by Ian Bushell
This is Xyphosia miliaria, a species of Tephritidae or fruit fly. It is so small and so rarely noticed that it appears to have no common name.
It is quite a common fly that thrives in places like the reserve with damp areas and lots of creeping thistles. It is small so I was lucky to see it; 5 to 8mm long with a wing span of 15 to 18mm. It has a distinctive yellow and orange body, large orange/red compound eyes, and the wings are patterned with black. This one is a female, the abdomen has at its end a dark brown, pointed ovipositor.
Header image and  Xyphosia miliaria by Ian Bushell (03.06.21 SCP/NR)  creeping thistle by DKG (2019 SCP)
Adults fly throughout the summer, from May to September, feeding on the nectar and pollen of various flowering plants. The mated females lay their eggs in the flower buds of creeping thistles, where the larvae hatch and feed.