Flat-headed Mayfly
Leucrocuta jewetti is a species of flatheaded mayfly in the family Heptageniidae. It is known from southeastern Canada and the northwestern United States. As a member of the Heptageniidae, it belongs to a family of mayflies commonly associated with running water habitats. The species was described by Allen in 1966.
Leucrocuta juno
Leucrocuta juno is a species of flatheaded mayfly in the family Heptageniidae, described by McDunnough in 1924. It belongs to the order Ephemeroptera, a group of aquatic insects known for their brief adult lifespan. The species is native to North America and is part of a genus characterized by distinctive morphological features typical of heptageniid mayflies.
Leucrocuta minerva
Leucrocuta minerva is a species of mayfly in the family Heptageniidae, described by McDunnough in 1924. It belongs to a genus of small to medium-sized flat-headed mayflies commonly known as "little yellow quills" or similar vernacular names. Species in this genus are typically associated with running water habitats. The specific epithet "minerva" refers to the Roman goddess of wisdom, though the etymological reasoning behind this choice is not documented in available sources.
Leucrocuta thetis
Leucrocuta thetis is a species of flatheaded mayfly in the family Heptageniidae. It is known from North America. As a member of the Heptageniidae, it belongs to a group of mayflies commonly associated with running water habitats. The species was described by Traver in 1935.
Maccaffertium
flatheaded mayflies
Maccaffertium is a genus of mayflies in the family Heptageniidae, commonly known as flatheaded mayflies. The genus was established by Bednarik in 1979 and contains approximately 19–20 described species. Like other members of Heptageniidae, these mayflies are characterized by their flattened, streamlined bodies adapted for life in flowing water. The genus is found in North America, with species distributed across various freshwater habitats.
Maccaffertium mediopunctatum
flat-headed mayfly
Maccaffertium mediopunctatum is a species of flat-headed mayfly in the family Heptageniidae. It occurs in Southeastern Canada and the Eastern United States. The species has two recognized subspecies: M. m. arwini and M. m. mediopunctatum. Like other members of its genus, it exhibits the unique mayfly developmental trait of having a fully winged subadult stage (subimago) that requires one additional molt to reach sexual maturity.
Maccaffertium mediopunctatum arwini
A subspecies of mayfly in the family Heptageniidae. Like other members of its genus, it exhibits the characteristic subimago stage—fully winged but sexually immature—unique among insects. Adults are short-lived, emerging from aquatic habitats to mate. The subspecific epithet honors an individual, following the pattern of other Maccaffertium subspecies.
Maccaffertium mediopunctatum mediopunctatum
Maccaffertium mediopunctatum mediopunctatum is a subspecies of mayfly in the family Heptageniidae. The genus Maccaffertium was established to accommodate species formerly placed in Heptagenia and related genera, distinguished by particular features of the male genitalia and wing venation. This subspecies is part of a group of flatheaded mayflies commonly found in North American streams and rivers. Subimagos (subadults) of this species exhibit the characteristic pale, milky-white coloration and opaque wings typical of the genus, with sexual dimorphism in eye size and abdominal claspers.
Maccaffertium meririvulanum
fresh flat-headed mayfly
Maccaffertium meririvulanum is a species of flatheaded mayfly in the family Heptageniidae, characterized by its distinctive flattened head morphology typical of this group. The species is known from North America, where it inhabits freshwater lotic environments. As with other members of the genus, it undergoes the unique mayfly developmental pattern involving a winged subadult (subimago) stage that molts once more to reach sexual maturity.
Maccaffertium mexicanum
flatheaded mayfly
A flatheaded mayfly species in the family Heptageniidae. Adults are attracted to light sources near aquatic habitats. The species possesses the unique mayfly trait of developing fully functional wings during the subimago (sub-adult) stage, requiring one additional molt to reach sexual maturity. Two subspecies are recognized: M. m. integrum and M. m. mexicanum.
Maccaffertium modestum
flatheaded mayfly
Maccaffertium modestum is a species of flatheaded mayfly in the family Heptageniidae. It occurs in North America, specifically in the eastern United States and southeastern Canada. The species exhibits the characteristic subimago stage typical of mayflies, where fully functional wings develop before the final molt to adulthood.
