Aquatic-insects
Guides
Limnichidae
Minute Marsh-loving Beetles
Limnichidae is a family of small beetles in the superfamily Byrrhoidea, comprising at least 30 genera and 350 described species. The family exhibits considerable ecological diversity: while many species inhabit water-adjacent habitats such as riparian zones and coastal areas, others are fully terrestrial in leaf litter or arboreal environments. The subfamily Hyphalinae is uniquely specialized for intertidal marine habitats, with larvae capable of activity in seawater—a rarity among beetles. The oldest known fossils date to the mid-Cretaceous Burmese amber.
Limnophyes
Limnophyes is a genus of non-biting midges (Chironomidae) in the subfamily Orthocladiinae. Species occupy diverse aquatic and semi-aquatic habitats including springs, wetlands, and leaf mines. The genus has a Holarctic distribution with some species showing global ranges, and contains approximately 40 described species. Several species exhibit specialized ecological associations, including crenophily (spring-dwelling) and commensal leaf-mining behavior.
Limonia
Limonia is a genus of crane flies in the family Limoniidae, established by Meigen in 1803. The genus is taxonomically broad and serves as a provisional grouping for species that may require reclassification to other genera. Species of Limonia are found across multiple continents, with documented diversity in East Asia, Europe, and North America. The genus includes both widespread and regionally endemic species.
Lipogomphus
Lipogomphus is a genus of velvet water bugs in the family Hebridae, established by Berg in 1879. The genus contains at least four described species distributed in the New World. Members of this genus are small predatory aquatic insects associated with wet habitats.
Lytogaster excavata
Lytogaster excavata is a species of shore fly in the family Ephydridae, first described by Sturtevant and Wheeler in 1954. The genus Lytogaster belongs to a group of small flies commonly associated with aquatic or semi-aquatic habitats. Records indicate this species has been documented in natural history collections, though detailed biological information remains limited.
Macdunnoa
Macdunnoa is a genus of mayflies in the family Heptageniidae, established by Lehmkuhl in 1979. The genus belongs to the order Ephemeroptera, a group of aquatic insects known for their brief adult lifespan. Very few observations of this genus have been recorded, with only a single documented observation in iNaturalist. As a member of Heptageniidae, it is part of a diverse family of flat-headed mayflies commonly found in running water habitats.
Macromiidae
cruisers, skimmers
Macromiidae is a family of large dragonflies commonly called cruisers or skimmers, containing approximately 125 species in three genera (Epophthalmia, Macromia, Phyllomacromia). Adults are known for their distinctive flight pattern of patrolling straight down the middle of water bodies and roads. The family is widely distributed across the Holarctic, Afrotropical, Australasian, and Indo-Malayan regions, with highest diversity in East and Southeast Asia, North America, and sub-Saharan Africa. Females lack an ovipositor and deposit eggs by dipping their abdomen into water during flight.
Martarega
backswimmers
Martarega is a genus of backswimmers in the family Notonectidae, containing approximately 13-20 described species distributed throughout the Western Hemisphere from the southern United States to Argentina. The genus was established by White in 1879 and is classified within the tribe Nychiini. Brazil harbors the greatest diversity with 14 recorded species, though distributional gaps remain across 11 Brazilian states. Recent records have documented the first occurrence of the genus in the United States and expanded known ranges in eastern Brazil.
Maruina
Maruina is a genus of moth flies (Psychodidae) containing approximately 39 described species. The genus is unique among Psychodidae in being strictly aquatic, with larvae and pupae specially adapted for life in flowing water. It is restricted to the Western Hemisphere, with the majority of species occurring in the Neotropical region. The genus is divided into two subgenera: Aculcina and Maruina.
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.
Megaloptera
alderflies, dobsonflies, fishflies
Megaloptera is a small order of holometabolous insects containing approximately 300 described species across two extant families: Corydalidae (dobsonflies and fishflies) and Sialidae (alderflies). Adults are characterized by large, membranous wings that fold over the abdomen, and many species have short adult lifespans during which they do not feed. Larvae are exclusively aquatic, predatory, and serve as important indicators of stream health due to their sensitivity to pollution. The order was formerly classified within Neuroptera but is now recognized as a distinct order within the superorder Neuropterida.
Megarcys
springflies
Megarcys is a genus of springflies in the family Perlodidae, comprising approximately 11 described species. The genus was established by Klapálek in 1912. Species occur primarily in cold-water habitats across northern regions of North America and Asia. Megarcys belongs to the tribe Arcynopterygini within the subfamily Perlodinae.
