St Mark’s Flies

On a recent visit to Rhossili I had looked forward to seeing Spring flowers in the ancient Vile strip fields on the promontory but, when I arrived, I was disappointed because most of the fields had just been ploughed or mown. The only flowers of interest were the Alexanders (Smyrnium olusatrum) which were flowering in abundance on either side of one of the lanes. Curiously, each plant was covered with large black flies that I had not seen before, St Mark’s Flies (Bibio marci).