Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
Cluster flies (Calliphoridae: Polleniinae: Pollenia) of North America
By Adam Jewiss-Gaines, Stephen A. Marshall, and Terry L. Whitworth
Canadian Journal of Arthropod Identification, 2012
Cite: 616629 with citation markup [cite:616629]
Photographic key and brief notes about Pollenia species known from North America.

HTML: http://www.biology.ualberta.ca/bsc/ejournal/jmw_19/jmw_19.html
PDF: http://www.biology.ualberta.ca/bsc/ejournal/jmw_19/jmw_19.pdf

Very Good info & guide!
The photos in the key show me just what to focus on when I shoot my next cluster fly!

marvelous.
any chance this will help sorting out BG holdings? what do you think?

 
Maybe
I can't speak for John F. Carr, but I just identified a Pollenia I photographed last year to species using this key. It does require a microscope or very detailed macros of a fly. Not sure most of our submissions have enough detail.

 
Pollenia identification
I'm glad to see some people using the key and enjoying it! Thanks for the kind comments!

Unfortunately, yes it's tough to look at previous photos and identify a Pollenia down to species level. The details are very minute so many of them are tough to ID unless you have a very specific shot. That being said, P. vagabunda and P. griseotomentosa stand out a bit more and might be a tad easier to identify.

I'll take a look through photos on bugguide and see what I can do, though!