From back in the middle of the summer, an orange and black sawfly. At first I thought this was Arge sp. but I have just noticed that it has too many segments in its antennae (about 8, as opposed to the 3 that Arge have), so I now think it is Athalia sp. (Hymenoptera: Tenthredinidae). The black coloration on the thorax does seem to be quite variable in these orange and black sawfly species.
Photos taken in Whiteknights Park, Reading University grounds, Reading, UK, on 2009-07-14.