A pair of Macquartia dispar (Diptera: Tachinidae) mating. I caught the male and later identified it using the key of Belshaw (Tachinid Flies, Diptera: Tachinidae, 1993). The females of this species are noticably lighter coloured than the males. They parasitize the larvae of leaf beetles (Chrysomelidae).
Photo taken in Whiteknights Park, Reading, UK, on 2014-04-26.