Lethocerus americanus is a giant water bug in the family Belostomatidae, native to southern Canada and the United States. It typically has a length around 5–6 cm (2.0–2.4 in).
Commonly found in ponds, marshes, and on the edges of lakes and slow-moving streams, and creeks, adults and larvae feed on other insects, small crustaceans (crabs/crayfish), tadpoles, snails, and small fish. The adult swims with the aid of its hind legs. A pair of front fore limbs is used for capturing and latching onto its intended prey.