Aquatic
Guides
Acentropinae
China-mark Moths
Acentropinae is a subfamily of aquatic moths within the family Crambidae, comprising approximately 730 species in 78 genera. It represents the largest lineage of moths with at least one life stage adapted to aquatic environments. The subfamily includes two tribes: Argyractini and Acentropini (the latter including the former Nymphulinae). Larvae are aquatic and feed on submerged vegetation, while adults are terrestrial but associated with wetland habitats.
Acentropini
China-mark moths
Acentropini is a tribe of aquatic moths within the family Crambidae, commonly known as china-mark moths. Adults are small to medium-sized moths with wingspans typically ranging from 15–35 mm. The tribe is distinguished by larvae that are fully aquatic, breathing through gills and feeding on submerged aquatic plants. These moths are found across temperate and tropical regions worldwide, with highest diversity in the Old World tropics.
Acilius abbreviatus
Abbreviated Predaceous Diving Beetle
Acilius abbreviatus is a predaceous diving beetle in the family Dytiscidae. It is found in North America, with records from Alberta and British Columbia in Canada. As a member of the genus Acilius, it is an aquatic predator inhabiting freshwater environments.
Acilius athabascae
Athabascan Predaceous Diving Beetle
Acilius athabascae is a species of predaceous diving beetle described by Larson in 1975. It belongs to the genus Acilius, a group of large diving beetles known for their streamlined bodies and predatory habits in aquatic environments. The species is found in North America, with records from Alberta and British Columbia in Canada.
Acilius sylvanus
Woodland Predaceous Diving Beetle
Acilius sylvanus is a predaceous diving beetle described by Hilsenhoff in 1975. It belongs to the family Dytiscidae, a group of aquatic beetles adapted for underwater predation. The species is known from forested wetland habitats in North America.
Acneus
water-penny beetles
Acneus is a genus of water-penny beetles (family Psephenidae) containing four described species. The genus is characterized by flattened, oval larvae that cling to submerged rocks in flowing water. Adults are terrestrial and rarely encountered. The genus was established by Horn in 1880 and is restricted to western North America.
Acneus quadrimaculatus
water penny beetle
Acneus quadrimaculatus is a species of water penny beetle in the family Psephenidae. It is endemic to the United States with confirmed records from California and Oregon. Adults are found in riparian vegetation near aquatic habitats. The species was described by Horn in 1880.
Aeshna palmata
Paddle-tailed Darner
Aeshna palmata, commonly known as the Paddle-tailed Darner, is a species of dragonfly in the family Aeshnidae. It is widely distributed across western Canada and the western United States. The species is named for its distinctive paddle-shaped cerci (appendages at the tip of the abdomen). It inhabits lakes, ponds, and slow-moving streams, typically with dense vegetation along the shorelines. The species was first scientifically described by Hermann Hagen in 1856.
Agabus
Agabus is a large genus of predatory aquatic beetles in the family Dytiscidae, established by William Elford Leach in 1817. Adults range from 5 to 14 mm in length. The genus has a primarily Holarctic distribution, with limited representation in the Afrotropic and Neotropic realms. Some species are of conservation concern, with A. clypealis, A. discicollis, and A. hozgargantae listed as endangered by the IUCN.
Agabus ajax
Agabus ajax is a predaceous diving beetle in the family Dytiscidae. The species was described by Fall in 1922. It is known from North America, with records from Alberta and British Columbia in Canada. As a member of Agabus, it is an aquatic predator.
Agabus antennatus
Agabus antennatus is a species of predaceous diving beetle in the family Dytiscidae, first described by Leech in 1939. It is found in North America, with records from Alberta and British Columbia in Canada. As a member of the genus Agabus, it is an aquatic predator inhabiting freshwater environments.
Agabus canadensis
Agabus canadensis is a predaceous diving beetle in the family Dytiscidae, described by Fall in 1922. It is found in North America, with records from Canada (Alberta, British Columbia) and the United States. As a member of the genus Agabus, it is an aquatic predator inhabiting freshwater environments.
Agabus clavicornis
Agabus clavicornis is a predaceous diving beetle in the family Dytiscidae. It is distributed across the Holarctic region, occurring in both North America and the Palearctic. The species was described by Sharp in 1882. Like other members of the genus Agabus, it is an aquatic predator.
