Nick Upton / Lesser dung / Black scavenger fly (Musca / Sepsis cynipsea) male displaying by flicking its wings. Wiltshire pastureland, UK, April.

Simon Colmer / Swarm of Manure flies {Sepsis fulgens} Sussex, UK - swarming is common in autumn

Michael Durham / Blue Bottle Fly (Calliphoridae) lands on the pelage of a dead Townsend's Mole while another is already feeding. These flies are attracted to the odor of the decaying animal

Premaphotos / Manure fly (Sepsis fulgens). Part of a huge swarm on vegetation, possibly aggregating for sexual purposes, UK