Aquatic
Guides
Hesperocorixa minor
Hesperocorixa minor is a species of water boatman in the family Corixidae. It is a true bug in the order Hemiptera, characterized by aquatic habits typical of the Nepomorpha infraorder. The species was described by Abbott in 1913. Available records indicate a North American distribution, though detailed ecological and biological information remains limited.
Hesperocorixa vulgaris
water boatman
Hesperocorixa vulgaris is a species of water boatman in the family Corixidae, first described by Hungerford in 1925. This aquatic true bug is found in North America and is most active during spring through autumn. It feeds primarily on algae, which it sometimes stirs up from waterbeds. When threatened, it can deliver a painful bite.
Heterelmis
riffle beetles
Heterelmis is a genus of aquatic beetles in the family Elmidae, commonly known as riffle beetles. The genus includes several described species, with Heterelmis comalensis being particularly notable as an endangered species endemic to spring systems in Texas. Members of this genus are fully aquatic, inhabiting oxygen-rich flowing water environments where they feed on microbial biofilms. Some species have reduced or non-functional wings, limiting their dispersal ability and making them vulnerable to habitat degradation.
Heterelmis comalensis
Comal Springs riffle beetle
Heterelmis comalensis is a federally endangered aquatic beetle endemic to two spring systems in Texas. Described in 1988, this flightless species measures approximately 2 mm and inhabits shallow gravel substrates in spring riffles fed by the Edwards Aquifer. The species has been the focus of intensive conservation research, including captive breeding programs and studies on sexual dimorphism identification.
Huleechius marroni
Huleechius marroni is a species of riffle beetle (family Elmidae) described by Brown in 1981. It belongs to the genus Huleechius, a group of aquatic beetles adapted to flowing water habitats. The species is known from Middle America and North America. Like other elmids, it is presumed to inhabit freshwater streams and rivers, though specific ecological details remain poorly documented.
Hydaticus
Hydaticus is a genus of predatory diving beetles in the family Dytiscidae, comprising approximately 150 described species and 12 subspecies arranged in two subgenera: Hydaticus and Prodaticus. The genus has a cosmopolitan distribution spanning the Palearctic, Afrotropical, Nearctic, and Oriental regions. Members are aquatic predators found in freshwater habitats including streams, pools, and lentic environments.
Hydaticus rimosus
Hydaticus rimosus is a diving beetle species in the family Dytiscidae, first described by Aubé in 1838. The species belongs to the genus Hydaticus, a group of predatory aquatic beetles commonly found in freshwater habitats. It occurs in the Caribbean and Middle America based on documented distribution records.
Hydrachnoidea
water mites
Hydrachnoidea is a superfamily of aquatic mites commonly known as water mites. Members are exclusively freshwater dwellers, representing one of the most diverse radiations of arachnids into aquatic environments. The group includes several families with distinct morphological adaptations for underwater life.
Hydrobiomorpha casta
Hydrobiomorpha casta is a water scavenger beetle in the family Hydrophilidae. The species is distributed across the Caribbean, Central America, and southeastern North America. It is one of approximately 125 species in the genus Hydrobiomorpha, a group of aquatic beetles adapted to freshwater habitats.
Hydrochara
water scavenger beetles
Hydrochara is a genus of water scavenger beetles (Hydrophilidae) containing 23 species distributed across North America, Europe, Asia, and Africa. The genus was revised taxonomically in 1980, with 21 species recognized at that time and multiple synonymies established. Species in this genus are aquatic and have been studied for their potential role in biological control of mosquito larvae. At least one species, Hydrochara rickseckeri, is endemic to California.
Hydrochara rickseckeri
Ricksecker's Water Scavenger Beetle
Hydrochara rickseckeri is a rare, California-endemic water scavenger beetle in the family Hydrophilidae. It is one of the few Hydrochara species native to North America. The species was described by Horn in 1895 and remains poorly known due to its limited distribution and scarcity of observations.
Hydrochus granulatus
Hydrochus granulatus is a species of water scavenger beetle in the family Hydrochidae. The species was described by Blatchley in 1910 and is known from North America, with records from both the United States and Canada. It is sometimes treated as a member of the family Hydrophilidae in alternative classifications.
Hydrometra australis
water measurer
Hydrometra australis is a species of water measurer bug in the family Hydrometridae. It inhabits aquatic environments across the Caribbean, Central America, and North America. The species has been documented as a host for parasitic water mites, which can affect its population dynamics.
