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You have different species here, might be wise to post them individually, unless you have intended a sample of "Eristalis" species.
Chris Brooks - www.dragonfly-images.co.uk
My Flickr site - www.flickr.com/photos/ceb1298
Which images are the same species? Top right,left etc..
I'm undecided about top left. Bottom left looks like E. pertinax and the two on the right look like E tenax.
Lat/Lng: 52.6, -1.2
OS grid ref: SK5604