More photos of the blue chalcid wasps that I first noticed back in late August. I have now identified these as Ormyrus sp. of the family Ormyridae (order Hymenoptera). The Ormyridae is a small family with only 4 species recorded in the UK. They are closely related to the Torymidae, the family that I originally thought these wasps belonged to. Their most obvious distinguishing features are their metallic blue-green abdomens which look as of they have been embossed with a pattern.
The first two photos are of females walking across knopper galls on oak trees. This figures because Ormyrus sp. lay their eggs on the larvae of Andricus quercuscalicis, the Cynipid wasp that causes knopper galls.
The following female seems to have a gold band at the front end ofthe abdomen.
And now a couple of males:
The above photo was taken on 2009-09-10, all the rest on 2009-09-05. All were taken in Whiteknights Park, Reading University grounds, Reading, UK.
These are probably Ormyrus nitidulus (= Ormyrus tubulosus). See the images half way down this page.