Aquatic-insect
Guides
Microcylloepus
Microcylloepus is a genus of riffle beetles (family Elmidae) established by Hinton in 1935. The genus contains approximately nine described species distributed primarily in the Americas, with records from the United States to Colombia. These beetles are aquatic and inhabit flowing water environments, particularly springs and spring-runs. One species, Microcylloepus pusillus, has been studied in detail at Comal Springs, Texas, where it coexists with the endangered beetle Heterelmis comalensis.
Microvelia americana
Broad-Shouldered Water Strider
Microvelia americana is a small water strider in the family Veliidae, commonly known as the Broad-Shouldered Water Strider. It inhabits aquatic environments across North America. As a member of the Gerromorpha, it is adapted to life on the water surface, using surface tension to move and forage.
Microvelia signata
Microvelia signata is a small water strider in the family Veliidae, found in aquatic and semi-aquatic habitats across North and Middle America. Like other members of the genus Microvelia, it is adapted for life on the water surface, using surface tension to skate across ponds, streams, and other freshwater bodies. The species was described by Philip Uhler in 1894 and is recognized as a valid taxon in current classifications.
Molanna blenda
hood casemaker
Molanna blenda is a species of caddisfly in the family Molannidae, commonly referred to as hood casemakers. The species was described by Sibley in 1926. It is known from North America, where it inhabits freshwater environments. Like other members of Molannidae, larvae construct distinctive portable cases using silk and sand particles.
Mosillus tibialis
shore fly
Mosillus tibialis is a species of shore fly in the family Ephydridae, first described by Cresson in 1916. The species is distributed across North America, including Canada, the United States, Mexico, and the Bahamas, with introduced populations in the Hawaiian Islands. Shore flies in this family are typically associated with aquatic or semi-aquatic habitats. The specific epithet "tibialis" refers to a characteristic of the tibiae (leg segments), though the precise diagnostic feature is not detailed in available sources.
Nebrioporus depressus
Nebrioporus depressus is a predaceous diving beetle (Coleoptera: Dytiscidae) first described by Fabricius in 1775. It belongs to the N. depressus-group, the most speciose species-group within the genus Nebrioporus. The species is distributed across the Holarctic region, occurring in Europe, Northern Asia (excluding China), and North America. As a member of Dytiscidae, it is adapted to aquatic habitats where it functions as an active predator.
Nectopsyche
White Miller Caddisflies, White Millers
Nectopsyche is a genus of caddisflies in the family Leptoceridae, commonly known as white millers. The genus contains at least 70 described species distributed across the Americas, with records from North America through the tropical Andes. Species occupy diverse freshwater habitats ranging from lentic (still-water) environments to lotic (flowing) highland streams. Several species have been studied as bioindicators of aquatic pollution due to their sensitivity to pesticides and heavy metals.
Nectopsyche albida
White Miller Caddisfly
Nectopsyche albida is a species of long-horned caddisfly in the family Leptoceridae. It is found in North America. The species is associated with lentic (still-water) habitats including lakes and ponds.
Nectopsyche candida
Radiant Long-horned Caddisfly
Nectopsyche candida is a species of long-horned caddisfly in the family Leptoceridae. It is found in North America. The species belongs to a genus characterized by elongated antennae, a trait reflected in the common name for this group. Like other caddisflies, it has an aquatic larval stage and terrestrial adult stage.
Nectopsyche exquisita
exquisite long-horned caddisfly
Nectopsyche exquisita is a species of long-horned caddisfly in the family Leptoceridae, characterized by its distinctive wing patterning and banded antennae. Adults are medium-sized caddisflies with striking yellow and white hair patterns on the wings. The species is found in eastern North America near slow-moving aquatic habitats. Adults are attracted to light and have been documented in urban settings.
Neochetina
water hyacinth weevil, waterhyacinth weevils
Neochetina is a genus of weevils native to South America, comprising at least two species: N. eichhorniae (mottled water hyacinth weevil) and N. bruchi (chevroned water hyacinth weevil). Both species are highly host-specific biological control agents used worldwide to manage invasive water hyacinth (Eichhornia crassipes). The genus has been introduced to over 30 countries including the United States, where releases began in Florida in 1972 (N. eichhorniae) and 1974 (N. bruchi).
