Tiny bee or wasp spotted whilst I was photographing nesting Megachile. I had half an eye open for Coelioxys bees but this seems much too small. The walls of the tubes measure2-4mm, so this bee/wasp is around 5mm.
Any help gratefully received.
Identified as a Chalcidoidean parasitic wasp by Santhosh Shreevihar at BWARS. With thanks.