Hoverfly

A male hoverfly of the Cheilosia albitarsis species group, probably Cheilosia mutabilis (Diptera: Syrphidae). Cheilosia albitarsis or Cheilosia ranunculi (Diptera: Syrphidae).  Initially I thought that it might be Cheilosia mutabilis because of the black on the haltere, but Roger Morris pointed out in the comments below that this is not necessarily diagnostic.

Dark or partly dark halteres distinguish C. mutabilis from C. albitarsis and C. ranunculi, the other two members of the group.

Photos taken in Whiteknights Park, Reading, UK, on 2012-05-18.

Comments

[Roger Morris]

I think this is probably albitarsis/ranunculi as the presence of some dark on the haltere is not entirely diagnostic. The big problem with a photo is getting a judgement of the size/proportions of the insect - C. mutabilis is rather narrower. I don't suppose you have a specimen?

[Tristram Brelstaff]

Thanks Roger. I did wonder as I photographed another one with all-yellow halteres later on the same walk. And no, I don't have the specimen.