I was excited to see these tiny (7 mm) flies on the lily pads in my pond today. This is an attractive fly with a lime green thorax. The male has conspicuous white wing tips and is easy to identify. The hairs on top of the thorax are in two neat rows. It lives in damp places with lush vegetation and is often seen resting on mud or on the water surface. May to August. A mating dance precedes copulation. The male performs a courtship display where the conspicuously marked wings are raised and lowered, a bit like an airport marshal guiding a plane to a parking spot with a pair of batons. Wingspan is directly related to body size, so the better (or bigger) the display, the healthier the male. See an encounter in my next photo. Quite common and widespread in England and Wales, fewer records from Scotland.