Hydrophorus chrysologus
Hydrophorus chrysologus is a species of long-legged fly in the family Dolichopodidae, subfamily Hydrophorinae. It belongs to a genus specialized for life on water surfaces, where adults skate across puddles, intermittent streams, and lake margins using surface tension. Like other dolichopodids, it is predatory on small insects and other arthropods. The species was described by Walker in 1849.
Hydroporus lapponum
Hydroporus lapponum is a predaceous diving beetle in the family Dytiscidae. The species has a broad Holarctic distribution, occurring across North America and the Palearctic region. It belongs to the genus Hydroporus, a large and diverse group of small diving beetles. The species was first described by Gyllenhal in 1808.
Hydrozetidae
Hydrozetidae is a family of aquatic oribatid mites (water mites) within the order Oribatida, established by Grandjean in 1954. The family contains at least one genus, Hydrozetes, with at least 20 described species. These mites are distinguished by adaptations to freshwater habitats, including a reduced bothridium lacking a sensillus, monodactylous legs, and the absence of pteromorphae. Fossil evidence from the Late Paleocene of Canada demonstrates the family's ancient aquatic association with submerged vegetation.
Hydryphantoidea
Hydryphantoidea is a superfamily of prostigmatan mites within Trombidiformes, comprising approximately 250 described species across six families. Members are predominantly aquatic or semiaquatic, inhabiting freshwater habitats worldwide. The group includes the families Hydryphantidae, Hydrodromidae, Rhynchohydracaridae, Thermacaridae, Ctenothyadidae, and Teratothyadidae.
Hygrobatidae
water mites
Hygrobatidae is a family of prostigmatan mites in the order Trombidiformes, commonly known as water mites. The family comprises approximately 78 genera and over 100 described species, though estimates vary. Members are primarily aquatic, inhabiting springs, streams, and running waters across multiple continents. The genus Hygrobates includes a well-studied species complex (fluviatilis-complex) with ten or more morphologically similar species. Some species exhibit parasitic associations with amphibians.
Lemnaphila
duckweed miner flies
Lemnaphila is a genus of shore flies in the family Ephydridae, commonly known as duckweed miner flies. The genus was established by Cresson in 1933 and contains seven described species distributed in the Neotropical region. At least one species, L. neotropica, is known to mine duckweeds (Lemna species), creating distinctive feeding damage on these aquatic plants. The genus has attracted attention due to the economic and ecological significance of its association with duckweed communities.
Lethocerinae
giant water bugs
Lethocerinae is a subfamily of giant water bugs within Belostomatidae, comprising large aquatic predatory insects distributed across the Palearctic, Oriental, and Australian regions. The subfamily includes two genera: Lethocerus and Kirkaldyia. Members are characterized by their large size—among the largest in Hemiptera—and are distinguished from other belostomatid subfamilies by morphological and genetic differences. Species within this group face conservation concerns in parts of their range due to harvesting for human consumption.
Lethocerus americanus
American giant water bug, electric light bug, toe biter, fish killer
Lethocerus americanus is a large aquatic true bug native to southern Canada and the northern United States. Adults measure 5–6 cm in length, with females averaging larger than males. The species is a generalist predator in freshwater habitats and is known for its powerful bite, which it uses to subdue prey and defend itself. It is attracted to electric lights at night, earning it the common name 'electric light bug.'
Lethocerus medius
giant water bug
Lethocerus medius is a giant water bug in the family Belostomatidae, distinguished by its substantial size and unique parental care behavior. Males reach 49–58 mm, while females are larger at 62–63 mm. Unlike related species in the subfamily Belostomatinae that brood eggs on their backs, males of this species exhibit postzygotic parental care by guarding eggs deposited on objects above the water surface, moistening them, shading them, and protecting them from predators. This species occurs across a broad range from the southern United States through Mexico to Central America and throughout the Caribbean.
Libellula jesseana
Purple Skimmer
Libellula jesseana, the purple skimmer, is a threatened dragonfly endemic to Florida, United States. Adults measure approximately 5 centimeters in length. The species is restricted to infertile, clear, sandy-bottomed lakes with specific shoreline vegetation, and is critically imperiled due to habitat degradation from human development.
Limnochares americana
Red Freshwater Mite
Limnochares americana is a species of freshwater mite in the family Limnocharidae, first described by Lundblad in 1941. It belongs to the order Trombidiformes, a group that includes many aquatic and terrestrial mites. As a member of the infraorder Hydrachnidia (water mites), this species is adapted to life in freshwater habitats. The common name "Red Freshwater Mite" reflects its aquatic ecology and likely coloration.
