Lotic
Guides
Agapetus
Agapetus caddisflies
Agapetus is a genus of caddisflies in the family Glossosomatidae, commonly known as saddle-case makers. Larvae construct portable, dome-shaped cases from sand grains and are found in lotic freshwater habitats. The genus has a global distribution with species documented across Europe, Asia, Australia, and North America. Life cycles vary among species, ranging from univoltine to trivoltine patterns depending on geographic location and environmental conditions.
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-emergingmaintainlowhighdissolvedoxygenlevelsthroughoutyearUnitedStatesdistributioncenteredextendssoutheasternmonthstypicallythroughthisactivitygivesrisecommonnamedonotprovidesqualitymonitoringnodirecthabitatmorphologysizegenitalicAlloperla
Alloperla is a genus of stoneflies in the family Chloroperlidae. Species within this genus inhabit running water environments, including the hyporheic zones of gravel-bed rivers. Some species exhibit extended larval development periods and specialized feeding habits. The genus has a broad distribution across the Holarctic region.
Ambrysus
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).
Ameletidae
combmouthed minnow mayflies
Ameletidae is a family of mayflies commonly known as combmouthed minnow mayflies. The family includes the speciose genus Ameletus, which reaches its greatest diversity in southwestern North America with up to 12 species co-occurring at single sites. The genus Metreletus has a trans-Palaearctic distribution with three recognized species. Ameletidae larvae are aquatic and occur in lotic habitats from small headwater streams to larger rivers.
Amphiagrion abbreviatum
Western Red Damsel
Amphiagrion abbreviatum, the western red damsel, is a narrow-winged damselfly in the family Coenagrionidae. It exhibits unusual habitat plasticity, occurring in both lentic and lotic freshwater systems. The species shows distinct perching and roosting behaviors that differ from sympatric congeners. It is widely distributed across western North America with stable populations.
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.
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.
Ancyronyx variegata
Spider Water Beetle
Ancyronyx variegata is a riffle beetle (Elmidae) commonly known as a Spider Water Beetle, characterized by extremely long legs and often a cross-like elytral color pattern that gives it a spider-like appearance. It inhabits clean, pristine running waters in lotic environments and has been studied for its life history and energetics in Northwest Arkansas and Southeast Texas. The species exhibits a univoltine life cycle with adults present year-round.
Anisocentropus
Anisocentropus is a cosmopolitan genus of caddisflies (Trichoptera: Calamoceratidae) comprising over 60 described species distributed across Oriental, Australasian, Afrotropical, Neotropical, Nearctic, and East Palearctic regions. Larvae are case-building detritivores that construct portable shelters from leaf pieces or wood fragments, inhabiting both lotic and lentic freshwater environments depending on species. The genus exhibits notable variation in habitat preference, with some species strictly adapted to standing water while others occupy running water or both environments.
Arctopsyche
Great Gray Spotted Sedges
Arctopsyche is a genus of netspinning caddisflies in the family Hydropsychidae, comprising more than 20 described species. Larvae construct and maintain capture nets throughout the year to filter food from flowing water. The genus exhibits life cycle flexibility, with documented univoltine and semivoltine patterns depending on environmental conditions. Species occur in lotic habitats across the Holarctic region.
Arthroplea bipunctata
flatheaded mayfly
Arthroplea bipunctata is a species of flatheaded mayfly in the family Heptageniidae (sometimes historically placed in Arthropleidae). It is known from North America, with records from the Nearctic region. The species was described by McDunnough in 1924, originally as Cinygma bipunctata. Like other flatheaded mayflies, it belongs to a group adapted to clinging in fast-flowing waters.
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.
Baetisca berneri
Baetisca berneri is an armored mayfly species described from West Virginia streams. The species has been the subject of ecological life history research examining nymphal development and emergence patterns. It belongs to a genus characterized by distinctive armored nymphal forms adapted to lotic environments.
Bibiocephala
net-winged midges
Bibiocephala is a genus of net-winged midges in the family Blephariceridae, established by Osten Sacken in 1874. The genus contains five described species distributed across the Holarctic region. These midges are members of a specialized family whose larvae inhabit fast-flowing streams and rivers. Adult Bibiocephala are characterized by their distinctive wing venation with dense, net-like crossveins that give the family its common name.
Blephariceridae
Net-winged Midges
Blephariceridae, or net-winged midges, are a family of nematoceran flies distinguished by wings with a distinctive network of fissures and folds resembling cracked glass. Adults superficially resemble crane flies but differ in wing shape, head structure, and leg posture. Larvae are specialized inhabitants of torrential streams, possessing six ventral suckers that enable attachment to rocks in flows exceeding 2 m/s. The family contains over 200 species across dozens of genera worldwide, with highest diversity in mountainous regions. Larvae are ecologically significant as diatom grazers in lotic ecosystems.
