This species is a backswimmer or greater water boatman thereby mainly swimming upside down with two large hind legs with swimming hairs that look like paddles. However, it is a specialist of hard surfaced habitats. This can include, Concrete tanks and ponds, Dams, around Pontoons, cattle trough's and stoney bottoms/margins.

As with N.glauca they are highly evolved predators and have a sharp rostrum or stabbing mouthpart which they use to feed near or on the surface on drowned insects in it's barren habitats. I would recommend you don't handle these as they can inflict a very painful bite.

Eggs are laid between late August and mid-October, usually upon stones or concrete slabs but sometimes attached to plants. These overwinter and hatch about March and early April, the larvae becoming adult in late July and early August. However, there is at times a secondary cycle: in this the adults overwinter and oviposition takes place in late March and early April - these eggs take about 3 weeks for development. (S&L, 1959)

Distribution:

They are widely distributed across Northants and local wherever the habitat is found. Dams and man made structures around on reservoirs are plentiful in Northants. Across the country they are widespread in England and Wales but not in Scotland

Habitat:

Found in habitats with hard surfaced areas. They are regularly found in cattle trough's both metal and plastic, next to bridges, brick or wooden structures in the water, Dams and overflows of reservoirs, Canal brick structures, lock's and sluices and hard stoney surfaced ponds. It is very evident with this that you find the habitat and also find the bug.

Identification:

Again this can be differentiated from the other 3 Notonectidae by appearance. The ground colour of the forewing is dark orange/brown with a light mottling. N.glauca can be confused as they are variable and dark specimens can be common (also when wet the forewings look darker), however the definitive feature is that if you lift up the forewing of N.maculata it has a black semi-circle on an orange metatonum.