This is common active predator feeding on water flees, Asellus, insect larvae and Gammarus in muddy pools, stagnant canals and lakes where is it lives on the bottom amid dense vegetation. On the bottom of the pond the fore-legs are used to root through the mud and debris. The bug can also run rapidly on dry land. The older literature usually decides this as flightless , but in recent years i have seen it in flight on several occasions (JD, 2007).

After overwintering as adults, the bugs mate from late February onwards. Oviposition mostly occurs between late April and the end of May, the eggs being inserted - for the most part - in rows in stems of aquatic plants. Egg development takes about a month and the five larval instars a further 2 months. The old females live on for some time but by early June only larvae are present. Males are sexually mature as early as November but cannot mate until 3 or 4 months later (S&L, 1959).

Distribution:

This is a South or West species in the UK and with 25 10km squares recorded is very common in Northants although is more frequently found more west of the county. It is found in a variety of still waters but is very well suited to the gravel pits in the Nene Valley and this comes out on the distribution map.

Habitat:

Found in muddy pools, stagnant canals and lakes where is it lives on the bottom amid dense vegetation.

Identification:

It is a large water bug, length 12-15 mm, which is unlike any other British species except for a recent (2004) arrival in Britain, Naucoris maculatus, which at the moment is confined to sites in Kent and Sussex. N. maculatus is smaller (9.8-10.4 mm), lighter in colour and has five more or less distinct dark marks on the pronotum (AC, British Water Bugs).

Juvenile saucer bugs have the same general shape as adults but need careful examination to be certain (TH, 2003).