Boreoheptagyia
Boreoheptagyia is a genus of non-biting midges in the subfamily Diamesinae of the family Chironomidae. The genus was established by Brundin in 1966 and currently comprises approximately 19 described species distributed across the Holarctic region, with particular concentration in mountainous areas of Europe and Asia. Species in this genus are associated with cold, well-oxygenated lotic habitats and exhibit limited dispersal capacity, resulting in restricted, often isolated geographic ranges.
Boyeria vinosa
fawn darner
Boyeria vinosa, the fawn darner, is a dragonfly species in the family Aeshnidae. It inhabits rivers and streams in eastern North America, from southeastern Canada through the eastern United States. Adults are crepuscular, being most active at dusk. The species has a univoltine life cycle with egg diapause and approximately 10 months of larval development.
Brychius hornii
Horn's Crawling Water Beetle
Brychius hornii is a species of crawling water beetle in the family Haliplidae, first described by George Robert Crotch in 1873. It is native to western North America, where adults inhabit small streams and irrigation ditches, primarily on gravel substrates. The species belongs to a small genus of aquatic beetles adapted to life in running water environments.
Camelobaetidius
minnow mayflies
Camelobaetidius is a genus of small minnow mayflies in the family Baetidae, comprising at least 40 described species distributed across the Nearctic and Neotropical regions. The genus is one of the most studied within Baetidae, with nymphs commonly inhabiting lotic (flowing water) environments. Species are distinguished by specific morphological characters, particularly the spatulate (flattened, spoon-shaped) tarsal claws present in nymphs. The genus exhibits considerable diversity in Central and North America, with additional species described from Costa Rica and southeastern Brazil.
Ceraclea enodis
Ceraclea enodis is a species of caddisfly in the family Leptoceridae. Members of this genus are characterized by elongated, slender bodies and long antennae. The species is part of a diverse group of aquatic insects whose larvae construct protective cases from environmental materials.
Cheumatopsyche ela
Cheumatopsyche ela is a species of net-spinning caddisfly in the family Hydropsychidae, first described by Denning in 1942. The species occurs in North America and is part of a genus known for constructing silk capture nets in flowing water habitats. Larvae exhibit density-dependent dispersion patterns in laboratory settings, with aggressive behavior and cannibalism observed at high population densities. As with other hydropsychids, adults are short-lived and primarily focused on reproduction.
Chimarra
Little Black Caddisflies
Chimarra is a large genus of caddisflies (Trichoptera: Philopotamidae) containing more than 630 described species. Adults are commonly known as "little black caddisflies" due to their characteristic dark coloration. The genus has undergone extensive radiation, with species distributed across multiple continents including North America, South America, Europe, Africa, and Asia. Molecular studies have investigated the evolutionary history and biogeographic patterns of diversification within this genus.
Claassenia sabulosa
Shortwing Stonefly, short-wing stone
Claassenia sabulosa, commonly known as the shortwing stonefly, is a species of common stonefly in the family Perlidae. It is found in North America, with documented populations in the western United States including Colorado, as well as Canada. The species has been studied for its life cycle dynamics in Colorado streams and its adult mate-finding behaviors.
Clarkhydrus
Clarkhydrus is a genus of diving beetles in the family Dytiscidae, established in 2018 by Fery & Ribera. The genus was erected to accommodate species previously placed in related genera within the subtribe Deronectina. As a member of the subfamily Hydroporinae, these beetles are small to medium-sized aquatic predators. The genus is relatively recently described, and research on its species-level diversity and ecology is ongoing.
Cleptelmis
Cleptelmis is a genus of riffle beetles in the family Elmidae, established by Sanderson in 1954. The genus contains at least two described species: Cleptelmis addenda and Cleptelmis ornata. Riffle beetles in this family are aquatic insects associated with flowing water habitats.
Clinocerinae
aquatic dance flies
Clinocerinae is a subfamily of dance flies (Empididae) comprising 16 recognized genera including Clinocera, Wiedemannia, Dolichocephala, Trichoclinocera, and Kowarzia. Members are commonly known as aquatic dance flies due to their strong association with freshwater habitats. The subfamily has a global distribution with particularly diverse faunas in the Palaearctic and Oriental regions. Multiple generic revisions and species-level revisions have been published for Nearctic, Palaearctic, and Oriental faunas.
Copelatinae
copelatine diving beetles
Copelatinae is a subfamily of predaceous diving beetles (Dytiscidae) comprising seven genera: Agaporomorphus, Aglymbus, Copelatus, Exocelina, Lacconectus, Liopterus, and Madaglymbus. The genus Copelatus is the largest with approximately 470 described species worldwide, showing greatest diversity in tropical South America, Africa, and Southeast Asia. Members are predominantly aquatic, though some species have colonized highly ephemeral habitats including forest floor depressions. The subfamily exhibits remarkable morphological diversity and includes phylogenetically isolated lineages such as the South African genus Capelatus.
