Stream-insect
Guides
Acentrella nadineae
small minnow mayfly
Acentrella nadineae is a small minnow mayfly in the family Baetidae. The species was described in 2009 and remained known only from nymphs until successful rearing produced the first documented adults. It inhabits cool, clean, swift rocky streams across parts of the eastern and midwestern United States. Near final instar nymphs exhibit unusual madicolous behavior, living in thin water films on rock surfaces.
Agathon comstocki
Comstock's Net-winged Midge
Agathon comstocki is a species of net-winged midge in the family Blephariceridae, described by Kellogg in 1903. The common name honors the American entomologist John Henry Comstock. Net-winged midges in this family are specialized for life in fast-flowing aquatic environments, with larvae adapted to cling to rocks in turbulent water. The species is rarely encountered and poorly documented in scientific literature.
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-emergingmaintainlowhighdissolvedoxygenlevelsthroughoutyearUnitedStatesdistributioncenteredextendssoutheasternmonthstypicallythroughthisactivitygivesrisecommonnamedonotprovidesqualitymonitoringnodirecthabitatmorphologysizegenitalicAllocapnia vivipara
Shortwing Snowfly, short-wing snowfly
Allocapnia vivipara, commonly known as the shortwing snowfly, is a species of small winter stonefly in the family Capniidae. It is native to North America and has been recorded from multiple states in the central United States. The species was originally described as Capnella vivipara by Claassen in 1924 before being transferred to Allocapnia. As a winter stonefly, it belongs to a group adapted to cold-season activity.
Baetis bicaudatus
small minnow mayfly
Baetis bicaudatus is a small minnow mayfly in the family Baetidae, described by Dodds in 1923. It inhabits streams across western North America from Alaska to the southwestern United States and northern Canada. The species is bivoltine, producing two generations annually, with distinct summer and winter generations that differ in size and susceptibility to parasitism. Adults exhibit characteristic mayfly behavior including swarming mating aggregations, while nymphs are important grazers on periphyton in stream ecosystems.
Baetis notos
Baetis notos is a species of small minnow mayfly in the family Baetidae. It is found in Central America and North America, with its North American range extending across southern Mexico, the southern United States, and the northwestern United States. The species was described by Allen and Murvosh in 1987.
Bibiocephala grandis
Bibiocephala grandis is a species of net-winged midge in the family Blephariceridae, a group of specialized aquatic flies. The species was described by Osten Sacken in 1874. Members of Blephariceridae are typically associated with fast-flowing streams and rivers, where larvae attach to rocks in turbulent water.
Blepharicera
net-winged midge
The genus Blepharicera Macquart, 1843 comprises net-winged midges in the family Blephariceridae, with approximately 60 species worldwide and 12 known species in China. It is the most species-rich blepharicerid genus in China, concentrated in Southwest China. The genus is characterized by distinctive wing venation with net-like patterns of folds and transversely divided compound eyes. Recent taxonomic work has expanded knowledge through DNA barcoding and descriptions of new species from China and North America.
Calineuria
common stoneflies
Calineuria is a genus of stoneflies in the family Perlidae, established by Ricker in 1954. The genus contains approximately seven described species distributed across western North America and East Asia. Species such as Calineuria californica have been subjects of life history studies in stream environments. The genus was taxonomically revised from previously broader classifications, with C. californica formerly placed in Acroneuria.
Capnura
small winter stoneflies
Capnura is a genus of small winter stoneflies in the family Capniidae, established by Banks in 1900. The genus contains approximately seven described species distributed primarily in North America. These stoneflies are part of the winter-emerging group of Plecoptera, with adults typically active during cold months when most other insects are inactive.
Cleptelmis addenda
Cleptelmis addenda is a species of riffle beetle in the family Elmidae, first described by Fall in 1907. Riffle beetles are aquatic insects adapted to life in fast-flowing streams and rivers. The species is known from North America, though specific details about its biology remain poorly documented.
Corydalus texanus
Western Dobsonfly
Corydalus texanus is a large megaloopteran insect commonly known as the Western Dobsonfly. Adults are among the largest winged insects in their range, with males distinguished by elongated sickle-shaped mandibles used in combat with rivals. Females possess shorter but powerful jaws capable of delivering a painful bite. The aquatic larval stage, known as hellgrammites, are predaceous and serve as important indicators of stream health. Adults are attracted to lights and may be observed near water bodies at night.