Limnohydrobius melaenus
Limnohydrobius melaenus is a species of water scavenger beetle in the family Hydrophilidae. It is found in eastern North America, ranging from the Canadian Maritime provinces west to the upper Midwest and south to the southeastern United States. The species is associated with aquatic and semi-aquatic habitats. Like other members of the genus, it is presumed to have aquatic larvae and terrestrial adults.
Liodessus
Liodessus is a genus of small diving beetles in the family Dytiscidae, tribe Bidessini. Species occur across the Americas from North America through the Andes to southern South America, with notable diversity in high-altitude wetlands and páramo ecosystems. Many species inhabit shallow, exposed pools and temporary water bodies, showing phenotypic plasticity in body form correlated with habitat permanence. The genus contains numerous species, with several new species described from the high Andes of Peru and Colombia in recent years. Taxonomic resolution relies heavily on male genital morphology.
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Liodessus affinis is a small predaceous diving beetle in the family Dytiscidae, first described by Say in 1823. The species belongs to a taxonomically challenging species complex that was revised in 1998, during which several former synonyms were elevated to species status. It is found in aquatic habitats across North America, with records from Canada and the United States. Like other members of the genus, it is a predator in freshwater ecosystems.
Listronotus anthracinus
underwater weevil
Listronotus anthracinus is a species of underwater weevil in the beetle family Curculionidae. It is distinguished from congeners by its aquatic habits. The species was originally described under the genus Macrops. Very little is known about its biology compared to better-studied relatives such as L. oregonensis (carrot weevil) and L. maculicollis (annual bluegrass weevil).
Listronotus appendiculatus
underwater weevil
Listronotus appendiculatus is an underwater weevil in the family Curculionidae. It is found in North America, with distribution records from Canada including Alberta, British Columbia, Manitoba, and New Brunswick. The species inhabits aquatic environments, distinguishing it from many congeneric species that are agricultural pests of terrestrial crops.
Listronotus caudatus
Listronotus caudatus is a species of underwater weevil in the beetle family Curculionidae. It is found in North America. The species has been recorded in multiple Canadian provinces including British Columbia, New Brunswick, Ontario, and Québec. Very little is known about its specific biology or ecology compared to better-studied congeners such as the carrot weevil (L. oregonensis) and annual bluegrass weevil (L. maculicollis).
Listronotus delumbis
underwater weevil
Listronotus delumbis is a species of underwater weevil in the beetle family Curculionidae. It is one of relatively few weevil species adapted to aquatic or semi-aquatic habitats. The species was described by Gyllenhal in 1834 and has been historically classified under the genus Listroderes as a synonym. Knowledge of its biology and ecology remains limited compared to better-studied Listronotus species.
Listronotus dietzi
Listronotus dietzi is a species of underwater weevil in the beetle family Curculionidae. It was described by O'Brien in 1979. The species is known from a very limited geographic range, with records restricted to Louisiana in the United States. Very little is known about its biology or ecology.
Listronotus frontalis
underwater weevil
Listronotus frontalis is a species of underwater weevil in the beetle family Curculionidae. It is found in North America, with records from Canada (Alberta, British Columbia, Ontario, Québec). The species was described by J.L. LeConte in 1876. Like other members of the genus Listronotus, it is associated with aquatic or semi-aquatic habitats.
Listronotus lodingi
Listronotus lodingi is a species of underwater weevil in the beetle family Curculionidae. It was originally described as Hyperodes lodingi by Blatchley in 1920. The species is currently recognized as a synonym of Hyperodes lodingi in some taxonomic databases, though it is listed under the genus Listronotus in other sources. Very little specific information is available about its biology or ecology.
Listronotus marshalli
Listronotus marshalli is a species of underwater weevil in the beetle family Curculionidae, described by O'Brien in 1981. It is found in North America and belongs to a genus that includes several aquatic or semi-aquatic species. The species is provisionally accepted in taxonomic databases.
Listronotus pallidus
Listronotus pallidus is an underwater weevil in the family Curculionidae, described by O'Brien in 1981. It is distinguished from other weevils by its aquatic habitat. The species is known from North America, though specific details about its biology and ecology remain poorly documented. Like other members of the genus Listronotus, it likely inhabits submerged vegetation in freshwater environments.
