Also called fruit flies, I come across these on my local walks on Burdock. This species is called Terellia tussilaginis, and more can be discovered about it on a previous blog via the link.
Photograph of Terellia tussilaginis taken July 2016, local field margin, Staffordshire. © Pete Hillman 2016. Camera used Nikon D3200, with Sigma 105mm macro lens.