Water-quality-indicator
Guides
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.
Bosmina
water flea
Bosmina is a genus of small cladoceran crustaceans commonly known as water fleas. Members are distinguished from the related genus Bosminopsis by having antennae that are separated at their bases rather than fused. Bosmina species are filter feeders that consume algae and protozoans approximately 1–3 μm in size, using a dual feeding mechanism involving mesh-like setules on the second and third legs for filtering while the first leg grasps particles. The genus exhibits notable morphological plasticity, particularly in posterior mucrones and anterior antennules, which vary in response to predation pressure. Some Bosmina species have become invasive outside their native ranges, posing threats to aquatic ecosystems.
Callibaetis
Speckled Duns
Callibaetis is a genus of small minnow mayflies in the family Baetidae, comprising at least 30 described species distributed across North and South America. The genus has been taxonomically problematic, with recent phylogenetic work confirming its monophyly and establishing four subgenera. Species occupy diverse lentic habitats including ponds, lakes, and wetlands, with some populations adapted to variable salinity conditions.
Callibaetis pictus
Speckled Dun
Callibaetis pictus is a small minnow mayfly in the family Baetidae, commonly known as the Speckled Dun. It is distributed across Central America and North America, including all of Mexico and the northern and southwestern United States. Like other mayflies, it has an aquatic nymphal stage lasting months to years, followed by a brief adult lifespan measured in hours to days. The species is part of the EPT index (Ephemeroptera, Plecoptera, Trichoptera) used to assess water quality in environmental monitoring.
Cloeon
Double-gilled Pond Creepers
Cloeon is a cosmopolitan genus of mayflies in the family Baetidae, commonly known as Double-gilled Pond Creepers. Species in this genus are aquatic as larvae (naiads) and inhabit diverse freshwater environments. At least one species, C. dipterum, is known to give birth to live naiads rather than laying eggs externally. The genus has been studied for its tolerance to environmental stressors including temperature and oxygen fluctuations.
Elminae
riffle beetles
Elminae is a subfamily of riffle beetles (family Elmidae) comprising at least 120 genera and over 1,300 described species. Members are primarily aquatic, inhabiting running water habitats across all major biogeographic regions. The subfamily exhibits considerable morphological diversity, with some genera showing pronounced secondary sexual dimorphism and miniaturization traits.
Hexagenia atrocaudata
Lake Hex
Hexagenia atrocaudata is a burrowing mayfly species in the family Ephemeridae, known from North American lakes and rivers. As a member of the common burrower mayflies, it spends the vast majority of its life as an aquatic nymph in bottom sediments, emerging as a short-lived winged adult for reproduction. Adults lack functional mouthparts and do not feed. Mass synchronous emergences can occur, producing swarms that attract fish and anglers alike. The species serves as an important indicator of clean freshwater ecosystems and provides substantial food resources for aquatic and terrestrial predators.
Isonychia intermedia
Isonychia intermedia is a species of mayfly in the family Isonychiidae. Like other members of its genus, it is an aquatic insect with a life cycle consisting of an extended nymphal stage in freshwater habitats followed by a brief adult stage. The species is found in North America and is part of the EPT (Ephemeroptera-Plecoptera-Trichoptera) assemblage used in water quality biomonitoring. Adults are known to anglers as 'slate drakes' due to their dark wing coloration.
Neoleptophlebia assimilis
Southeastern Prong-gilled Mayfly
Neoleptophlebia assimilis is a species of prong-gilled mayfly in the family Leptophlebiidae. It is known from the southeastern United States. The species belongs to a genus characterized by gills with divided, finger-like lobes. Mayflies in this family are typically associated with running water habitats and serve as important indicators of water quality.
Optioservus browni
Brown's optioservus riffle beetle
Optioservus browni is a species of riffle beetle (family Elmidae) described by White in 1978. The species is known from North America and is part of a genus of aquatic beetles typically found in flowing water habitats. Like other elmid beetles, it is adapted to life in fast-moving streams and rivers.
Palingeniidae
spiny-headed burrowing mayflies
Palingeniidae is a family of large mayflies commonly known as spiny-headed burrowing mayflies. Adults are characterized by having more than four longitudinal cross-veins on their wings, with males possessing short, wide pronota and well-developed legs in both sexes. Female cerci are shorter than the body. Nymphs are burrowers in muddy substrates of large rivers. The family includes notable species such as Palingenia longicauda, the largest European mayfly at up to 12 cm in length.
Pteronarcys proteus
Appalachian Salmonfly
Pteronarcys proteus, commonly known as the Appalachian salmonfly, is a giant stonefly in the family Pteronarcyidae. It is among the largest stonefly species in North America. Adults are known for their distinctive appearance and are most frequently encountered near clean, fast-flowing streams. The species has been documented in the eastern United States, with records from Kentucky through New England.
Smicridea fasciatella
net-spinning caddisfly
Smicridea fasciatella is a net-spinning caddisfly in the family Hydropsychidae. It is the primary species responsible for nuisance swarming events along the Colorado River in Bullhead City, Arizona, where synchronized mass emergence of adults creates significant quality-of-life impacts for residents. The species belongs to the fasciatella species group, which occurs across the Americas from the southwestern United States through Central America and South America. Like other hydropsychid caddisflies, its larvae are aquatic filter-feeders that construct capture nets to obtain food from flowing water.
Zapada cinctipes
Common Forestfly
Zapada cinctipes, the common forestfly, is a small spring stonefly in the family Nemouridae. Adults measure 5–8 mm in body length and emerge primarily from mid-March to mid-April, with some appearing as early as late February. The species is univoltine, completing one generation per year. Nymphs are aquatic shredders that feed on decaying leaf material in flowing waters.