Merragata
velvet water bugs
Merragata is a genus of small aquatic true bugs in the family Hebridae, commonly known as velvet water bugs. The genus contains seven described species distributed primarily in tropical and subtropical regions. Members of this genus inhabit moist, vegetated shoreline habitats where they prey on small invertebrates.
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.
Micracanthia
Micracanthia is a genus of shore bugs in the family Saldidae, established by Reuter in 1912. The genus comprises approximately 15 described species. These insects belong to the true bugs (Heteroptera) and are part of the Saldoidini tribe within the Saldinae subfamily. The genus has been documented in comparative taxonomic studies regarding its relationship to the closely related genus Saldula.
Micropsectra
non-biting midges
Micropsectra is a genus of non-biting midges in the family Chironomidae, tribe Tanytarsini, described by Kieffer in 1909. The genus contains over 170 described species, though taxonomic revision indicates approximately 83 valid species with many former species reassigned to other genera. Species are primarily distributed across the Holarctic region, with most occurring in the Palaearctic and Nearctic regions and limited representation in the northern Oriental region. The genus forms part of the Micropsectra series, a monophyletic group within Tanytarsini that includes Rheotanytarsus, Parapsectra, Krenopsectra, and Paratanytarsus.
Narpus
riffle beetles
Narpus is a genus of riffle beetles in the family Elmidae, established by Casey in 1893. The genus contains three described species: Narpus angustus, Narpus arizonicus, and Narpus concolor. These beetles are restricted to western North America and are strongly associated with clean, fast-flowing stream habitats. As members of the Elmidae family, they are adapted to life in running water environments.
Natarsia
Natarsia is a genus of non-biting midges in the bloodworm family Chironomidae, established by Fittkau in 1962. It is the sole genus in the monotypic tribe Natarsiini within the subfamily Tanypodinae. The genus contains six described species distributed across the Holarctic region. Members are aquatic insects with larvae that develop in freshwater habitats.
Naucoridae
creeping water bugs, saucer bugs
Naucoridae is a family of aquatic predatory true bugs comprising approximately 400 species in 46 genera across five subfamilies. Members are commonly known as creeping water bugs or saucer bugs due to their dorsoventrally flattened, oval body shape. They inhabit freshwater environments worldwide with greatest diversity in tropical regions, ranging from still waters to torrential streams. Most species are lotic, occurring in flowing waters rather than lentic habitats. They are predatory, feeding on other small invertebrates using piercing-sucking mouthparts.
Nemoura
spring stoneflies
Nemoura is a genus of spring stoneflies in the family Nemouridae, with more than 190 described species. The genus belongs to the subfamily Nemourinae within the superfamily Nemouroidea. Species in this genus are part of the EPT (Ephemeroptera, Plecoptera, Trichoptera) complex, a group of aquatic insects with significant ecological importance in freshwater ecosystems.
Nemouridae
spring stoneflies, brown stoneflies, forestflies, tiny winter blacks
Nemouridae is a family of stoneflies (Plecoptera) comprising over 700 described species, primarily distributed in the Holarctic region. Members are commonly known as spring stoneflies, brown stoneflies, or forestflies, and are important indicators of water quality in aquatic ecosystems. The family is characterized by small size, with adults typically measuring 5–8 millimeters in body length. Nemouridae occupy diverse flowing-water habitats, though they are most prevalent in smaller streams.
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.
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.
Neophylax mitchelli
Neophylax mitchelli is a North American caddisfly species in the family Uenoidae. Like other members of its genus, it has aquatic larvae that construct protective cases from silk and environmental materials. The species was described by Carpenter in 1933.
Neoplasta
Neoplasta is a genus of dance flies in the family Empididae, subfamily Empidinae, tribe Hemerodromiini. The genus contains approximately 27 described species distributed across the Americas, with records from North and South America. At least one species, N. parahebes, has been studied in detail and exhibits a life cycle tied to submerged decaying wood in freshwater streams, with predatory habits in both adult and larval stages.
Neothremma
Neothremma is a genus of caddisflies in the family Uenoidae, established by Dodds and Hisaw in 1925. The genus contains at least one described species, Neothremma siskiyou, known as the Siskiyou caddisfly, which is found in California. As a member of the Uenoidae, it belongs to a family of case-making caddisflies associated with cool, flowing waters.
