Notonectidae is a cosmopolitan family of aquatic insects in the order Hemiptera, commonly called Backswimmers because they swim upside down. The Common Backswimmer, Notonecta glauca, is widespread in the United Kingdom, where it is known as the greater water boatman, and in Europe. The most common genus of Backswimmers is Notonecta – streamlined, deep-bodied bugs up to 16 mm long, green, brown or yellowish in colour. N. maculata, is distinguished by its mottled brick-coloured forewings.