Freshwater
Guides
Procloeon vicinum
Procloeon vicinum is a species of small minnow mayfly in the family Baetidae. It belongs to a genus of mayflies commonly found in freshwater habitats across North America. The species was described by Hagen in 1861 and is currently accepted as valid. Like other members of Baetidae, it likely inhabits running waters and exhibits the typical mayfly life cycle of aquatic nymphal stages followed by short-lived winged adults.
Progomphus
sanddragons
Progomphus is a genus of medium-sized dragonflies in the family Gomphidae, commonly known as sanddragons. The genus is distinguished among Gomphidae by its colored wings, a relatively rare trait in this family. Species are found primarily in tropical regions of the Americas, with adults typically observed near freshwater sandy beaches and pools.
Progomphus bellei
Belle's Sanddragon
Progomphus bellei, commonly known as Belle's Sanddragon, is a species of clubtail dragonfly in the family Gomphidae. It is endemic to the United States. The species inhabits rivers and freshwater lakes.
Protosialis glabella
Protosialis glabella is a species of alderfly in the family Sialidae, order Megaloptera. The genus Protosialis represents one of several genera within Sialidae, a family of aquatic insects whose larvae are predatory and develop in freshwater habitats. Adults are typically nocturnal and short-lived, with reduced mouthparts and a primary focus on reproduction. The species was described by Ross in 1937. Megalopterans as a group are considered primitive holometabolous insects, retaining many ancestral characteristics.
Pseudiron centralis
White Sand-river Mayfly
Pseudiron centralis is a predaceous mayfly species endemic to sandy freshwater river habitats in North America. It exhibits a univoltine summer life cycle with an extended egg stage lasting 9–10 months. Larvae are active epibenthic predators specialized for feeding on psammophilous chironomid larvae, with distinct microhabitat shifts during development: early instars occupy marginal sands, while later instars inhabit shifting sand dunes in main channel areas. The species shows low population density but also low mortality, with random dispersion patterns in mature larvae.
Pseudochironomus
nonbiting midge
Pseudochironomus is a genus of nonbiting midges in the family Chironomidae, containing more than 20 described species distributed across the Americas and Europe. The genus belongs to the tribe Pseudochironomini within subfamily Chironominae. Larvae are aquatic and have been studied for their growth responses to diet quality and thermal conditions.
Pseudochironomus richardsoni
A non-biting midge species in the family Chironomidae, first described by Malloch in 1915. Laboratory studies demonstrate strong phenotypic plasticity in growth and development in response to food quality and thermal conditions. The species exhibits compensatory growth capacity, maintaining development rates under thermal stress when high-quality food is available.
Psilotreta
mortarjoint casemakers
Psilotreta is a genus of caddisflies in the family Odontoceridae, commonly known as mortarjoint casemakers. The genus contains more than 30 described species. These insects are aquatic in their larval stage and are found in freshwater habitats. Adults are terrestrial and short-lived.
Psychoglypha bella
Beautiful Northern Caddisfly
Psychoglypha bella is a species of caddisfly in the family Limnephilidae, commonly known as the Beautiful Northern Caddisfly. Originally described as Glyphotaelius bellus by Banks in 1903, this species is part of the tribe Chilostigmini within the subfamily Limnephilinae. The genus Psychoglypha comprises northern caddisflies found primarily in North American freshwater habitats.
Psychomyiidae
Net Tube Caddisflies, tube-making caddisflies, trumpet-net caddisflies
Psychomyiidae is a family of tube-making caddisflies (order Trichoptera) characterized by larvae that construct silken galleries or tubes on submerged surfaces. Adults are typically small with reduced wing venation, including absence of forewing fork I and shortened hindwing forks. The family is distinguished from similar Polycentropodidae by leg spur formula 2-4-4, short thyridial cell, and male genitalia with elongate preanal appendages and reduced tergum IX. Larvae possess separated submental sclerites, broad foretrochantin, and whip-like pupal mandible apices. The family contains approximately 10 extant genera and has a global distribution with notable diversity in the Oriental and Western Palearctic regions.
Psychomyioidea
net-tube caddisflies
Psychomyioidea is a superfamily of caddisflies (Trichoptera) in the suborder Annulipalpia, commonly known as net-tube caddisflies. The superfamily comprises five families: Psychomyiidae, Xiphocentronidae, Dipseudopsidae, Polycentropodidae, and Pseudoneureclipsidae. Members are characterized by specialized antennal sensilla and larval case-building behavior using silk nets or tubes. The group is primarily distributed in tropical and subtropical regions worldwide, with significant diversity in the Neotropics, Oriental region, and Brazilian Amazon.
