Sepsis cynipsea

2.5 to 3 mm long. There is a dark wing spot on each wing, typical of the Sepsis genus. The hypopleuron (between the haltere and the hind coxa) is pruinose in the anterior part but glossy black on the posterior part. The sternopleuron is entirely pruinose. (Adjust the angle of light to view the pruinosity). The mid femur lacks an anterior seta near the middle (don't confuse with a ventral or anterior-ventral setae) and the mid tibia has 0-1 posterior setae.

Males have a unique ornamentation on the front tibia which is a helpful key ID feature.

Other Sepsis.

• black wing spot
• sternopleuron all pruinose
• hypopleuron pruinose at the front but glossy black at the rear
• no anterior setae on the mid femur
• 0-1 posterior setae on the mid tibia

Unless identified by a recognised expert, a photo is required and the specimen should be examined with a microscope. In the comments box, state the key or ID method used and describe the size and identifying characters.

Around fresh dung.

Although the species might be encountered at any time, the main period is between May and September with a peak in July and early August.

The flies are active by day, and the sexes usually meet for mating around fresh dung where the eggs will be laid.

Widespread and fairly frequent in Britain.

Fairly frequent in Leicestershire and Rutland.