Water Bugs (infraorder Nepomorpha) are a diverse group containing the aquatic members of the True Bugs. They include Giant Water Bugs (family Belostomatidae) and Water Scorpions (family Nepidae) that crawl on the bottom, Backswimmers (family Notonectidae) and Water Boatmen (family Corixidae) that swim just under the surface, and Toad Bugs (family Gelastocoridae) that crawl on the muddy shores.
Kirby’s Backswimmer ( – 0.4-0.6″. Back is a mix of blacks, browns, and whites, but since it swims on its back it will usually show its brownish belly. Rear legs especially long for swimming. Found in water bodies. (photo © ) Notonecta kirbyi Thomas J. Bright)
– to 0.45″. Body is predominantly white with black markings including all-black pronotum. Found mostly in ponds/pools but will use lakes, streams, and rivers. Feed on mosquito larva and other small arthropods. (photo © ( Grouse-winged Backswimmer Notonecta undulata) Kurt Steinbach)
V-marked Backswimmer (– 0.4-0.5″. White with black markings and brownish “V” on black pronotum. Like other backswimmers, uses surface tension to cling to water’s surface upside-down. Backswimmers have painful bite. (photo © Notonecta unifasciata) Chris Evers)
– to 0.45″. Similar to backswimmers but legs of uniform length and swims right-side up. Numerous very similar-looking species in our region. Feed on algae, small invertebrates, and debris. Found in ponds (photo © Water Boatmen ( Corixidae) Eric Carlson)
– 0.4″. Rough round body with distinct eye stalks. Mottled in grays, browns, rust-brown, and blacks. Found on shores of lakes and streams, spending most time on land unlike other water bugs. Eats small insects. (photo © ) Big-eyed Toad Bug ( Gelastocoris oculatus Howard Bruner)
American Giant Water Bug (– 2.0-2.4″. Huge brown bug with front pair of legs held forward as substantial pinchers. Found in ponds and shallow parts of lakes and slow streams. Eat insects, crayfish, tadpoles, and small fish. (photo © Lethocerus americanus) Jim Johnson)
– 1.3-1.7″. A long slender brown insect that walks on four legs while using the front two as pinchers. A thin breathing tube protrudes from the back. Feeds on insects, tadpoles and small fish in ponds and slow streams. (photo © Brown Waterscorpion () Ranatra fusca Andrew Cope Emlen)
Water Striders (family Gerridae of infraorder Gerromorpha) are thin-bodied insects with long legs that use surface tension to “walk” on the water. They are predatory, grabbing aquatic insects that move near the water’s surface as well as terrestrial insects that fall in the water. Included in this section are the closely related Water Treaders (family Mesoveliidae) and Riffle Bugs/Small Water Striders (family Veliidae), which have similar habits but more robust bodies and shorter legs.
– 0.5-0.65″. Our most common water strider, identified by brown back, large size, and long first antenna segment. Found in ponds, lakes, rivers, and streams. (photo © Common Water Strider ( Aquarius remigis) beeoutside)
– 0.6-0.8″. The largest water strider species, also identified by reddish-brown coloration and short first antenna segment. (photo © ) Great Water Strider ( Limnoporus notabilis Hannah Floyd)
Blue-winged Water Strider – 0.25-0.3″. A small water strider with bluish tint to wings and white stripe on lateral margin of pronotum. Can be found in almost any kind of water body from rain puddles to rivers, usually at the margins in vegetation. (photo © ) ( Gerris buenoi robertweeden)
Western Water Strider (– 0.35-0.4″. Medium-sized with no pale stripe on front margin of pronotum. Found at the margins of ponds and small lakes. (photo © Gerris incurvatus) Jim Moore)
Mulsant’s Water Treader (– 0.15″. Very small white body with green or dark wings and yellowish legs. Found near masses of algae and floating plants at the margins of standing water. (photo © Mesovelia mulsanti) Mike Quinn)
– 0.05-0.1″. Extremely tiny bugs with relatively short legs that skitter on the water’s surface. Found in ponds with duckweed. (photo © ) Minute Water Striders ( Microvelia sp. Barbara L. Wilson)