Freshwater
Guides
Unionicolidae
water mites
Unionicolidae is a family of water mites in the order Trombidiformes, comprising approximately 5 genera and at least 40 described species. Members are primarily freshwater aquatic arachnids distributed worldwide. Many species, particularly in the genus Unionicola, exhibit parasitic relationships with freshwater molluscs, feeding on host mucus and tissue. The family represents a significant component of Arachnida diversity in aquatic ecosystems.
Usingeriessa
Usingeriessa is a genus of moths in the family Crambidae, subfamily Acentropinae. The genus was established by Lange in 1956 and contains approximately 11 described species distributed primarily in the Neotropical region. These moths are part of a group commonly known as aquatic or semi-aquatic crambid moths, though specific ecological details for the genus remain limited.
Utacapnia
small winter stoneflies
Utacapnia is a genus of small winter stoneflies in the family Capniidae. The genus contains approximately 11 described species, most of which were first described by entomologists Alan V. Nebeker and Arden R. Gaufin during the 1960s. Species in this genus are primarily distributed in the Rocky Mountains of North America. As winter stoneflies, members of this genus are active during cold months, a trait characteristic of the family Capniidae.
Uvarus lacustris
Uvarus lacustris is a small predaceous diving beetle in the family Dytiscidae, first described by Thomas Say in 1823. It belongs to the tribe Bidessini within the subfamily Hydroporinae. The species is documented from North America, with confirmed records from Canada (Ontario) and the United States. As a member of Dytiscidae, it is an aquatic predator, though specific ecological details remain poorly documented in published literature.
Vatellus
Vatellus is a genus of predaceous diving beetles in the family Dytiscidae, tribe Vatellini. The genus contains 15 described species distributed primarily in the Neotropical region, with most species described by K.B. Miller in 2005. Members are aquatic beetles adapted to freshwater habitats.
Veliidae
riffle bugs, small water striders, broad-shouldered water striders, ripple bugs
Veliidae is a large family of predatory true bugs in the suborder Heteroptera, comprising approximately 1173 species across 66 genera. Members are small (1.5–6 mm), surface-dwelling insects that walk on water using surface tension and hydrophobic leg adaptations. They are distinguished from the related family Gerridae by their broader pronotum, smaller size, and internal genitalia differences. The family has a cosmopolitan distribution excluding Antarctica, with centers of origin in the Indo-Malayan region and the Caribbean.
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.
Xanthochlorus
Xanthochlorus is a genus of long-legged flies (Dolichopodidae) established by Loew in 1857. Species in this genus are small to medium-sized predatory flies with characteristic yellow-green coloration. The genus occurs in the Holarctic region, with records from Scandinavia and North America. Like other dolichopodids, members are likely associated with moist habitats near water bodies.
Xylotopus par
Xylotopus par is an aquatic xylophagous midge in the family Chironomidae. The larvae colonize submerged wood substrates in freshwater streams, feeding on decaying wood. Populations exhibit plastic phenology, with development rates varying based on wood substrate quality—larvae in fresh, introduced wood can complete development in a single summer, while those in indigenous logs normally require a full year. The species has been studied for its unique bacterial associations in the larval midgut, where morphotypically uniform bacteria form a well-defined band in the posterior midgut's ectoperitrophic space.
Yoraperla
roach-like stoneflies
Yoraperla is a genus of stoneflies in the family Peltoperlidae, commonly known as "roach-like stoneflies" due to their resemblance to cockroaches. The genus contains eight described species distributed across North America and Asia. Yoraperla was established by Ricker in 1952 and is classified within the subfamily Peltoperlinae.
Zaitzevia parvula
riffle beetle
Zaitzevia parvula is a species of riffle beetle in the family Elmidae. It was described by Horn in 1870. The species is found in North America, with records from Alberta and British Columbia in Canada. Two subspecies are recognized: Z. p. parvula and Z. p. thermae.
Zavrelimyia
Zavrelimyia is a genus of non-biting midges in the family Chironomidae, subfamily Tanypodinae, and tribe Pentaneurini. The genus was established by Fittkau in 1962 and is placed within the predatory midge lineage Tanypodinae. Species in this genus are aquatic in their larval stages and are part of the diverse chironomid fauna found in freshwater habitats.
Zavrelimyia fragilis
Zavrelimyia fragilis is a species of non-biting midge in the family Chironomidae. Like other members of this family, it belongs to the order Diptera and is characterized by a life cycle that includes aquatic larval stages. The genus Zavrelimyia is part of the diverse chironomid fauna, with larvae typically inhabiting freshwater environments. Adult midges are generally short-lived and do not feed.
Zoniagrion exclamationis
Exclamation Damsel
Zoniagrion exclamationis, commonly known as the Exclamation Damsel, is a species of damselfly in the family Coenagrionidae. It is the sole species in its genus and is endemic to western North America. The species was first described by Selys in 1876 and is recognized by its distinctive coloration and patterning. It is a relatively well-documented damselfly with over 300 observations recorded on citizen science platforms.