Desmona bethula
amphibious caddisfly
Desmona bethula, commonly known as the amphibious caddisfly, is a species of northern caddisfly in the family Limnephilidae. It is notable for its unusual terrestrial feeding migration behavior, in which fifth-instar larvae leave streams at night to feed on semiaquatic plants before returning to the water. This species is univoltine with autumn emergence and has been proposed as a potential evolutionary link between aquatic and secondarily terrestrial caddisfly lineages.
Diamesa nivoriunda
winter midge, snow midge
Diamesa nivoriunda is a species of non-biting midge in the family Chironomidae. Adults are active during winter months and have been observed walking on snow during warm spells. Like other members of the genus Diamesa, this species does not feed as an adult. The larvae develop in cold, running water where they feed on organic debris. The species belongs to a group commonly referred to as "winter midges" or "snow midges" due to their cold-season activity pattern.
Dolophilodes dorca
Dolophilodes dorca is a species of caddisfly in the family Philopotamidae. Members of this genus are small, slender caddisflies associated with lotic (flowing water) habitats. The larvae construct silken retreats and capture nets for feeding on fine particulate organic matter. Like other philopotamids, adults are typically nocturnal and are attracted to light.
Dubiraphia giulianii
Giuliani's Dubiraphian Riffle Beetle
Dubiraphia giulianii is a species of riffle beetle (family Elmidae) described by Van Dyke in 1949. Like other elmid beetles, it is adapted to life in flowing water environments. The species is known from North America, though detailed biological information remains limited.
Epeorus albertae
flatheaded mayfly
Epeorus albertae is a flatheaded mayfly in the family Heptageniidae, distributed across northern and western North America. Laboratory studies indicate that nymphal growth rate and activity are strongly temperature-dependent, with optimal growth occurring at 15°C compared to slower development at lower temperatures. Nymphs exhibit behavioral thermoregulation by seeking refugia at cold temperatures, suggesting adaptation to thermally variable stream environments.
Ephemerella subvaria
red quill, Dark Hendrickson
Ephemerella subvaria is a spiny crawler mayfly in the family Ephemerellidae. The species was described by McDunnough in 1931. It is widely distributed in the eastern United States with limited occurrence in the upper Midwest. A 2019 record from Ohio represents the first state documentation, with specimens reared from nymphs collected in March to adult emergence in late April.
Eubrianax edwardsii
water penny beetle
Eubrianax edwardsii is a species of water penny beetle in the family Psephenidae, found in North America. Water penny beetles are aquatic insects with flattened, disc-shaped larvae that cling to rocks in streams and rivers. The family Psephenidae is a small group of beetles specialized for life in flowing freshwater habitats.
Glossosomatinae
Glossosomatinae is a subfamily of caddisflies (order Trichoptera) in the family Glossosomatidae. Larvae construct distinctive dome-shaped or tortoise-like portable cases from sand grains and small stones, earning them the common name 'tortoise case makers.' The subfamily is distinguished from the other glossosomatid subfamily, Protoptilinae, primarily by adult genitalic characters and larval case morphology. Members are found in running waters across multiple continents, with larvae serving as important indicators of stream health due to their sensitivity to pollution and habitat disturbance.
Gonielmis
Gonielmis is a genus of riffle beetles (family Elmidae) described by Sanderson in 1954. These beetles are aquatic insects associated with flowing water habitats. The genus belongs to the tribe Elmini within the subfamily Elminae. Taxonomic status varies between sources, with some treating it as a synonym of Heterlimnius while others recognize it as valid.
Hexacylloepus
riffle beetles
Hexacylloepus is a genus of riffle beetles in the family Elmidae, established by Hinton in 1940. The genus contains approximately 19 described species. As with other elmid beetles, members of this genus are associated with aquatic habitats, particularly flowing water systems.
Hydropsychoidea
net-spinning caddisflies
Hydropsychoidea is a superfamily of caddisflies (order Trichoptera) first described by Curtis in 1835. The constituent families, particularly Hydropsychidae, are commonly known as net-spinning caddisflies due to the distinctive capture nets constructed by their larvae. These insects are predominantly aquatic in their immature stages and are among the most frequently observed caddisflies in stream environments worldwide.