Listronotus porcellus
underwater weevil
Listronotus porcellus is an aquatic weevil in the family Curculionidae, known for its underwater lifestyle. It is one of several species in the genus Listronotus, which includes both aquatic and terrestrial weevils. The species has been documented in North America, including British Columbia and Québec in Canada. Relatively little is known about its specific biology compared to better-studied congeners such as L. maculicollis and L. oregonensis.
Listronotus squamiger
Listronotus squamiger is a species of underwater weevil in the family Curculionidae. It has been documented in aquatic habitats across North America, including the Canadian provinces of Alberta, British Columbia, Manitoba, and New Brunswick. The species belongs to a genus that includes several economically significant agricultural pests, though specific information about the biology and ecology of L. squamiger itself remains limited.
Listronotus turbatus
Listronotus turbatus is a species of underwater weevil in the family Curculionidae. It was described by O'Brien in 1981. The species is found in North America. Unlike several congeners, it is not known to be an agricultural pest.
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 terminatum terminatum
Maccaffertium terminatum terminatum is a subspecies of mayfly in the family Heptageniidae. Like other members of its genus, it exhibits the unique mayfly developmental trait of having a winged sub-adult stage (subimago) that requires one final molt to reach full adulthood. The subspecies is part of the Nearctic fauna, with records from North America. As an aquatic insect, its life cycle is tied to freshwater habitats, with nymphs developing in water before emerging as winged adults.
Macronychini
riffle beetles
Macronychini is a tribe of riffle beetles within the family Elmidae, first described by Gistel in 1848. The tribe comprises more than 20 genera and over 80 described species. Members of this tribe are aquatic beetles associated with running water habitats. The tribe is taxonomically well-established but individual species continue to be described, particularly from underexplored regions such as China.
Matus bicarinatus
Matus bicarinatus is a predaceous diving beetle in the family Dytiscidae. It belongs to the subfamily Matinae, a group of specialized diving beetles. The species is documented from North America, with records from Ontario, Canada. Knowledge of its biology remains limited due to few observations.
Megamelus flavus
Megamelus flavus is a species of delphacid planthopper in the family Delphacidae, described by Crawford in 1914. It belongs to the genus Megamelus, a group of planthoppers associated with aquatic and semi-aquatic habitats. Distribution records indicate presence in northern North America and parts of Asia.
Microvelia
small water striders, riffle bugs
Microvelia is a large genus of small semiaquatic bugs comprising at least 230 described species distributed worldwide. These insects inhabit nearshore areas of stagnant or slow-flowing freshwater, where they move on the water surface using surface tension. The genus exhibits wing dimorphism, with populations containing both fully winged (macropterous) and short-winged (brachypterous) individuals. Several subgenera have been recognized including Austromicrovelia, Barbivelia, Pacificovelia, and Picaultia, based on phylogenetic and morphological analyses.
Microvelia californiensis
Microvelia californiensis is a species of small water strider in the family Veliidae, described by McKinstry in 1937. The species is known from California and adjacent regions of western North America. Like other members of the genus, it inhabits the surface film of freshwater habitats. Very few observations of this species have been documented in public databases.
Myxophaga
Minute Bog and Skiff Beetles
Myxophaga is a small suborder of Coleoptera comprising approximately 65 described species across four extant families: Lepiceridae, Hydroscaphidae, Sphaeriusidae, and Torridincolidae. These beetles are among the smallest in the order, ranging from small to minute in size. All members are aquatic or semiaquatic, with many species inhabiting hygropetric environments—thin water films on rock surfaces in running water. The suborder is characterized by distinctive morphological features including clubbed antennae with fewer than nine segments, open mesocoxal cavities, and apically rolled hind wings in resting position.
Neargyractis
Neargyractis is a genus of aquatic moths in the family Crambidae, subfamily Acentropinae. The genus was established by W.H. Lange in 1956 during a revision of North American aquatic moths. It contains at least eight described species distributed primarily in the Americas.
Nectoporus
Nectoporus is a genus of diving beetles (family Dytiscidae) established by Guignot in 1950. It belongs to the subfamily Hydroporinae, a diverse group of small to medium-sized predatory aquatic beetles. Members of this genus are found in freshwater habitats, primarily in the Southern Hemisphere based on available distribution records. As with other dytiscids, they are aquatic predators with adaptations for underwater life including modified hind legs for swimming.
Neoelmis caesa
riffle beetle
Neoelmis caesa is a species of riffle beetle in the family Elmidae. It is found in North America. As a member of the Elmidae, it inhabits aquatic environments, specifically riffle habitats in streams and rivers. The species was first described by LeConte in 1874.