Ptilostomis
Giant Rusty Sedges, Giant Casemakers
Ptilostomis is a genus of large caddisflies commonly known as giant casemakers or giant rusty sedges. The genus comprises at least four described species distributed in North America. Adults are recognized by their substantial size relative to other caddisflies and rusty or brownish coloration. Larvae construct portable cases using plant material, characteristic of the family Phryganeidae.
Ptilostomis postica
giant casemaker
Ptilostomis postica is a species of giant casemaker caddisfly in the family Phryganeidae. It is found in North America. The species was originally described as Neuronia postica by Walker in 1852. As a member of Phryganeidae, it belongs to a family of relatively large caddisflies known for constructing portable cases from plant material.
Ptychoptera
phantom crane flies
Ptychoptera is a genus of phantom crane flies comprising at least 70 described species. The genus is characterized by larvae that are aquatic or semi-aquatic detritivores inhabiting freshwater environments. Adults are recognized by their distinctive wing folding behavior, giving rise to the common name "fold-winged crane flies." Species occur across the Holarctic and Oriental regions, with significant diversity in China.
Pycnopsyche gentilis
caddisfly
Pycnopsyche gentilis is a northern caddisfly in the family Limnephilidae. Larvae are shredders that inhabit allochthonous organic materials in freshwater streams, where they feed on leaf litter colonized by aquatic fungi. The species is contemporaneous with congeneric P. luculenta, though larvae differ in case materials and habitat preferences. Adult males exhibit temporal partitioning of flight activity, with distinct peak arrival times at light sources when active on the same night as congeners.
Ramellogammarus
Stumptown scud (R. similimanus)
Ramellogammarus is a genus of freshwater amphipod crustaceans in the family Anisogammaridae, established by Bousfield in 1979. The genus includes species with highly restricted geographic distributions in the Pacific Northwest of North America. R. similimanus, known as the Stumptown scud, is endemic to the Portland metropolitan area of Oregon, while R. vancouverensis occurs in British Columbia.
Ramphocorixa
Ramphocorixa is a genus of water boatmen (Corixidae) established by Abbott in 1912, containing at least two described species. The genus includes a notable marine species, R. balanodis, which exhibits extreme morphological adaptations for feeding on barnacles in saltwater intertidal habitats—unusual for a family predominantly found in freshwater. Most species occur in freshwater lakes and ponds across North, Central, and northern South America.
Ranatra
water stick-insect, water scorpion, water mantis
Ranatra is a genus of slender aquatic predatory insects in the family Nepidae, commonly called water stick-insects or water scorpions. The genus contains over 140 species distributed across freshwater habitats worldwide, with highest diversity in South America and Asia. These insects are sit-and-wait predators that use raptorial forelegs to capture prey. They possess a distinctive long caudal siphon for breathing while submerged.
Ranatra brevicollis
Western Waterscorpion
Ranatra brevicollis is a species of waterscorpion in the family Nepidae, first described by Montandon in 1910. It is distributed across Central America and North America. The species belongs to a genus of aquatic predatory insects commonly known as waterscorpions due to their elongated, scorpion-like appearance. It is recognized by the common name Western Waterscorpion.
Ranatra fusca
brown water scorpion, brown waterscorpion
Ranatra fusca is a predatory aquatic bug in the family Nepidae, commonly called the brown water scorpion. Native to North America, it inhabits freshwater environments where it hunts small invertebrates using raptorial forelegs. Adults reach 3.2–4.2 cm in length and possess a long respiratory siphon for breathing at the water surface. The species is most active from spring through autumn.
Ranatra quadridentata
waterscorpion
Ranatra quadridentata is a species of waterscorpion described by Stål in 1862. As a member of the family Nepidae, it is an aquatic predatory insect that inhabits freshwater environments. The species has been documented in Central America and North America, with 188 observations recorded on iNaturalist.
Rhagovelia distincta
smaller water strider
Rhagovelia distincta is a species of smaller water strider in the family Veliidae. It inhabits freshwater surface habitats across Central America and North America. As a member of the genus Rhagovelia, it belongs to a group of semi-aquatic true bugs adapted for life on the water surface.
Rhantus
Rhantus is a genus of predaceous diving beetles (Dytiscidae) comprising approximately 100 species with worldwide distribution. Members of this genus are primarily associated with lentic freshwater habitats, particularly pools and marshy wetlands. The genus is currently recognized as paraphyletic; taxonomic revision is anticipated following 2017 research that transferred 17 species to newly established genera (Nartus, Meridiorhantus, Caperhantus, and Carabdytes). Several species have independently colonized oceanic islands and undergone endemic diversification.
Rhantus suturellus
Rhantus suturellus 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 is part of a genus of aquatic beetles adapted to freshwater environments.