Coptotomus loticus
Coptotomus loticus is a predaceous diving beetle described by Hilsenhoff in 1980. It belongs to the subfamily Coptotominae within Dytiscidae, a family of aquatic beetles. The species is known from eastern Canada, with records from Ontario and Québec. As a member of Coptotomus, it represents one of the less commonly encountered genera in North American dytiscid fauna.
Cordulegastridae
Spiketails, biddie, flying adder
Cordulegastridae, commonly known as spiketails, is a family of dragonflies (Anisoptera) distributed across the Holarctic region. The family contains approximately 51 species in three to four genera, including Cordulegaster, Anotogaster, Neallogaster, and the recently restored Thecagaster and Zoraena. Adults are characterized by large black or brown bodies with yellow markings, blue-green eyes that meet at a single point, and a slow flight pattern 30–70 cm above water. Nymphs are specialized ambush predators that conceal themselves in sand or silt substrates of clean, flowing streams.
Crangonyx gracilis
Northern Lake Crangonyctid
Crangonyx gracilis is a small freshwater amphipod in the family Crangonyctidae, commonly known as the northern lake crangonyctid. It inhabits diverse aquatic environments across North America, including flowing water, standing water, and temporary habitats. The species was described by S.I. Smith in 1871.
Cylloepus
riffle beetles
Cylloepus is a genus of riffle beetles in the family Elmidae, first described by Erichson in 1847. The genus contains approximately six described species distributed across the Americas. Members are aquatic beetles associated with flowing water habitats. Species have been documented from North America, the Caribbean, and South America.
Dicosmoecus atripes
northern caddisfly
Dicosmoecus atripes is a limnephilid caddisfly native to North America. The species has been documented in Rocky Mountain streams of Alberta, Canada, where it exhibits a two-year life cycle with distinct seasonal emergence and larval diapause. Larval microhabitat and dietary preferences shift between early and late instars.
Diura
Diura is a genus of stoneflies (Plecoptera) in the family Perlodidae, comprising approximately seven described species distributed across Europe and North America. Species such as Diura nanseni are univoltine, completing their life cycle in one year with nymphal growth primarily during spring months. Nymphs are typically associated with lotic environments and exhibit predatory or grazing feeding habits depending on species.
Dixella californica
Dixella californica is a species of meniscus midge in the family Dixidae (Order: Diptera). These small, delicate flies are associated with aquatic habitats where their larvae develop. The species was described by Johannsen in 1923 and is known from California. Dixidae larvae are recognized by their distinctive habit of hanging upside down from the water surface film, feeding on microorganisms and organic matter.
Drunella coloradensis
Small Western Green Drake
Drunella coloradensis is a species of spiny crawler mayfly in the family Ephemerellidae, commonly known to anglers as the Small Western Green Drake. The species is found in freshwater streams across western North America, with a range extending from Alaska and northern Canada through the western United States to northern Mexico and Central America. Nymphs are known to alter their behavior in response to short-term pH reductions, becoming more active under acidic conditions. The species is of particular importance to fly fishermen, who imitate its various life stages with artificial flies.
Dubiraphia harleyi
Dubiraphia harleyi is a species of riffle beetle in the family Elmidae, described by Barr in 1984. Riffle beetles are aquatic beetles that inhabit flowing water environments. The species is known from North America.
Elmidae
Riffle beetles
Elmidae, commonly known as riffle beetles, is a family of aquatic beetles in the superfamily Byrrhoidea containing over 150 genera and 1,500 described species. Both adults and larvae are primarily aquatic, inhabiting fast-flowing shallow areas of streams and rivers such as riffles. Adults breathe underwater using a plastron—a microfilm of air held by microscopic hairs on their body surface that enables oxygen diffusion from the water. The family has significant value in freshwater biomonitoring due to their sensitivity to water pollution.
Elmini
riffle beetles
Elmini is a tribe of riffle beetles within the family Elmidae, comprising over 90 genera and approximately 1,200 described species in North America. These beetles are strictly aquatic as adults and larvae, inhabiting flowing water systems. The tribe represents a major radiation within the Elmidae, with species diversity concentrated in freshwater habitats.
Epeorus
Epeorus is a genus of mayflies in the family Heptageniidae. The genus contains multiple subgenera including Caucasiron and Siniron, with species distributed across the Palearctic and Nearctic regions. Larvae are primarily lotic, inhabiting running waters where many species serve as bioindicators for water quality assessments. Several species are dominant components of macroinvertebrate assemblages in upper and midstream river areas.
