The water-bug Notonecta glauca may be observed swimming upside down on the surface of ponds using their long, flattened, hair-fringed hind legs as oars – hence their common name of ‘greater water-boatman’ or ‘common backswimmer’; water tension enables them to remain under the water surface, while their covering of fine hair traps an air film which allows them to absorb oxygen when submerged.
Notonecta glauca commonly preys on insects like mosquito larvae, but it is reported that they do not hesitate to attack prey as large as tadpoles and small fish: the strong front and middle legs grab the prey before the piercing beak is inserted. The backswimmers may also ambush unsuspecting prey by resting on the water surface where they can discriminate between prey and non-prey items by the surface waves produced.
Once they have climbed out of the water, backswimmers will readily fly between ponds.
