[f. BOAT sb.] A species of water-bug (Notonecta glauca), whose body resembles a boat.
1753. Chambers, Cycl. Supp., Boat-fly, a water-insect … he swims, says Moufet, on his back.
1860. Gosse, Rom. Nat Hist., 15. The merry little boatflies are frisking about, backs downwards, using their oar-like hind feet as paddles.
