Aquatic predatory bug living mostly in fresh water. The adults are about 15 mm/0.5 in long and rest upside down at the water surface to breathe. When disturbed they dive, carrying with them a supply of air trapped under the wings. They have piercing beaks, used in feeding on tadpoles and small fish.

Classification
Backswimmers belong to the genus Notonecta, family Notonectidae in suborder Heteroptera, order Hemiptera (true bugs), class Insecta, phylum Arthropoda.

Females have a sharp ovipositor to pierce the stems of aquatic plants. In each notch one egg is laid; each female lays a total of approximately 60 eggs over a period of a few weeks. Backswimmers fly readily from pond to pond.

Four species of backswimmer are found in Britain. The most common is Notonecta glauca found in most British ponds and lakes. The others are: N. obliqua; N. maculata, with mottled elytra (wing cases), often found in freshwater habitats in southern England; N. viridis, found mainly in brackish waters.