Lepidostoma
Lepidostoma is a genus of caddisflies in the family Lepidostomatidae comprising over 150 described species. The genus is notable for the distinctive case-building behavior of its larvae, which construct portable cases from plant materials, primarily leaf panels in later instars. Larvae are detritivores that process allochthonous organic matter in freshwater streams. The genus has a broad geographic distribution including North America, Europe, Asia, and Africa.
Leptophlebia cupida
Early Brown Spinner, Black Quill
Leptophlebia cupida is a pronggilled mayfly species native to North America, commonly known as the early brown spinner or black quill. The species exhibits a univoltine life cycle with egg diapause during summer months. Nymphs develop through approximately 20-34 instars over 10 months, with emergence occurring from late April to mid-May. Adults are short-lived, non-feeding, and mate in swarms near streams.
Lithoseopsis hysteryx
Mystery Caddisfly
Lithoseopsis hysteryx is a species of caddisfly in the family Lepidostomatidae, described by Ross in 1956. The species is known from limited collections in western North America. Adults are small to medium-sized caddisflies with reduced wing venation characteristic of the genus. The larval stage constructs portable cases using mineral particles.
Maccaffertium luteum
Maccaffertium luteum is a species of flat-headed mayfly in the family Heptageniidae, originally described by Clemens in 1913. The genus Maccaffertium was historically treated as a subgenus of Stenonema but was elevated to full generic status based on morphological and phylogenetic studies. Like other members of its family, this species exhibits the characteristic subimago stage—a sexually immature winged form unique to mayflies that requires one final molt to reach reproductive adulthood.
Macrelmis texana
Macrelmis texana is a species of riffle beetle in the family Elmidae, described by Schaeffer in 1911. It belongs to a genus of aquatic beetles adapted to living in fast-flowing water. The species has been recorded from both Central America and North America.
Macronychus glabratus
riffle beetle
Macronychus glabratus is a species of riffle beetle in the family Elmidae, described by Say in 1825. It inhabits lotic freshwater environments, specifically stream riffles in North America. Research has documented its life cycle, growth, survival, and production in streams of northwest Arkansas and southeast Texas.
Marilia
Marilia is a genus of caddisflies in the family Odontoceridae, order Trichoptera. Caddisflies in this family are aquatic insects whose larvae construct protective cases from sand grains and small particles. The genus was established by Mueller in 1880 and is distributed primarily in the Neotropical region, with records from Colombia and other parts of South America.
Metrichia
Metrichia is a genus of microcaddisflies in the family Hydroptilidae, established by Ross in 1938. The genus belongs to the tribe Ochrotrichiini and is distributed across northern South America, with confirmed records from Colombia. As with other hydroptilids, adults are minute with reduced wing venation and larvae construct portable, silken cases.
Neophylax consimilis
Neophylax consimilis is a caddisfly species in the family Uenoidae, first described by Betten in 1934. Its larvae construct protective cases using silk and materials gathered from aquatic environments, with documented instances of exceptionally beautiful cases built from stones of varying colors. The species is found in North America and is part of the Nearctic fauna.
Neophylax oligius
autumn sedge
Neophylax oligius, commonly known as the autumn sedge, is a North American caddisfly species in the family Uenoidae. In southern Ontario, larvae grow from late autumn through spring, with adults emerging in September and October following a summer prepupal diapause. The species occupies stream habitats and exhibits case-building behavior typical of the genus.
Neophylax rickeri
Neophylax rickeri is a caddisfly species in the family Uenoidae, described by Milne in 1935. Larvae construct protective cases using silk and materials gathered from their aquatic environment. The species has been studied in northern California streams, where its life history characteristics have been documented.
Neophylax splendens
Neophylax splendens is a species of caddisfly in the family Uenoidae (formerly Thremmatidae). Larvae construct protective cases using silk and materials gathered from streambeds. The species was first described from North America in 1948 and has since been recorded in the Cypress Hills of Saskatchewan, Canada, representing a significant biogeographical extension linking montane regions of British Columbia and Utah to the southwestern corner of Saskatchewan.
Nerophilus
mortarjoint casemakers
Nerophilus is a monotypic genus of caddisflies in the family Odontoceridae, containing the single described species N. californicus. These insects are commonly known as mortarjoint casemakers, a name reflecting their larval case-building behavior. The genus was established by Nathan Banks in 1899 and is endemic to western North America. As members of the order Trichoptera, adults possess hairy wings and aquatic larval stages.