Rhantus wallisi
Rhantus wallisi is a predaceous diving beetle in the family Dytiscidae, described by Hatch in 1953. The species is endemic to North America, with documented occurrences in western Canada including Alberta and British Columbia. Like other members of the genus Rhantus, it is an aquatic predator inhabiting freshwater environments.
Rheumatobates hungerfordi
Rheumatobates hungerfordi is a species of water strider in the family Gerridae, first described by Wiley in 1923. It belongs to the subfamily Rhagodotarsinae, a group characterized by specialized adaptations for life on the water surface. The genus Rheumatobates is distinguished by modified leg structures, particularly in males, used in mating displays and locomotion on water. This species occurs in freshwater habitats across parts of North and Middle America.
Rhyacophila acutiloba
Rhyacophila acutiloba is a species of free-living caddisfly in the family Rhyacophilidae, first described by Morse & Ross in 1971. As a member of the genus Rhyacophila, it belongs to a group commonly known as "caseless caddis" or "free-living caddisflies" whose larvae do not construct portable cases. The species is known from North America, with records from Vermont and other parts of the Nearctic region. Like other rhyacophilids, it is associated with lotic (flowing water) habitats.
Saetheria
Saetheria is a genus of non-biting midges in the family Chironomidae, established by Jackson in 1977. It belongs to the subfamily Chironominae and is distributed across the Nearctic and Palaearctic regions, including Europe and the Russian Far East. The genus comprises at least four described species. Taxonomic revisions have provided detailed morphological descriptions of adult males, pupae, and larvae for multiple species.
Saldoida
Saldoida is a genus of shore bugs in the family Saldidae, established by Osborn in 1901. The genus comprises five described species distributed across Asia and Australia. At least one species, S. armata, exhibits distinctive ant-mimicry morphology with thoracic horns. Members inhabit damp areas adjacent to freshwater sources.
Salmincola
Salmincola is a genus of freshwater parasitic copepods in the family Lernaeopodidae. These ectoparasites are common on salmonid fishes throughout the Northern Hemisphere. The genus exhibits substantial geographic variation in infection rates across water bodies, and current taxonomic definitions based on decades-old morphological descriptions may obscure cryptic diversity. Species in this genus are considered pests by fisheries management agencies due to their impact on host fish populations.
Salmoperla sylvanica
Salmoperla sylvanica is a species of stonefly in the family Perlodidae, described in 1987 from California. It belongs to the tribe Arcynopterygini within the subfamily Perlodinae. Like other perlodid stoneflies, it is associated with freshwater habitats. The species is known from very few records, with only two observations documented on iNaturalist.
Sanfilippodytes compertus
Cool Predaceous Diving Beetle
Sanfilippodytes compertus is a species of predaceous diving beetle in the family Dytiscidae. It is known from western North America, with confirmed records in Alberta and British Columbia, Canada. The species was described by Brown in 1932. Like other members of the genus, it is likely associated with freshwater habitats.
Sanfilippodytes edwardsi
Sanfilippodytes edwardsi is a predaceous diving beetle in the family Dytiscidae, first described by Wallis in 1933. The species is endemic to western North America, with records from Alberta and British Columbia in Canada. As a member of the subfamily Hydroporinae, it inhabits freshwater aquatic environments where it preys on small invertebrates.
Sciomyzini
snail-killing flies
Sciomyzini is a tribe of snail-killing flies within the family Sciomyzidae. Larvae are specialized predators and parasitoids of freshwater nonoperculate pulmonate snails. The tribe exhibits variable degrees of specialization: some species are highly specialized parasitoids with eggs laid directly on snail shells and puparia modified to fit tightly within host shells, while others are less specialized with eggs laid on vegetation and larvae acting as parasitoid-predator-saprophages. The tribe includes at least 13 genera and has been documented in both Palearctic and Nearctic regions.
Sepedon fuscipennis
marsh fly
Sepedon fuscipennis is a species of marsh fly in the family Sciomyzidae. The larvae are aquatic predators of pulmonate snails, living just beneath the water surface suspended by water-resistant hairs surrounding their posterior spiracles. Adults are slender flies with a concave face and jutting antennae; males have distinctive bowed hind tibiae and swollen, toothed hind femora for grasping females during mating. The species exhibits overlapping generations during summer with unimodal population peaks, and has been studied for its potential in biological control of snail hosts of parasitic diseases.
Sericostomatidae
Bushtailed Caddisflies
Sericostomatidae is a family of caddisflies (Trichoptera) commonly known as bushtailed caddisflies. The family comprises approximately 19 genera and at least 90 described species. Larvae construct portable cases using silk and environmental materials. The family has a global distribution with notable diversity in the Palearctic region, including endemic species in the Balkans, Iberian Peninsula, and Madagascar.
