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. It is a widespread bug but much less abundant than N.glauca and is found in more peat and acidic habitats and highlands above 500 to 700 feet where it replaces it. It is thought to be more tolerant of cold water (SWL, 1959).

The lifecycle, breeding and feeding is very similar to N.glauca.

Distribution:

Found in 12 sites in Northants but that number is increasing every year as we increase the surveying but with only 8 10km squares it is still scarce in Northants. The main concentration is in particular borrow pits at Yardley Chase. Here the water is more acidic in these specific ponds. Otherwise in the county they are scattered around the more North west of the county.

Habitat:

At altitude this replaces N.glauca but also associates with Peat, acid areas and bog pools. Peter Kirkby also found an association with base rich lowland sites over clay. In Northants we do have more acidic areas and many sites over clay.

Identification:

Simplistic again this can be differentiated from the other 3 Notonectidae by appearance. The ground colour of the forewing is dark with two cream flashes.

N.glauca can be confused as they are variable, and dark specimens can be common. We have especially found that with some samples at Tichmarsh, Irthlingborough and Higham Ferrars which have since been re-determined from N.obliqua to N.glauca.