Ephemerella
Hendricksons, Sulphurs, Pale Duns
Ephemerella is a genus of spiny crawler mayflies comprising approximately 19 described species. Nymphs are characterized by their distinctive defensive posture, curling the abdomen upward in a scorpion-like manner when disturbed. The genus has a widespread distribution across North America and Europe, with species occupying diverse lotic freshwater habitats. Several species, including E. subvaria and E. ignita, have been subjects of detailed life history studies.
Ephemerellidae
Spiny Crawler Mayflies
Ephemerellidae, commonly known as spiny crawler mayflies, is a family of mayflies (Ephemeroptera) comprising approximately 90 species across 8-14 genera. The family is distributed throughout North America and the UK, with additional records from Europe and Asia. Nymphs inhabit lotic-erosional environments including flowing streams of all sizes, lake shores, and beaches with wave action. They are primarily collector-gatherers and serve as important indicators of water quality due to their sensitivity to pollution.
Eubriinae
Eubriinae is a cosmopolitan subfamily of water penny beetles (Psephenidae) comprising approximately 15 genera and 144 species, with greatest diversity in Asia. Adults are distinguished by a convex dorsal body form, truncate or emarginate anterior pronotum with exposed head, non-tapering maxillary palpus apex, and five abdominal ventrites. Larvae are aquatic and exhibit a metapneustic respiratory system with spiracles positioned near the bases of paratergites VIII. The subfamily exhibits nearly worldwide distribution except Antarctica and some oceanic islands including New Zealand.
Gammarus pseudolimnaeus
Northern Spring Amphipod
Gammarus pseudolimnaeus is a freshwater amphipod crustacean inhabiting lotic (flowing water) environments in North America. The species exhibits complex behavioral ecology, including size-selective predation vulnerability to fish predators such as brook trout and sculpins, and chemically-mediated responses to predation risk that influence reproductive behavior. Population dynamics are characterized by univoltine (single annual) generation cycles with high mortality during early life stages and winter periods. The species serves as an important prey item in stream food webs and has been extensively studied as a model organism for freshwater invertebrate ecology, toxicology, and predator-prey interactions.
freshwaterloticamphipodpredator-preybehavioral-ecologytoxicologyunivoltineNorth-Americamodel-organismstream-ecologysize-selective-predationchemical-ecologyparasitismacanthocephalacopper-toxicitymate-guardingcalceolimicrohabitat-selectionthigmotaxisdiel-activityseasonal-dynamicsproduction-ecologydriftbrook-troutsculpinOntarioVirginiaGammaridaecrustaceaninvertebratesenticaudataBousfield-1958Northern-Spring-AmphipodGlossosoma
little black caddisflies
Glossosoma is a genus of small caddisflies comprising over 110 described species, commonly known as little black caddisflies. Larvae construct portable dome-shaped cases from mineral particles and occupy the upper surfaces of stones in flowing waters. The genus exhibits multivoltine life histories with varying generation times among species.
Goeridae
Armour-ballast Caddisflies
Goeridae is a family of caddisflies (Trichoptera) comprising approximately 12 genera and at least 160 described species. Larvae are primarily lotic, inhabiting streams and rivers, with some species occupying madicolous habitats such as wet cliff faces. The family is distinguished by larval case construction incorporating ballast stones for weight and stability. Adults exhibit highly modified male genitalia and maxillary palps in some species. Goeridae has a Holarctic distribution with records from North America, Europe, and Asia.
Greniera
Greniera is a genus of black flies in the family Simuliidae, established by Doby and David in 1959. The genus belongs to the tribe Prosimuliini and includes at least two described species: Greniera abdita and Greniera abditoides. Species are known from Europe and North America.
Hemerodromia
dance flies
Hemerodromia is a genus of dance flies (family Empididae) comprising at least 170 described species. Species are primarily associated with lotic freshwater habitats, particularly streams and rivers. Several species show obligate associations with calcareous water systems and tufa formations in limestone karst regions. The genus exhibits high diversity in tropical Southeast Asia, with significant undescribed species richness anticipated.
Heptagenia adaequata
Heptagenia adaequata is a species of flatheaded mayfly in the family Heptageniidae. Described by James Halliday McDunnough in 1924, it is a Nearctic species found in North America. Like other members of its genus, it is associated with running water habitats. The species is represented by relatively few observations in biodiversity databases.
Heptagenia marginalis
Margined Flat-headed Mayfly
Heptagenia marginalis is a species of flatheaded mayfly in the family Heptageniidae, first described by Banks in 1910. It belongs to a family characterized by dorsoventrally flattened body forms adapted to clinging in fast-flowing water. The species is known from North America, though detailed biological information remains limited in available literature.