The greater water boatman or backswimmer is a native aquatic insect common in most freshwater habitats. They grow to around 2cm and are efficient predators feeding on other insects, worms, tadpoles, froglets and sometimes small fish.
Greater water boatman (Notonecta glauca)
Water boatmen in the UK are divided into to groups, "greater" and "lesser" water boatmen. There are 4 Greater water boatman species. All of them swim on their backs as opposed to there front, like Lesser water boatmen.
Notonecta glauca is the most common and well known. They breed in the spring and deposit eggs in the leaves and stems of aquatic plants. The young are small and transclucent green and go through several moults before becoming adult water boatmen.