Stream-insects
Guides
Acentrella
small minnow mayflies
Acentrella is a genus of small minnow mayflies in the family Baetidae. The genus contains at least 26 species distributed across Europe, North America, Asia, and Africa. Nymphs of at least some species inhabit cool, clean, swift rocky streams. Adult stages of several species remain undescribed due to the difficulty of rearing nymphs to maturity.
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.
Arcynopterygini
springflies
Arcynopterygini is a tribe of springflies (Plecoptera) within the family Perlodidae. The tribe contains approximately 11 genera and more than 30 described species. Members are distributed across the Northern Hemisphere, with genera found in North America, Europe, and Asia. The tribe was established by Ricker & Scudder in 1975.
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.
Baetiscidae
armored mayflies
Baetiscidae is a family of mayflies distinguished by their heavily armored nymphs bearing a robust, spiked thoracic notal shield that extends over part of the abdomen. The family contains a single extant genus, Baetisca, with approximately 12 species endemic to North America. Three extinct genera (Protobaetisca, Balticobaetisca, Koonwarrabaetisca) are known from Cretaceous and Eocene deposits, indicating a Pangean origin for the family by at least the Early Jurassic. Together with Prosopistomatidae, Baetiscidae forms the clade Carapacea, characterized by specialized larval armor.
Carapacea
Carapacea is a suborder of mayflies (Ephemeroptera) characterized by nymphs possessing a distinctive carapace-like structure formed from expanded and fused thoracic tergites. This morphological adaptation distinguishes them from other mayfly suborders. The group includes families such as Baetiscidae and Prosopistomatidae. Carapacean mayflies are primarily found in running water habitats.
Heptagenia
flatheaded mayflies
Heptagenia is a genus of flatheaded mayflies in the family Heptageniidae, containing at least 20 described species. Nymphs are primarily benthic inhabitants of lotic systems, where they construct burrows in sandy or gravelly substrates and employ filter-feeding mechanisms. Adults are distinguished from the related genus Raptoheptagenia by the absence of anastomosed crossveins in the stigmatic area of the forewing and by having foretarsi shorter than the tibiae. The genus has been documented across North America, Europe, and Asia, including the Western Himalaya.
Leptohyphes
little stout crawler mayflies
Leptohyphes is a genus of small, robust mayflies in the family Leptohyphidae, commonly referred to as "little stout crawler mayflies." The genus contains approximately 18 described species distributed primarily in the Neotropics, with a concentration in South America. Species in this genus are characterized by their crawling behavior and compact body form. The genus was established by Eaton in 1882.
Myxophaga
Minute Bog and Skiff Beetles
Myxophaga is a small suborder of Coleoptera comprising approximately 65 described species across four extant families: Lepiceridae, Hydroscaphidae, Sphaeriusidae, and Torridincolidae. These beetles are among the smallest in the order, ranging from small to minute in size. All members are aquatic or semiaquatic, with many species inhabiting hygropetric environments—thin water films on rock surfaces in running water. The suborder is characterized by distinctive morphological features including clubbed antennae with fewer than nine segments, open mesocoxal cavities, and apically rolled hind wings in resting position.
Narpus
riffle beetles
Narpus is a genus of riffle beetles in the family Elmidae, established by Casey in 1893. The genus contains three described species: Narpus angustus, Narpus arizonicus, and Narpus concolor. These beetles are restricted to western North America and are strongly associated with clean, fast-flowing stream habitats. As members of the Elmidae family, they are adapted to life in running water environments.
Neoplasta
Neoplasta is a genus of dance flies in the family Empididae, subfamily Empidinae, tribe Hemerodromiini. The genus contains approximately 27 described species distributed across the Americas, with records from North and South America. At least one species, N. parahebes, has been studied in detail and exhibits a life cycle tied to submerged decaying wood in freshwater streams, with predatory habits in both adult and larval stages.
