Boat bug

from WordNet (r) 3.0 (2006)

boat bug
    n 1: carnivorous aquatic bug having paddle-like hind legs [syn:
         {water boatman}, {boat bug}]

from The Collaborative International Dictionary of English v.0.48

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]

from The Collaborative International Dictionary of English v.0.48

Boat bug \Boat" bug`\ (Zool.)
   An aquatic hemipterous insect of the genus {Notonecta}; -- so
   called from swimming on its back, which gives it the
   appearance of a little boat. Called also {boat fly}, {boat
   insect}, {boatman}, and {water boatman}.
   [1913 Webster]

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