Hoverfly

A metallic dark green hoverfly, probably a female Melanogaster sp (Diptera: Syrphidae).  Initially I thought it was Lejogaster metallina but Roger Morris corrected me (see in the comments below). 

See here for one I saw last year.

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

Comments

[Roger Morris]

I think your Lejogaster is actually Melanogaster - the antennae are too small and the animal is not particularly metallic.

[Tristram Brelstaff]

I think you're right! In Plate 7 of Stubbs and Falk the wing veins for Melanogaster and Lejogaster show subtle differences and the above seems to match Melanogaster better. However, the size of the antennae is the most obvious difference. I was unduly influenced by the greenish colour of the body. Thanks for putting me right.