(the latter name derives from the fact that the body, widest at the middle or hind legs, tapers to the abdomen, giving the impression of broad shoulders), any of the approximately 300 species of the insect family Veliidae (order Heteroptera). Smaller water striders—which may be brown, black, or silvery in colour—occur throughout the world. They are small (usually less than 5 millimetres 【0.2 inch】 long) and stout-bodied; both long-winged and short-winged or wingless forms exist within a species.

The legs are evenly spaced, except in the genus Rhagovelia, which has the middle pair closer to the hind pair. Insects of this genus are often seen running against a rapid current, aided by a fan-shaped arrangement of bristles on its second pair of legs. It can also dive and swim underwater. The genus Velia occurs around moderately rapid streams and bogs. Microvelia, smaller than Rhagovelia, is usually found in swarms along the shore but runs on the water surface when disturbed.