Cheilosia bergenstammi is a difficult to identify hoverfly, so multiple angle shots are needed. Always associated with Ragwort in Autumn as it is the larva's food-plant. There are quite a few Cheilosia that look very similar. The round, flat orange antennae with hairs on eyes and feeding on Ragwort [autumn Cheilosia prefer white umbellifiers] is a good indication that this is "bergenstammi". The tarsi are extensively pale and the tibia are usually orange with a black ring. Furry type Cheilosia can also be eliminated. A combination of all the above features can then rule out the other Cheilosia. I was pretty sure it was bergenstammi, but had an expert to confirm just in case - which he did.