Length: up to 14 mm. Specimens are usually coloured a uniform shade of pale, mid, or dark brown. But some individuals (or whole populations) can be a creamy colour, or at the other extreme, almost black.

Good photographs required and expert confirmation may be necessary.

Usually found in gentle streams, ponds and lakes.

All year round, though most frequently encountered in summer months. It may be attracted to light.

Will feed on most animals it encounters that are in a recently damaged, immobilised state, leaking body fluids into the water.

In lowland Britain, this is one of the commonest of our species.

Only occasionally recorded in Leicestershire and Rutland, but this may reflect a lack of recording effort.