Agabus crassipes
Agabus crassipes is a diving beetle species in the family Dytiscidae, described by Fall in 1922. It is native to North America, with records from western Canada including Alberta and British Columbia. As a member of the genus Agabus, it is an aquatic predator inhabiting freshwater environments. The specific epithet 'crassipes' refers to its stout or thick legs.
Agabus falli
Agabus falli is a species of predaceous diving beetle in the family Dytiscidae. It is known from North America, with records from Alberta and Manitoba in Canada. As a member of the genus Agabus, it is an aquatic predator inhabiting freshwater environments. The species was described by Zimmermann in 1934.
Agabus punctulatus
Agabus punctulatus is a predaceous diving beetle in the family Dytiscidae. It inhabits freshwater environments and is distributed across North America, with records from western Canada including Alberta and British Columbia. As a member of the genus Agabus, it is part of a diverse group of aquatic beetles adapted to life in ponds, lakes, and slow-moving waters.
Agabus taeniolatus
Agabus taeniolatus is a species of predaceous diving beetle in the family Dytiscidae. It belongs to the large genus Agabus, which contains numerous aquatic beetle species found primarily in the Holarctic region. This species is documented from North America and shares the general ecological characteristics of the genus as an aquatic predator in freshwater habitats.
Agabus tristis
Agabus tristis is a predaceous diving beetle in the family Dytiscidae. It belongs to the tristis species group, which has a Holarctic distribution. The species occurs in North America and the Palearctic region. It is one of two North American members of the tristis group, alongside A. leptapsis.
Allocapnia rickeri
Midwest Snowfly
Allocapnia rickeri is a small winter stonefly in the family Capniidae, commonly known as the Midwest Snowfly. It is one of numerous small, dark stoneflies in the genus Allocapnia that emerge during cold months when few other insects are active. The species has been documented across the central and eastern United States. Like other capniids, it is associated with clean, cold streams and is an important indicator of water quality.
winter-stoneflybioindicatorcoldwaterPlecopteraCapniidaeAllocapnialoticemergencebrachypteryapterygenitalia-identificationFrison-1942Midwestsoutheastern-USclean-water-indicatorJanuary-Marchsmall-stoneflywingless-femalestream-insectshreddergathererseasonal-resourcewater-qualityaquatic-insectterrestrial-adultshort-lived-adultovipositionsubmerged-eggshigh-dissolved-oxygenlow-temperaturecentral-USeastern-USAlabamaArkansasDelawareGeorgiaIllinoishexapodhemimetabolousEuholognathaNemouroideaArctoperlariaInsectaArthropodaAnimaliaGBIFCatalogue-of-LifeiNaturalistNCBItaxonomyaccepted-species1942FrisonRickerMidwest-Snowflysnowflysmall-dark-stoneflyclean-streamsriverswell-oxygenatedlotic-habitatcold-monthswinter-activitywing-reductionfemale-apterymale-flightepiproctparaproctterminaliataxonomic-revisioncongenersdistribution-recordsobservations9-observationseukaryotemetazoanarthropodinsectstoneflywinter-emergingJanuaryFebruaryMarchcold-weathernear-freezingbelow-freezingwater-surfacesubmerged-substratesallochthonous-organic-materialstream-ecosystemsseasonal-food-resourceinsectivorous-birdspredatorsscarce-preyunpollutedno-economic-importancestream-monitoringwater-quality-indicatorhigh-quality-coldwatermicroscopic-examinationtaxonomic-keysmale-terminaliareliable-separationgenitalic-examinationoverlapping-distributionsimilar-habitatsmall-sizeunder-10-mmbody-lengthreduced-wingsabsent-wingsfully-developed-wingsspecific-identificationpublished-descriptionsillustrationssubsequent-revisionscharacteristicfamily-Capniidaecommon-nameextended-nymphal-periodone-to-two-yearsshort-liveddoes-not-feedaquatic-nymphclean-cold-streamslow-temperaturesyear-roundwinter-monthsJanuary-through-Marchfamilycentered-Midwestextends-southeasternUnited-Statesdocumentedappearsmost-reliablydistinguishedsubtle-differencesterminal-abdominal-structuresshould-be-comparedagainstpublishedsubsequentgenus-levelcharacterizedreducedabsentfemalesfully-developedmalesrequires-examinationmale-genitaliastructureparaproctsreliableseparationoverlapssimilarmanyexternallydefinitivereliesmicroscopicexaminationcomparisonkeysusedbiologicalindicatorprogramspresenceindicatescoldconditionsno-directeconomicimportanceshreddersgatherersprocessingallochthonousorganicmaterialstreamecosystemsseasonalfoodresourceinsectivorousbirdsotherwhenalternativepreyscarceserveshigh-qualityhabitatsdevelopmentaquaticnymphalstagesterrestrialadultstagenymphsdevelopstreamsextendedperiodlikelyonetwoyearsbasedrelatedspeciesadultsdo-notfeedactiveduringweatherairtemperaturesmaynearbelowfreezingwingedcapableflightwinglessshort-wingedremainwatersurfacematingoccurwinterenteringdepositeggssubmergedsubstratessmallcommonlyknownnumerousdarkemergefewinsectscentraleasternassociatedcleanimportantundermmbodylengthmembersgenuswingspossessfullydevelopedspecificidentificationlevelwithinrequiresmalegenitaliaparticularlymostreliablysubtledifferencestheseterminalabdominalstructuresshouldcompareddescriptionstaxonomicrevisionswinter-emergingmaintainlowhighdissolvedoxygenlevelsthroughoutyearUnitedStatesdistributioncenteredextendssoutheasternmonthstypicallythroughthisactivitygivesrisecommonnamedonotprovidesqualitymonitoringnodirecthabitatmorphologysizegenitalicAmbrysus
creeping water bugs, saucer bugs
Ambrysus is a genus of creeping water bugs (family Naucoridae) containing more than 90 described species. These aquatic insects are found primarily in running streams across the New World, from northern North America to Argentina, with greatest diversity in Mexico. They possess flattened, rounded bodies and powerful claws for clinging to rocks in turbulent water. The genus includes two subgenera: Ambrysus (Syncollus) and Ambrysus (Ambrysus).
Ambrysus californicus
California creeping water bug
Ambrysus californicus is a species of creeping water bug in the family Naucoridae. It was described by Montandon in 1897. The species is native to North America and belongs to the subfamily Cryphocricinae, commonly known as saucer bugs due to their round, flat body shape. Like other members of the genus Ambrysus, it is an aquatic insect adapted to life in running streams.
Ambrysus circumcinctus
creeping water bug
Ambrysus circumcinctus is a species of creeping water bug in the family Naucoridae, distributed across Central America and North America. As a member of the subfamily Cryphocricinae, it inhabits aquatic environments including running streams. The genus Ambrysus is widespread in the New World, with its greatest diversity in Mexico. Like other naucorids, this species has adaptations for clinging to substrates in flowing water.
Ambrysus hungerfordi
A creeping water bug in the family Naucoridae, described by Usinger in 1946. It belongs to the genus Ambrysus, which is widespread in the New World from northern North America to Argentina, with greatest diversity in Mexican running streams. Like other members of Cryphocricinae, it is aquatic in both nymphal and adult stages.
Ambrysus lunatus
creeping water bug
Ambrysus lunatus is a species of creeping water bug in the family Naucoridae. It occurs in Central America and North America. The subspecies A. lunatus lunatus has been described with documented immature stages. Like other members of the genus Ambrysus, it is an aquatic predator inhabiting running streams.
Ambrysus pudicus
creeping water bug, saucer bug
Ambrysus pudicus is a species of creeping water bug (family Naucoridae) described by Carl Stål in 1862. It belongs to the diverse New World genus Ambrysus, which is distributed from northern North America to Argentina with highest diversity in Mexico. Like other members of its family, it is an aquatic predator inhabiting running streams. The specific epithet 'pudicus' (Latin for 'bashful' or 'modest') is shared with the unrelated pitcher plant Nepenthes pudica, which was named for its hidden underground traps.
Amphizoa
troutstream beetles
Amphizoa is a monogeneric genus of aquatic beetles, the sole representative of the family Amphizoidae. These beetles are commonly called troutstream beetles due to their association with cold, flowing mountain waters. The genus contains five known species, with three distributed in western North America and two in the eastern Palearctic region (China and North Korea). Adults and larvae are predatory, feeding primarily on stonefly larvae. When disturbed, adults release a yellowish, cantaloupe-scented fluid from the anus as a chemical defense.
Amphizoa lecontei
Trout-stream beetle
Amphizoa lecontei is an aquatic beetle species in the family Amphizoidae, commonly known as the trout-stream beetle. Adults measure 11.5–16 mm in body length and possess a diagnostic carina on the fifth interval of the elytron. The species is restricted to western North America, with concentrations in the Rocky Mountains. It is one of few beetles in its family and represents a distinctive lineage of stream-dwelling coleopterans.
