Osmia rufa - and opportunistic fly?

[Jason Green]

Hi all

I have a nesting box for bees in the garden, and for the last few years it has been used by Osmia rufa. Today I noticed a small red-eyed fly with a barred abdomen and wings exceeding the length of the body, hanging around and even resting in the entrance to the cells the bees are working on, seemingly unperturbed by two of them as they got close.

Does O. rufa have a parasitic thing associated with it, or is the fly after anything, not necerssarily related to them? Maybe it isn't O. rufa, but another with a fly linked to it that nests in cut canes?

I will post the photos later

Take care,

Jason

[Jason Green]

Here they are... the bee and fly, repectively. The fly was about half the size?



Thanks!

[Geoff F]

Have a look at this earlier post Fly id please could be the same sort of fly. Identified as a Leucophora.

[Jason Green]

Thanks Geoff,

...funnily enough, I was reading that very thread the second I checked on this one! If it is, and I believe an Anthomyiidae, could it's location have been simply coincidental as they go for Andrena sp.?

[Africa]

Your description and photo reminded me of a website I was checking yesterday.
it is a very interesting photographic description of bees, with beautifully detailed photos, search for the section on O. rufa and at the end of it there are photos of a cleptoparasitic fly which lays its eggs on the pollen collected by O. rufa.
Natural History Photographs by Cor Zonneveld
This is the photo of the fly, IDd there as Cacoxenus indagator:
http://www.corzonneveld.nl/hymenopte...2059%20med.jpg

I hope it helps

[Jason Green]

Thanks there Africa - great work there, Africa! Yep, that'll be the one I'm sure. Nice site too. Thanks both.