At the back of Midsummer Pond I spotted a mine on an ivy leaf. This will be caused by the larvae of an Agromyzid fly Phytomyza ilicis, a common species everywhere though this is the first time I have seen it in GSM3. It was thought there might be more than one fly causing mines in holly leaves, by it now seems only P. ilicis is the culprit in the British Isles. The holly here also has suspiciously flat leaves and might have Ilex x altaclerensis blood in its veins.
I photographed another fly too, this one on an ivy leaf. On most days of the year there are a few species like this wandering round GSM3 and settling on sunlit leaves if the sun is out. There is a large number of lookalike species and this one might belong to the very large genus Fannia. In the past I caught some of these leaf-loving visitors and brought them home to work out an identity. It was a difficult but satisfying operation needing microscopic examination of hairs and bristles on the thorax and legs and sometimes of dissection and slide mounting of critical structures. Now with failing eyesight and shaking hands such activities are a thing of the past and the flies can enjoy their leaves in peace.
