backswimmer 仰泳蝽
backswimmer[ noun ]
predaceous aquatic insect that swims on its back and may inflict painful bites
<noun.animal>
backswimmer \back"swim`mer\ n.
any of numerous predaceous aquatic insects of the family
{Notonectidae} (such as {Notonecta undulata}) that swim on
their backs and may inflict painful bites; -- also called
{boat bug}. --[RHUD]
[WordNet 1.5 +PJC]