This species has particularly dark wings. Though the abdomen is black and unmarked, the thorax of the female has a purple sheen and the scutellum often has a blue-grey dusting.

Found on umbellifers in damp places.

From late May to October, peaking in July and August.

The larvae live in the mud beside streams and ponds.

Fairly frequent and widespread in most of Britain, though somewhat less so in the north.

Fairly frequent in Leicestershire and Rutland.