THE XERCES SOCIETY FOR INVERTEBRATE CONSERVATION

Aquatic Invertebrates in Pacific Northwest Freshwater Wetlands
An Identification Guide and Educational Resource

Backswimmers are very common in still waters, where, as their name implies, they swim upside-down, using their paddle-shaped hind l;egs as oars to propel them through the water. They also rest on their backs with their hind end at the water's surface, obtaining oxygen from air trapped beneath their wings. Their unique behavior is reflected in their coloration--as the photos above show, notonectids tend to have a dark ventral surface and light dorsal surface, which is the opposite pattern of most aquatic organisms.

Their body is elongate and generally larger than the similar looking water boatmen (Corixidae), and their dorsal surface is usually a greenish white (darker in Corixidae). The antennae are short and not clearly visible, and the beak is narrow, tube-like and segmented. The hind legs are paddle-shaped and lack claws, and their forlegs are not scoop-shaped forelegs as seen in corixids.