Hello everyone
In terms of and ID thread, my recommendation would be to sign up to the Hoverfly Recording Scheme website
Hoverfly Recording Scheme - Index - I've always dealt with records there and there are several others who regularly trawl the site and provide advice. The shot can then be posted on Wild About Britain with more confidence. However, I will keep an eye on records and give opinions from time-to-time.
Going back to the general principles of ID from photos, I'm afraid I hold quite a bit of sceptocism about ID from photos. At a personal level I quite frequently find myself saying "I am just not sure because I want to see x or y". Maybe I'm just not sufficiently competent but I generally avoid doing field identifications on many of the difficult genera. In the case of Eupeodes for example, it is a bit of a nightmare genus with small characters that are not revealed in photos e.g. microtrichia on the wings. I know some people exude great confidence about ID of photos, and I confess I would err towards the same ID. But, I'm afraid I have also found that I've been wrong - so I don't put a name to anything that might be confused with something else.
Stuart Ball and I have developed a classification of ease of identification which shows just how tricky we and other specialists regard hoverflies. In tyhe Case of E. lapponicus I think we would expect to see a specimen because it is just too tricky.
Regards
Roger