Nigronia serricornis
Serrate Dark Fishfly, Saw-combed Fishfly, Hellgrammite
Nigronia serricornis is a large aquatic insect in the family Corydalidae, commonly known as the serrate dark fishfly or saw-combed fishfly. The aquatic larvae, often called hellgrammites, are sit-and-wait ambush predators and frequently the largest insect predators in small woodland streams. Adults are short-lived, weak fliers that do not disperse far from their emergence sites. The species has a broad distribution across eastern North America with documented genetic structure shaped by the Appalachian Mountains.
Optioservus heteroclitus
Optioservus heteroclitus is a species of riffle beetle in the family Elmidae, described by White in 1978 as part of a taxonomic revision of Nearctic Optioservus. The species was distinguished based on male genitalia, elytral patterns and shape, and geographic distribution. Like other elmid beetles, it is associated with aquatic environments, specifically flowing water habitats.
Paraleptophlebia guttata
dappled prong-gilled mayfly
Paraleptophlebia guttata is a prong-gilled mayfly in the family Leptophlebiidae. Adults are known from southeastern Canada, northern Canada, and the eastern United States. The species is part of a diverse genus of stream-dwelling mayflies characterized by forked gills on abdominal segments.
Philorus
Philorus is a genus of net-winged midges in the family Blephariceridae, established by Kellogg in 1903. Members of this genus are aquatic flies whose larvae inhabit fast-flowing streams and rivers, where they attach to rocks using specialized sucking discs. The genus is part of a family notable for having some of the most highly specialized larval adaptations among Diptera for life in torrential waters.
Stenelmis cheryl
Cheryl's Riffle Beetle
Stenelmis cheryl, commonly known as Cheryl's riffle beetle, is a species of riffle beetle in the family Elmidae. The species was described by Brown in 1987. Riffle beetles are aquatic insects typically associated with flowing water habitats. Stenelmis cheryl has been documented in Central America and North America based on occurrence records.
Strophopteryx
mottled willowfly (for S. fasciata)
Strophopteryx is a genus of winter stoneflies comprising seven described species. Members are found in the Holarctic region, with records from North America and the Russian Far East. The genus belongs to the family Taeniopterygidae, a group characterized by adult emergence during cold months. Strophopteryx fasciata, the mottled willowfly, is the most well-known species and has been the subject of mitochondrial genome sequencing.
Symbiocladius
Symbiocladius is a genus of non-biting midges (Diptera: Chironomidae) in the subfamily Orthocladiinae. Species in this genus are obligate ectoparasites of mayfly nymphs (Ephemeroptera), attaching to first instar hosts to feed on haemolymph and associated tissues. The genus is known from the Palaearctic region, with records across Central and Eastern Europe. Symbiocladius rhithrogenae is the most studied species, documented to prevent host moulting and potentially cause sterility or death.
Taenionema
winter stoneflies
Taenionema is a genus of winter stoneflies (Plecoptera: Taeniopterygidae) comprising approximately 14 described species. The genus was established by Banks in 1905 with Taenionema analis as the type species. Species are distributed across the Nearctic and eastern Palearctic regions, with 13 species native to North America and one species (T. japonicum) ranging across Japan, Korea, Mongolia, Russia and northeastern China. A second Eastern Hemisphere species, T. sinensis, was described in 2023 from southeastern China.
Tsalia berneri
Tsalia berneri is a species of mayfly in the family Ephemerellidae, originally described as Ephemerella berneri by Allen & Edmunds in 1958. The genus Tsalia was later established to accommodate this and related species based on distinctive morphological features. This Nearctic species is known from limited records in North America. Like other members of Ephemerellidae, it is a small to medium-sized mayfly with aquatic nymphal stages.
Wormaldia arizonensis
Wormaldia arizonensis is a species of caddisfly in the family Philopotamidae, originally described by Ling in 1938. It belongs to the second largest genus in its family, with approximately 175 extant species worldwide. The species is known from the southwestern United States and Mexico. As with other philopotamid caddisflies, it is presumed to have aquatic larval stages and terrestrial adult stages, though specific details of its biology remain poorly documented.