Neochetina bruchi
chevroned water hyacinth weevil, chevroned waterhyacinth weevil
Neochetina bruchi is a South American marsh weevil introduced to over 30 countries as a biological control agent for invasive water hyacinth (Pontederia crassipes, formerly Eichhornia crassipes). First released in the United States in Florida in 1974, it now occurs throughout the Gulf Coast states and California. The species has been studied extensively for its effectiveness in managing water hyacinth infestations, with research showing its performance varies with environmental factors including salinity, temperature, and nutrient availability.
Neochetina eichhorniae
Mottled Waterhyacinth Weevil, Mottled Water Hyacinth Weevil
Neochetina eichhorniae is a host-specific weevil native to Argentina and neighboring South American regions. It was introduced to Florida in 1972 as a biological control agent for the invasive aquatic weed water hyacinth (Eichhornia crassipes) and has since been established in more than three dozen countries worldwide. Adults feed on leaves and petioles, producing characteristic feeding scars, while larvae tunnel into petioles and the plant crown. The species has demonstrated substantial suppression of water hyacinth growth, reducing biomass, flower production, and water surface coverage.
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.
Neoclypeodytes amybethae
Neoclypeodytes amybethae is a species of predaceous diving beetle in the family Dytiscidae, described by K. B. Miller in 2001 as part of a comprehensive revision of the New World genus Neoclypeodytes. The genus contains 25 valid species distributed in western North America and northern Central America. Species in this genus are characterized by a distinctive pattern of two maculae on each elytron, which represents a possible synapomorphy supporting the monophyly of Neoclypeodytes.
Neoclypeodytes cinctellus
Neoclypeodytes cinctellus is a small predaceous diving beetle in the family Dytiscidae. It is distributed across western North America and northern Central America. The species has been documented as a predator of the critically endangered Devils Hole pupfish (*Cyprinodon diabolis*), representing a notable conservation concern. It was formerly described under the name *N. centralis* before being synonymized.
Neohermes angusticollis
narrow-collared fishfly
Neohermes angusticollis is a fishfly species in the family Corydalidae, order Megaloptera. It occurs in North America. As with other fishflies, adults are typically nocturnal and are attracted to lights. The genus Neohermes is distinguished from related genera by features of the male genitalia and wing venation.
Neohermes californicus
California fishfly
Neohermes californicus is a species of fishfly in the family Corydalidae, first described by Walker in 1853 as Chauliodes californicus. It belongs to the order Megaloptera, a small group of primitive holometabolous insects that includes fishflies, dobsonflies, and alderflies. The species is found in North America, particularly in western regions including California. Fishflies in this genus are associated with aquatic habitats during their larval stages. Adults are typically nocturnal and attracted to lights.
Neohermes concolor
fishfly
Neohermes concolor is a species of fishfly in the family Corydalidae, order Megaloptera. It is found in North America, with distribution records from the United States including Vermont. The species was originally described by K. Davis in 1903 under the basionym Chauliodes concolor before being transferred to the genus Neohermes. Fishflies in this family are characterized by their elongated bodies, large membranous wings, and aquatic larval stages.
Neohermes filicornis
Fishfly
Neohermes filicornis is a long-lived aquatic fishfly (Megaloptera: Corydalidae) inhabiting intermittent streams across North America. The species exhibits burrowing behavior and is adapted to temporary water systems with periodic drying. Adults are terrestrial while larvae are aquatic predators with extended larval development periods.
Neohydronomus
waterlettuce weevils
Neohydronomus is a genus of subaquatic weevils comprising three species native to South and Central America. All species are obligate specialists on waterlettuce (Pistia stratiotes), an invasive floating aquatic plant. The genus has been utilized as a biological control agent, with N. affinis successfully introduced to Florida in 1987 to manage waterlettuce infestations.
Neohydronomus affinis
Waterlettuce Weevil
Neohydronomus affinis is a subaquatic weevil native to South and Central America that has been deployed as a biological control agent against the invasive aquatic plant waterlettuce (Pistia stratiotes). First introduced to Florida in 1987, it has successfully established populations in peninsular Florida and Louisiana. The weevil's exoskeleton is covered in white scales and lacks water-resistant features, an unusual trait for an insect living in aquatic environments.
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.
Neophylax concinnus
Neophylax concinnus is a species of caddisfly (order Trichoptera) described by McLachlan in 1871. As a member of the family Uenoidae, it belongs to a group of case-building caddisflies whose larvae construct protective cases using silk and gathered materials. The species is recorded from North America, though specific details regarding its biology and ecology remain limited in the available literature.
