any one of numerous aquatic pests of the family Notonectidae that swimming on the backs by way of broadened, oarlike hind legs.
some of different aquatic insects, associated with family Notonectidae, that swimming on the backs.
any of many predaceous aquatic pests associated with the household Notonectidae (such as for instance Notonecta undulata) that swim on their backs that will cause painful bites; -- also called motorboat bug.
Same as boat-fly.
predaceous aquatic pest that swims on its as well as may inflict painful bites