Maccaffertium pudicum
flatheaded mayfly
Maccaffertium pudicum is a species of flatheaded mayfly in the family Heptageniidae. It is found in North America. The species exhibits the characteristic subimago stage typical of mayflies, where fully functional wings develop before the final molt to adulthood.
Maccaffertium terminatum placitum
Maccaffertium terminatum placitum is a subspecies of mayfly in the family Heptageniidae. Like other members of the genus, it exhibits the unique mayfly developmental trait of having a functional winged sub-adult stage (subimago) prior to the final molt to sexual maturity. The subimago is characterized by milky-white, opaque wings and paler body coloration compared to the transparent-winged adult. This subspecies is part of the Nearctic fauna of North America.
Matriella
Matriella is a genus of mayflies in the family Ephemerellidae, established by Jacobus & McCafferty in 2008. As a relatively recently described genus within the spiny crawler mayfly family, it represents part of the ongoing taxonomic refinement of Ephemerellidae. The genus belongs to the order Ephemeroptera, an ancient group of aquatic insects with aquatic immature stages and terrestrial adults. Specific details about species diversity and biology within Matriella remain limited in available sources.
Matriella teresa
Matriella teresa is a species of spiny crawler mayfly in the family Ephemerellidae, described by Traver in 1934. It belongs to a genus of mayflies found in North America. As with other members of Ephemerellidae, it likely inhabits freshwater streams and rivers during its aquatic nymphal stage.
Metretopodidae
cleftfooted minnow mayflies
Metretopodidae is a family of mayflies in the order Ephemeroptera, commonly known as cleftfooted minnow mayflies. The family contains at least 3 genera (Metreplecton, Metretopus, Siphloplecton) and more than 20 described species. These mayflies are part of the diverse aquatic insect fauna associated with freshwater habitats.
Metretopus
Metretopus is a genus of mayflies (Ephemeroptera) in the family Metretopodidae, containing at least two species: M. alter and M. borealis. These insects are found across northern regions of Europe, Russia, and North America. The genus has historically posed identification challenges, with M. alter frequently misidentified as M. borealis until morphological distinguishing characters were established.
Metretopus borealis
Metretopus borealis is a mayfly species in the family Metretopodidae, originally described as Heptagenia borealis by Eaton in 1871. It is distributed across the Nearctic and Palearctic regions, with confirmed presence in North America. The species belongs to a small family of mayflies whose members are typically associated with cool, flowing waters.
Neocloeon
Neocloeon is a genus of mayflies in the family Baetidae. The species Neocloeon triangulifer has emerged as an important laboratory model organism for aquatic ecotoxicology and physiological studies due to its sensitivity to environmental stressors and ability to complete its life cycle in controlled conditions. The genus is distinguished by parthenogenetic reproduction in at least some populations, a trait that facilitates laboratory culture. Species in this genus inhabit freshwater streams and serve as bioindicators for water quality assessment.
Neoephemera
large squaregill mayflies
Neoephemera is a genus of large squaregill mayflies in the family Neoephemeridae, established by McDunnough in 1925. The genus contains approximately six extant species distributed across North America and Asia, plus one extinct species from the Eocene of Washington State. Species range from moderate to large size within the family, with body lengths varying considerably. The genus has been subject to taxonomic revision, with at least one species (N. projecta) transferred to a new genus Pulchephemera based on phylogenetic analysis of plesiomorphic characters.
Neoephemera purpurea
large squaregill mayfly
Neoephemera purpurea is a species of large squaregill mayfly in the family Neoephemeridae. It was originally described as Oreianthus purpureus by Traver in 1931. The species is known from North America, though specific details about its biology and ecology remain poorly documented.
Neoephemera youngi
Neoephemera youngi is a species of mayfly in the family Neoephemeridae, described by Berner in 1953. It belongs to a small family of mayflies with limited distribution records in the Nearctic region. Very little specific information about this species' biology, ecology, or appearance has been documented in accessible literature.