Neophylax consimilis
Neophylax consimilis is a caddisfly species in the family Uenoidae, first described by Betten in 1934. Its larvae construct protective cases using silk and materials gathered from aquatic environments, with documented instances of exceptionally beautiful cases built from stones of varying colors. The species is found in North America and is part of the Nearctic fauna.
Neophylax kolodskii
Kolodski's caddisfly
Neophylax kolodskii is a species of caddisfly in the family Uenoidae (formerly placed in Thremmatidae), described by Parker in 2000. It is known from North America. Larvae of the genus Neophylax are case-building caddisflies that construct protective cases using silk and gathered materials such as sand, stones, and plant fragments.
Neophylax rickeri
Neophylax rickeri is a caddisfly species in the family Uenoidae, described by Milne in 1935. Larvae construct protective cases using silk and materials gathered from their aquatic environment. The species has been studied in northern California streams, where its life history characteristics have been documented.
Neoplea striola
pygmy backswimmer
Neoplea striola is a minute predaceous true bug in the family Pleidae, commonly known as the pygmy backswimmers. Adults measure approximately 1.5 mm in length. The species inhabits lentic freshwater habitats across Central and North America, including small fishless ponds and temporary water bodies, and has been observed to tolerate low oxygen conditions. It is an active visual predator that hunts zooplankton and small aquatic invertebrates using sight, vibrations, and possibly chemical cues. Research suggests it is univoltine, overwintering as adults with activity from March through November in temperate regions.
Neothremma alicia
Neothremma alicia is a species of caddisfly in the family Uenoidae, first described by Dodds & Hisaw in 1925. It belongs to the order Trichoptera, a group of aquatic insects whose larvae construct protective cases from silk and environmental materials. The genus Neothremma is part of the subfamily Uenoinae within the superfamily Limnephiloidea. Very little specific biological information is available for this species.
Nerophilus
mortarjoint casemakers
Nerophilus is a monotypic genus of caddisflies in the family Odontoceridae, containing the single described species N. californicus. These insects are commonly known as mortarjoint casemakers, a name reflecting their larval case-building behavior. The genus was established by Nathan Banks in 1899 and is endemic to western North America. As members of the order Trichoptera, adults possess hairy wings and aquatic larval stages.
Nerophilus californicus
California Mortarjoint Caddisfly
Nerophilus californicus is a species of caddisfly in the family Odontoceridae, commonly known as the California Mortarjoint Caddisfly. It was described by Hagen in 1861 and is native to North America. As a member of the order Trichoptera, it represents one of approximately 60 observation records documented on iNaturalist. The species belongs to a family whose larvae are typically associated with lotic (flowing water) habitats.
Neureclipsis crepuscularis
tube maker caddisfly
Neureclipsis crepuscularis is a species of tube-making caddisfly in the family Polycentropodidae. It is a small aquatic insect whose larvae construct silk tubes for shelter. The species is documented in North America, with records from the northeastern United States including Vermont. As a member of Polycentropodidae, it belongs to a family of predatory or parasitic caddisflies.
Nigronia fasciata
Banded Dark Fishfly
Nigronia fasciata is a species of dark fishfly in the family Corydalidae, order Megaloptera. Adults measure 22–28 mm in body length. The species occurs in the eastern United States and is not present in Canada. Like other fishflies, it has aquatic larval stages and terrestrial adults.
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.
Notonecta indica
backswimmer
Notonecta indica is a predatory aquatic true bug in the family Notonectidae, commonly known as backswimmers. The species has been documented in eastern Jamaica where it preys on mosquito larvae, particularly Aedes aegypti, with consumption rates increasing exponentially through nymphal development. Adults consume approximately 38 mosquito larvae daily under laboratory conditions. The species occurs across a broad geographic range including the Caribbean, Central America, North America, Oceania, and South America. Development from egg to adult takes approximately 36 days under warm conditions, with shorter development times than temperate backswimmer species attributed to higher temperatures and food availability.
Notonecta lunata
Backswimmer
Notonecta lunata is a species of backswimmer in the family Notonectidae. It is found in North America, with specific records from Vermont and other parts of the United States. Backswimmers in the genus Notonecta are aquatic insects known for swimming upside down and preying on small aquatic organisms.
