Similar to the Common Water Boatman with a long, streamlined body and back legs like oars, it can be distinguished by its silvery grey forewings and the fact that it swims on its back. Its middle pair of legs are also much shorter than in Common Water Boatmen and it has large reddish eyes. Often carries a bubble of air on its belly, giving it a silvery appearance.
Latin name: Notonecta glauca
Size: Up to 20mm
Overview
The most common of our 4 native species, this vicious bug is a strong flyer in warmer weather, populating ponds and other still waters in summer. Unlike the Common Water Boatman, it enjoys a leisurely backstroke rather than breaststroke, which is the easiest way to distinguish the two species. Its hairy belly helps it to retain an air bubble there. A voracious predator, it can gobble up other insects, tadpoles and even small fish. Resting on the water’s surface, it detects vibrations from below and dives to investigate. If the culprit is edible, the backswimmer will pierce it with its needle like rostrum and inject it with toxic juices.
In the garden
If you have a pond, this aquatic insect will come. Be careful when pond dipping, backswimmers are irritable invertebrates and will give you a nasty ‘bite’. Their saliva is slightly toxic and will give a painful stinging sensation.