Anabolia
Anabolia is a genus of northern caddisflies in the family Limnephilidae, containing approximately 18 described species. Species within this genus inhabit both temporary and permanent aquatic environments, with some species adapted to fluctuating water levels. Larvae exhibit rapid growth rates and extended hatching periods. Adults of some species use sex pheromones for mate attraction.
Anacaenini
Anacaenini is a tribe of small aquatic beetles in the family Hydrophilidae, containing 256 species across 6 genera. Members inhabit freshwater environments and are characterized by their compact body form and aquatic adaptations. The tribe was established by Hansen in 1991 and is classified within the subfamily Hydrophilinae.
Ancyronyx
spider water beetles, spider riffle beetles
Ancyronyx is a genus of aquatic riffle beetles in the family Elmidae, commonly known as spider water beetles or spider riffle beetles. The genus comprises 21 described species distributed across North America, South Asia, China, and Southeast Asia, with the Philippines recognized as a center of diversity containing 11 endemic species. Members are obligate inhabitants of lotic freshwater environments, where both adults and larvae cling to submerged substrates using their elongated legs and strong claws. The genus is notable for its potential use as a bioindicator of water quality due to its sensitivity to pollution and oxygen levels.
Anoplius depressipes
Anoplius depressipes is a spider wasp in the family Pompilidae, notable for its specialized hunting of fishing spiders in the genus Dolomedes. The species exhibits remarkable aquatic adaptations, including the ability to walk on water and dive underwater for several minutes to capture prey that attempts to escape beneath the surface. This wasp represents a striking example of predator-prey coevolution with semi-aquatic spiders.
Apsectrotanypus johnsoni
Apsectrotanypus johnsoni is a species of non-biting midge in the family Chironomidae, subfamily Tanypodinae. It was described by Coquillett in 1901. As a member of the tribe Macropelopini, it belongs to a group of predatory midges whose larvae inhabit aquatic environments. The species is documented in the Catalogue of Life and GBIF as an accepted taxon, with 25 observations recorded on iNaturalist.
Apsilops
Apsilops is a genus of ichneumonid wasps in the subfamily Cryptinae, containing approximately nine described species. Members are parasitoids of lepidopteran larvae, with documented associations including aquatic crambid moths and rice pests. The genus includes both aquatic and terrestrial species, reflecting diverse habitat specializations among its members.
Arcola
Arcola is a genus of snout moths (Lepidoptera: Pyralidae) in the subfamily Phycitinae, described by Shaffer in 1995. The genus includes species associated with aquatic vegetation, most notably Arcola malloi (Alligatorweed Stem Borer), which has been employed as a biological control agent for the invasive aquatic weed alligatorweed (Alternanthera philoxeroides) in the United States. The genus belongs to a diverse group of pyralid moths whose larvae typically feed on plant material.
Argyractini
Argyractini is a tribe of aquatic moths within the subfamily Acentropinae (Crambidae). The tribe includes several genera of small to medium-sized moths whose larvae are adapted to life in freshwater habitats. Adults are generally nocturnal and are attracted to light. The group is primarily distributed in the New World, with most species occurring in the Neotropical region.
Atherix lantha
watersnipe fly
Atherix lantha is a species of watersnipe fly in the family Athericidae. The larvae are aquatic, piercing-sucking predators that feed on other aquatic invertebrates. The species has a univoltine life cycle with overwintering fifth-instar larvae. Mass egg-laying behavior results in large aggregations of dead females attached to egg masses.
Atractelmis wawona
Wawona Riffle Beetle
Atractelmis wawona is a species of riffle beetle in the family Elmidae, described by Chandler in 1954. The common name 'Wawona Riffle Beetle' references Wawona, a location in California's Sierra Nevada. Like other elmids, it inhabits aquatic environments with flowing water. Very few observations or detailed studies of this species have been published.
Atrichomelina pubera
Atrichomelina pubera is a sciomyzid fly whose larvae are aquatic or semi-aquatic predators of freshwater snails. The species has been successfully reared in laboratory conditions, enabling documentation of its complete immature stages and feeding behavior. Its biology was formally described in a 1960 study focusing on life history and developmental morphology.
Bagoinae
Bagoinae is a subfamily of weevils (Curculionidae) containing the genus Bagous and related genera. Members are primarily associated with aquatic and semi-aquatic habitats, though some occupy terrestrial environments. The group has been variously classified, with some treatments placing it within Molytinae. The subfamily includes approximately 130 species in the Palaearctic region, with the genus Bagous distributed globally except Central and South America.