Neoephemeridae
large squaregill mayflies
Neoephemeridae is a small family of mayflies in the suborder Furcatergalia, containing approximately 13-17 described species across four genera: Neoephemera (Nearctic), Ochernova (Central Asia), Leucorhoenanthus (West Palearctic), and Potamanthellus (East Palearctic and Oriental). Nymphs are characterized by distinctive fimbriate (fringed) dorsal-oriented gills on abdominal segments, giving rise to the common name "large squaregill mayflies." The family has a disjunct Holarctic-Oriental distribution with recent findings in southwestern and northwestern China linking previously isolated genera biogeographically.
Neoleptophlebia assimilis
Southeastern Prong-gilled Mayfly
Neoleptophlebia assimilis is a species of prong-gilled mayfly in the family Leptophlebiidae. It is known from the southeastern United States. The species belongs to a genus characterized by gills with divided, finger-like lobes. Mayflies in this family are typically associated with running water habitats and serve as important indicators of water quality.
Neoleptophlebia mollis
soft prong-gilled mayfly
Neoleptophlebia mollis is a species of prong-gilled mayfly in the family Leptophlebiidae. The species was first described by Eaton in 1871. It belongs to a genus characterized by forked gills on abdominal segments, a trait reflected in the common name "prong-gilled mayfly." The specific epithet "mollis" (Latin for "soft") likely refers to some aspect of the species' morphology or texture.
Nixe
Nixe is a genus of mayflies in the family Heptageniidae, established by Flowers in 1980. These aquatic insects belong to the order Ephemeroptera, characterized by their short adult lifespan and complex life cycles involving aquatic nymphal stages. The genus has been documented in 451 iNaturalist observations, indicating moderate levels of citizen science engagement. As heptageniid mayflies, members of this genus likely inhabit flowing water environments where their nymphs develop.
Nixe inconspicua
Nixe inconspicua is a species of flatheaded mayfly in the family Heptageniidae, first described by McDunnough in 1924. As a member of the Heptageniidae, it possesses the characteristic dorsoventrally flattened body form typical of this family. The species is known from North America, though specific details about its biology and ecology remain limited in the available literature.
Nixe lucidipennis
clear-winged flat-headed mayfly
Nixe lucidipennis is a species of flat-headed mayfly in the family Heptageniidae, distributed across North America. The species was described by Clemens in 1913. It is known from a limited number of observations, with records indicating presence in the Nearctic region. As a member of the genus Nixe, it belongs to a group of mayflies characterized by their flattened head morphology and association with running water habitats.
Oligoneuriidae
Brushlegged Mayflies, Brushleg Mayflies
Oligoneuriidae is a family of mayflies characterized by specialized filtering structures on their nymphs' forelegs, earning them the common name "brushlegged mayflies." The family exhibits a pantropical distribution with at least 68 described species across over a dozen genera, including both extant and extinct lineages from the Cretaceous period. Nymphs possess two rows of setae on the forelegs used for filter feeding and tufts of gills at the base of their maxillae. The family has been documented from freshwater habitats across Africa, South America, the Mediterranean region, and the Middle East, with some species showing extended multiyear life cycles.
Palingeniidae
spiny-headed burrowing mayflies
Palingeniidae is a family of large mayflies commonly known as spiny-headed burrowing mayflies. Adults are characterized by having more than four longitudinal cross-veins on their wings, with males possessing short, wide pronota and well-developed legs in both sexes. Female cerci are shorter than the body. Nymphs are burrowers in muddy substrates of large rivers. The family includes notable species such as Palingenia longicauda, the largest European mayfly at up to 12 cm in length.
Paracloeodes
Paracloeodes is a genus of small minnow mayflies in the family Baetidae, established by Day in 1955. The genus contains at least 23 described species distributed across the Americas, with the highest diversity concentrated in the Neotropical region. Nymph-adult associations have been established for only nine species, indicating significant gaps in life stage knowledge. Recent taxonomic work has focused on describing new species and clarifying previously unknown adult stages, such as for P. carolinae.
Paracloeodes minutus
small minnow mayfly
Paracloeodes minutus is a small minnow mayfly in the family Baetidae. It is found in Central America and North America, including southeastern Canada, northern Mexico, and the continental United States. The species was described by Daggy in 1945.