Sericostomatoidea
Sericostomatoidea is a superfamily of caddisflies (Trichoptera) containing approximately 13 families. The superfamily includes diverse case-making caddisflies, notably the Helicopsychidae (snail-case caddisflies) and the Australasian endemic family Conoesucidae. Molecular and morphological studies have confirmed the monophyly of at least some constituent families, though relationships among families remain under investigation.
Setodes
long-horned caddisfly
Setodes is a genus of long-horned caddisflies in the family Leptoceridae, established by Rambur in 1842. The genus contains at least 230 described species, making it one of the largest genera within the family. Species occur across multiple continents including Africa, Asia, and Madagascar, with colonization patterns suggesting potential dispersal from India to Madagascar. Larval stages are aquatic and inhabit freshwater lotic environments.
Sialis rotunda
Alderfly
Sialis rotunda is a species of alderfly in the family Sialidae, order Megaloptera. It is a small to medium-sized aquatic insect whose larvae develop in freshwater habitats. Adults are short-lived and primarily focus on reproduction. The species was described by Nathan Banks in 1920 and is native to western North America.
Sigara bradleyi
Sigara bradleyi is a species of water boatman in the family Corixidae, first described by Abbott in 1913. As a member of the genus Sigara, it belongs to a diverse group of aquatic insects commonly found in freshwater habitats. The species is known to occur in North America and the Caribbean, though detailed biological information remains limited. Like other corixids, it likely inhabits ponds, lakes, and slow-moving waters where it occupies the benthic zone.
Sigara hubbelli
Sigara hubbelli is a species of water boatman in the family Corixidae, described by Hungerford in 1928. It belongs to the genus Sigara, a diverse group of aquatic true bugs found in freshwater habitats. The species is documented from North America, though detailed ecological and biological information remains limited in available sources.
Sigara hydatotrephes
Sigara hydatotrephes is a species of water boatman in the family Corixidae. It belongs to the large genus Sigara, which contains numerous species of aquatic insects found in freshwater habitats. The species was described by Kirkaldy in 1908. Like other corixids, it is adapted to life in water with modified hind legs for swimming.
Sigara lineata
Sigara lineata is a species of water boatman in the family Corixidae. It is found in North America. Water boatmen are aquatic insects that inhabit freshwater environments.
Sigara mississippiensis
Sigara mississippiensis is a species of water boatman in the family Corixidae, described by Hungerford in 1942. As a member of the genus Sigara, it belongs to a diverse group of aquatic true bugs commonly found in freshwater habitats across North America. The species is poorly documented in public scientific literature, with minimal observational records available.
Sigara omani
Sigara omani is a species of water boatman in the family Corixidae, first described by Hungerford in 1930. Despite its specific epithet suggesting a connection to Oman, the species is native to North America. Water boatmen in this genus are aquatic insects that inhabit freshwater environments. Available information about this particular species is limited.
Sigara ornata
ornate water boatman
Sigara ornata is a species of water boatman (family Corixidae) found in North America. Water boatmen are aquatic true bugs that inhabit freshwater environments, where they are known for their oar-like hind legs adapted for swimming. The specific epithet "ornata" suggests distinctive patterning or markings, though detailed morphological descriptions for this species are limited in available sources.
Sigara sigmoidea
Sigara sigmoidea is a species of water boatman in the family Corixidae, described by Abbott in 1913. The species name 'sigmoidea' refers to an S-shaped or sigma-like characteristic, likely of the male genitalia or abdominal structure, a common naming convention in this genus. Like other Corixidae, it is an aquatic insect inhabiting freshwater environments. The genus Sigara is one of the most species-rich genera of water boatmen in the Northern Hemisphere.
Sigara trilineata
Sigara trilineata is a species of water boatman in the family Corixidae, found in North America. Water boatmen are aquatic insects that inhabit freshwater environments. The species name "trilineata" refers to three lines, likely describing a distinctive marking pattern on the body. As a member of the Corixidae, it possesses the family's characteristic oar-like hind legs adapted for swimming.
Simocephalus
water flea
Simocephalus is a genus of freshwater cladoceran crustaceans commonly known as water fleas. Members exhibit the characteristic cladoceran life cycle with alternating parthenogenetic and sexual reproduction phases. The genus has been studied extensively for reproductive biology, with environmental factors such as temperature, food concentration, crowding, and illumination influencing life history traits.
Simocephalus serrulatus
Simocephalus serrulatus is a freshwater cladoceran crustacean in the family Daphniidae. It is a cosmopolitan zooplankton species found across multiple continents including Australasian, Afrotropical, Nearctic, and Neotropical regions. The species has been used in ecotoxicological studies, particularly research on per- and polyfluoroalkyl substances (PFAS) tolerance and population-level variation in life history traits.