Notonecta undulata
Grousewinged Backswimmer
Notonecta undulata, commonly known as the grousewinged backswimmer, is an aquatic true bug (Hemiptera: Notonectidae) found across North America. Adults measure 10–12 mm in length and are distinguished from other backswimmers by their 4-segmented antennae and wing pattern featuring a large black spot on the wing membrane median line. The species inhabits small ponds and lakes with slow-moving water, swimming upside down beneath the water surface to capture prey. It is a generalist predator with documented preference for mosquito larvae, and has been studied as a potential biological control agent.
Notonecta unifasciata
backswimmer
Notonecta unifasciata is a species of backswimmer in the family Notonectidae. It is distributed across Central America, North America, and South America. The species was described by Guérin-Méneville in 1857 and includes three recognized subspecies: Notonecta unifasciata andersoni, Notonecta unifasciata cochisiana, and the nominate subspecies Notonecta unifasciata unifasciata. As a member of the genus Notonecta, it shares the characteristic habit of swimming upside down near the water surface.
Odontoceridae
Mortarjoint Casemaker Caddisflies
Odontoceridae is a family of caddisflies (order Trichoptera) commonly known as mortarjoint casemakers. The family contains approximately 12 genera and at least 100 described species. Larvae are aquatic case-builders that typically construct cases from mineral particles such as sand and small stones. The family has a cosmopolitan distribution with representatives in North America, Europe, South America, and other regions. Adults are generally active during spring and summer months.
Oecetis
long-horned caddisflies
Oecetis is a genus of long-horned caddisflies in the family Leptoceridae, containing over 500 described species worldwide. Adults are distinguished by exceptionally long maxillary palps and an unbranched forewing M vein. Larvae inhabit freshwater environments including lakes, streams, and rivers with sandy substrates. The genus is among the largest and most widely distributed caddisfly genera, occurring in all faunal regions.
Oecetis inconspicua
Inconspicuous Long-horned Caddisfly
Oecetis inconspicua is a species of long-horned caddisfly in the family Leptoceridae. It is found in North America, with additional records from Brazil. The species belongs to a family characterized by larvae that construct portable cases and adults with notably elongated antennae.
Oemopteryx
winter stoneflies, willowflies
Oemopteryx is a genus of winter stoneflies in the family Taeniopterygidae, established by Klapálek in 1902. The genus comprises approximately six described species distributed primarily in the Nearctic region, with some records from Europe. Species are commonly known as willowflies, including the dark willowfly (O. contorta) and Canadian willowfly (O. glacialis). Recent taxonomic work has described additional Nearctic species from the southeastern United States using integrated morphological and molecular data.
Oemopteryx contorta
Dark Willowfly
Oemopteryx contorta, commonly known as the dark willowfly, is a species of winter stonefly in the family Taeniopterygidae. The species was described by Needham and Claassen in 1925. It is native to North America, with documented records from Alabama, Connecticut, Georgia, Kentucky, and Maine. As a member of the order Plecoptera, it belongs to a group of aquatic insects whose nymphal stages develop in freshwater environments.
Oligostomis ocelligera
giant casemaker
Oligostomis ocelligera is a species of giant casemaker caddisfly in the family Phryganeidae. It has been documented inhabiting acidic mine drainage environments in Pennsylvania, demonstrating tolerance to extreme conditions including low pH and high metal concentrations. The species is known from North America.
Omisus pica
Omisus pica is a species of non-biting midge in the family Chironomidae, first described by Townes in 1945. The genus Omisus belongs to the tribe Chironomini within the subfamily Chironominae. As with other chironomid midges, this species likely has an aquatic larval stage and terrestrial adult stage, though specific biological details remain poorly documented. The species is known from very few records, with only two observations documented on iNaturalist and no distribution records in GBIF.
Onocosmoecus unicolor
northern caddisfly
Onocosmoecus unicolor is a species of caddisfly in the family Limnephilidae, commonly known as the northern caddisfly. It was described by Banks in 1897. The species is distributed across North America and is part of the diverse caddisfly fauna associated with freshwater habitats.
Ophiogomphus
snaketails
Ophiogomphus is a genus of dragonflies in the family Gomphidae, commonly known as snaketails. The genus contains approximately 25 described species distributed across North America, Europe, and Asia. Most species exhibit green markings on club-shaped abdomens, with males typically displaying more prominent coloration. The genus includes both widespread species and localized endemics with restricted ranges.