Hi Mep,
Made me smile too, but I can't think why.
Our small rural estate is surrounded, just about, by farmland and the little flies seem to vary according to the crops planted in the fields. In the 1970s it was all barley. I remember coming home one day to find a black band about 9 inches wide around the perimeter of every pane of glass - on the inside. It was summer, we had left the small (hopper) windows open. The locals called them barley flies and I was told that when the heads of barley ripen they 'open' and thousands of these small flies come out.
These days the crops are usually rape seed and we get a different small fly. They're very small and infuriating.