| There are 32 species in 3 genera found throughout North America. Larvae and adults ranging in length from 5-16 mm can be found in ponds, freshwater pools, and slow flowing streams. Notonectidae are predators, feeding on other aquatic insects and small vertebrates.
Elongated white eggs are cemented to underwater plant stems. The eggs hatch after a few weeks and the first generation adults appear in July.
Notoncetidae are similar to appearance to Corixidae but can be distinguished from them by the differences in their dorsal-ventral coloration, front legs and predatory behavior. The backswimmers swim on their backs, vigorously paddling with their long, hair-fringed hind legs.
Backswimmers are predators and attack prey as large as tadpoles and small fish, and can inflict a painful bite on a human. They dive by holding air trapped in abdominal pockets and can remain submerged for up to 6 hours.