Bagous
Bagous is a genus of semi-aquatic weevils in the family Curculionidae containing at least 360 described species. Many species are associated with aquatic or semi-aquatic habitats, with several species developed as biological control agents for invasive aquatic plants, particularly Hydrilla verticillata. The genus includes both native and introduced species with varying degrees of host specificity. Larvae typically develop within plant stems while adults feed on stems and leaves.
Bagous bituberosus
Bagous bituberosus is a species of true weevil in the family Curculionidae, first described by John Lawrence LeConte in 1876. The species is known from North America, with confirmed records from Canada and the United States. Like other members of the genus Bagous, it is associated with aquatic or semi-aquatic habitats. The specific epithet 'bituberosus' refers to a morphological feature of two tubercles or protuberances.
Bellura anoa
Arrowhead Diver Moth
Bellura anoa is a North American moth in the family Noctuidae. Like other members of its genus, it is associated with aquatic habitats during its larval stage. The species is poorly studied compared to its congener Bellura melanopyga, with limited published biological data available.
Bellura brehmei
Narrow-leaved Cattail Diver Moth
Bellura brehmei is a North American moth in the family Noctuidae, commonly known as the Narrow-leaved Cattail Diver Moth. It is one of approximately 800 species of Lepidoptera with aquatic or semi-aquatic larvae. Like other members of its genus, the caterpillar likely inhabits wetland environments and feeds on aquatic vegetation, though specific details for this species remain poorly documented.
Bellura gortynoides
White-tailed Diver Moth, white-tailed diver
Bellura gortynoides, commonly known as the white-tailed diver moth, is a North American noctuid moth whose aquatic caterpillars live submerged in freshwater habitats. The larvae feed on aquatic plants, including water lilies, and breathe by periodically surfacing to capture air through specialized spiracles. Adults are strictly nocturnal. The species belongs to the poorly studied group of aquatic moths, which have received limited scientific attention despite their unusual ecology.
Belostoma bakeri
giant water bug
Belostoma bakeri is a giant water bug in the family Belostomatidae, described by Montandon in 1913. The species is distributed across Central America and North America. Research at Montezuma Well, Arizona has established it as a significant top predator in fishless desert spring ecosystems, where it contributes substantially to secondary consumer production and trophic energy flow.
Belostoma confusum
Belostoma confusum is a species of giant water bug in the family Belostomatidae, described by Lauck in 1959. As a member of this family, it is an aquatic predator found in freshwater habitats. The species occurs in North America and Middle America based on distribution records. Like other Belostoma species, it possesses raptorial forelegs adapted for capturing prey and likely exhibits the reversed sexual size dimorphism characteristic of the genus, where females are larger than males and males carry eggs on their backs.
Belostoma minor
giant water bug
Belostoma minor is a species of giant water bug in the family Belostomatidae. It occurs in the northern Caribbean bioregion, with documented records from Cuba, the Dominican Republic, Jamaica, Puerto Rico, the U.S. Virgin Islands, and southern Florida. Like other members of its genus, it is an aquatic predator. The species was described by Palisot de Beauvois in 1820.
Belostoma testaceum
giant water bug
Belostoma testaceum is a species of giant water bug in the family Belostomatidae. It is found in the eastern United States, ranging from New York south to southern Florida and west to Texas and Michigan. Like other members of its family, it is an aquatic predator inhabiting freshwater environments.
Belostomatidae
giant water bugs, toe-biters, Indian toe-biters, electric-light bugs, alligator ticks, alligator fleas
Belostomatidae is a family of large freshwater hemipteran insects comprising approximately 170 species worldwide. Members are the largest insects in the order Hemiptera, with some species exceeding 12 cm in length. They are aggressive predators found in ponds, marshes, and slow-flowing streams, feeding on aquatic invertebrates, fish, amphibians, and even small vertebrates. The family exhibits remarkable paternal care, with males of many species carrying eggs on their backs until hatching. Several species are consumed as food in Southeast Asia.
Belostomatinae
giant water bugs
Belostomatinae is a subfamily of large aquatic true bugs within the family Belostomatidae. Members are commonly known as giant water bugs or toe-biters. They are among the largest insects in the order Hemiptera and are entirely aquatic as adults. The subfamily includes genera such as Belostoma and Appasus, distinguished from the other subfamily Lethocerinae by their smaller adult size and different respiratory strategies.