Perlodidae
perlodid stoneflies, stripetails, springflies, Stripetail and Springfly Stoneflies
Perlodidae is a family of stoneflies comprising at least 50 genera and over 350 species, with fossil records extending to the Triassic. Adults are commonly known as stripetails or springflies and typically emerge from April to June. The family is characterized by larvae with flattened bodies, patterned heads and thoraces, long tails, and divergent hind wing pads that lack the branching thoracic gills found in similar stonefly families.
Protoptila
Protoptila is a genus of caddisflies (Trichoptera) in the family Glossosomatidae, subfamily Protoptilinae. The genus is primarily Neotropical in distribution, with numerous species described from Central America, northern South America, and Mexico. Species-level taxonomy relies heavily on male genitalia morphology. The genus has been subject to multiple regional revisions, with 19 species recorded from Costa Rica alone and new species continuing to be described.
Psephenidae
Water Penny Beetles, Water Pennies
Psephenidae, commonly known as water penny beetles, is a family of aquatic beetles in the order Coleoptera. The family comprises approximately 272 species in 35 genera distributed across all continents in both tropical and temperate regions. Larvae are fully aquatic and bear a distinctive flattened, circular shape resembling a penny, from which the common name derives. Adults are typically terrestrial, short-lived, and non-feeding. The family is divided into two subfamilies: Eubriinae and Psepheninae.
Psepheninae
water-penny beetles
Psepheninae is a subfamily of Psephenidae (Coleoptera: Polyphaga) containing water-penny beetles, named for the distinctive flattened, oval larvae that resemble pennies. The subfamily includes at least six genera: Psephenus, Psephenops, Pheneps, Psephenotarsis, Psephenopalpus, and Belicinus. Members are strictly aquatic and occur in the New World from North America through Central America to South America.
Rhyacophiloidea
Rhyacophiloidea is a superfamily of caddisflies (order Trichoptera) established by Stephens in 1836. The group has been treated variously in classification systems, sometimes encompassing the entire suborder Spicipalpia when that group is ranked as a superfamily within Annulipalpia. The superfamily includes families of free-living caddisfly larvae that do not construct the portable cases characteristic of many other trichopteran groups.
Sweltsa
green stoneflies
Sweltsa is a genus of green stoneflies in the family Chloroperlidae, established by Ricker in 1943. The genus comprises more than 50 described species worldwide, with documented diversity in North America and Asia. Species are small to medium-sized stoneflies recognized by their characteristic green or yellow-green wing coloration. Adults are typically collected in mid-summer months in mountainous stream habitats.
Tanyderidae
Primitive crane flies
Tanyderidae, commonly called primitive crane flies, are a small family of long, delicate nematoceran flies with about 40 extant species. They represent a relict lineage within Diptera, retaining primitive wing venation including five complete branches of the radial vein. Adults are recognized by their spotted or mottled wings and are typically found near streams, often resting on vegetation or hanging beneath bridges. Larvae inhabit wet, decaying wood or sandy and gravelly stream margins. The family has an extensive fossil record dating to the Late Triassic, with numerous extinct genera known from amber deposits.
Trichoclinocera
Trichoclinocera is a genus of aquatic dance flies in the family Empididae, subfamily Clinocerinae. The genus contains approximately 30 described species distributed across the Holarctic and eastern Asia, with 16 species recognized from the Nearctic region and nine from Japan. Species are organized into six species-groups based on morphological characteristics, primarily of the male terminalia. The genus was established by Collin in 1941 and has undergone significant taxonomic revision, with Seguyella and Acanthoclinocera recently synonymized under Trichoclinocera.
Uenoidae
Stonecase Caddisflies
Uenoidae is a family of caddisflies (Trichoptera) commonly known as stonecase caddisflies. The family comprises approximately 7 genera and at least 80 described species, distributed across North America, Asia, and Europe. Larvae construct portable cases using mineral materials, hence the common name. The family was revised taxonomically in 1988 to include the subfamilies Uenoinae and Thremmatinae, incorporating genera formerly placed in separate families. Studies of Neophylax species demonstrate univoltine life cycles with temporal segregation between co-occurring species.