Nepa
water scorpion
Nepa is a genus of aquatic true bugs in the family Nepidae, commonly known as water scorpions. These insects inhabit freshwater environments and are characterized by their elongated bodies, raptorial forelegs adapted for capturing prey, and a long respiratory siphon extending from the abdomen. The genus belongs to the subfamily Nepinae and is distinguished from related genera primarily by morphological features of the pronotum and respiratory siphon structure.
Nepoidea
Nepoidea is a superfamily of aquatic true bugs comprising two families: Belostomatidae (giant water bugs) and Nepidae (water scorpions). These are the largest-bodied members of the infraorder Nepomorpha and function as top predators in freshwater ecosystems. A distinctive morphological trait is the reduction and concealment of antennae in grooves behind the eyes, an adaptation to submerged aquatic life. The antennal sensilla exhibit remarkable structural diversity, with 11 morphological types identified including mechanosensilla, thermo-hygrosensilla, and olfactory sensilla that facilitate environmental sensing and prey detection.
Nepomorpha
true water bugs, water bugs
Nepomorpha is an infraorder of aquatic true bugs (Hemiptera: Heteroptera) comprising approximately 2,000 species worldwide. Members are characterized by reduced, weakly muscled antennae typically concealed against the head, and absent or vestigial ocelli. Most species inhabit freshwater environments, with the exception of the superfamily Ochteroidea, which occupies riparian zones along water margins. The group includes diverse forms such as giant water bugs, water scorpions, water boatmen, and backswimmers.
Nigronia
Dark Fishflies
Nigronia is a genus of megalopteran insects commonly known as dark fishflies. The genus contains two species, Nigronia serricornis and Nigronia fasciata, distinguished primarily by wing pattern. Adults are medium-sized insects measuring 20-30 millimeters in length. The genus belongs to the family Corydalidae, which includes dobsonflies and fishflies.
Nymphomyiidae
nymph flies
Nymphomyiidae are a family of minute (approximately 2 mm), delicate flies with highly reduced morphology. They are considered among the most archaic living Diptera, sometimes placed in their own suborder Archidiptera. Larvae are strictly aquatic, inhabiting cold, fast-flowing streams in northern and high-altitude regions. Adults are short-lived, non-feeding, and form aggregative swarms; their wings fracture at the base after mating. The family contains approximately one dozen extant species, currently classified in the single genus Nymphomyia.
Ostrocerca
forestflies
Ostrocerca is a genus of spring stoneflies (Plecoptera) in the family Nemouridae, containing six described species distributed in eastern North America. Members are small to medium-sized stoneflies commonly known as forestflies. The genus was established by Ricker in 1952. Species are distinguished by subtle morphological differences in wing venation and genitalia.
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.
Paralimna
shore flies
Paralimna is a genus of shore flies in the family Ephydridae, first described by Loew in 1862. The genus contains at least 90 described species. These small flies are associated with aquatic or semi-aquatic environments, consistent with the ecological habits of the family Ephydridae.
Parametriocnemus
Parametriocnemus is a genus of non-biting midges in the family Chironomidae, subfamily Orthocladiinae. The genus has a cosmopolitan distribution, occurring on all continents except Antarctica. It was established by Goetghebuer in 1931. Species-level identification of adult males in the Nearctic region requires examination of genitalia and other morphological features detailed in specialized taxonomic keys.
Paraphaenocladius
non-biting midges
Paraphaenocladius is a genus of non-biting midges in the family Chironomidae, subfamily Orthocladiinae. Originally described from Europe, the genus has since been documented in the Neotropical region, with records from Costa Rica, Brazil, and other Central and South American localities. Species in this genus are associated with aquatic and semi-terrestrial habitats, particularly springs and mossy margins.
Parapoynx
China-mark moths
Parapoynx is a genus of aquatic moths in the family Crambidae, subfamily Acentropinae, established by Jacob Hübner in 1825. The genus contains approximately 60 described species distributed across Asia, Africa, Europe, and the Americas. Many species have aquatic or semi-aquatic larvae that feed on submerged aquatic plants. Several species are of economic importance as pests of rice and other aquatic crops, while others have been investigated as potential biological control agents for invasive aquatic weeds such as hydrilla.
Paratendipes
non-biting midges
Paratendipes is a widespread genus of non-biting midges in the family Chironomidae, established by Kieffer in 1911. The genus belongs to the 'Microtendipes' group within tribe Chironomini. Species occur in Europe, North America, Australia, and New Zealand. Larvae are aquatic and inhabit freshwater systems. Adult males possess distinctive genitalic structures useful for species identification.
Pediciidae
Hairy-eyed Crane Flies
Pediciidae, commonly known as hairy-eyed crane flies, is a family of about 500 species worldwide. They are medium-sized to large flies (5–35 mm) closely related to true crane flies (Tipulidae). The family is distinguished by pubescent compound eyes with short erect hairs between the facets, a trait absent in related families. They occupy diverse habitats but are particularly associated with clean, cold aquatic environments. The family was established as a separate lineage from Tipulidae based on morphological and molecular evidence, representing one of two primary lineages within the superfamily Tipuloidea.
Pelonomus
long-toed water beetles
Pelonomus is a genus of long-toed water beetles in the family Dryopidae, first described by Erichson in 1847. The genus contains approximately five described species distributed primarily in the Americas. These beetles are associated with aquatic or semi-aquatic habitats. Members of this genus are characterized by elongated tarsi adapted for clinging to submerged substrates.
Peltoperlidae
roach-like stoneflies, roachflies
Peltoperlidae is a family of stoneflies comprising 11 genera and approximately 46 known species. Larvae are dorsoventrally flattened with expanded thoracic plates, giving them a distinctive roach-like appearance. The family exhibits semivoltine life cycles lasting one to two years, with adult emergence typically occurring from April through June. Members are classified as shredder-detritivores, playing a significant role in leaf litter decomposition in lotic systems.
Pentaneura
Pentaneura is a genus of non-biting midges in the family Chironomidae, subfamily Tanypodinae. These aquatic insects are members of the tribe Pentaneurini and are found in freshwater habitats. The genus was established by Philippi in 1865 and contains predatory species whose larvae inhabit various aquatic environments.
Perlodidae
perlodid stoneflies, stripetails, springflies, Stripetail and Springfly Stoneflies
Perlodidae is a family of stoneflies comprising at least 50 genera and over 350 species, with fossil records extending to the Triassic. Adults are commonly known as stripetails or springflies and typically emerge from April to June. The family is characterized by larvae with flattened bodies, patterned heads and thoraces, long tails, and divergent hind wing pads that lack the branching thoracic gills found in similar stonefly families.
Perlodinae
Springflies
Perlodinae is a subfamily of stoneflies in the family Perlodidae, first described by Klapálek in 1909. The subfamily comprises at least 20 genera and approximately 60 described species. Perlodinae is distributed across Asia and other regions, with notable diversity in China. The tribal classification within Perlodinae remains under discussion, with three recognized tribes but ongoing questions about their validity.
Petrophila
Petrophila is a genus of aquatic moths in the family Crambidae, described by Lansdown Guilding in 1830. The genus comprises approximately 30-40 species distributed primarily in North America. Larvae are fully aquatic and inhabit flowing water systems, where they graze on algae and diatoms. Adults are diurnal and typically found resting on rocks near water bodies. The genus has become a notable subject of citizen science research due to the cryptic nature of many species, which can be difficult to distinguish without detailed examination.
Philygria
shore flies
Philygria is a genus of shore flies in the family Ephydridae, established by Stenhammar in 1844. The genus contains at least 40 described species, with 44 species listed in major databases. These small flies are associated with aquatic and semi-aquatic habitats.
Phryganea cinerea
Rush Sedge Caddisfly
Phryganea cinerea is a caddisfly species in the family Phryganeidae, one of the most primitive families of tube-case-building caddisflies. Larvae are characterized by abundant setae (bristles) across the body surface, which play a significant role in sensory perception and behavior given their poor eyesight. The species has been studied for its tactile responses, with setae on different body regions producing distinct directional responses to mechanical stimulation.
Phryganeidae
Giant Casemaker Caddisflies
Phryganeidae is a family of large caddisflies comprising approximately 16 genera and at least 80 described species. Adults are among the largest caddisflies, with wingspans reaching 40 mm or more. Larvae are aquatic case-makers, constructing distinctive cylindrical cases from plant fragments arranged in ring-like patterns. The family occurs across the Holarctic region, with species inhabiting diverse freshwater habitats from cool mountain streams to acidic bog pools.
Platystoechotes lineatus
Platystoechotes lineatus is a species of spongillafly in the family Sisyridae, a group of lacewing relatives specialized for feeding on freshwater sponges. The species is native to western North America. Like other sisyrids, its larvae are aquatic predators with piercing-sucking mouthparts adapted for extracting fluids from sponge tissue. Adults are terrestrial and typically found near streams or lakes where their larval hosts occur.