The fly was indeed green, rather than blue. Over several days last year, I saw a few of these green fellows at the same patch of blackberry runners - of course, they could have been the same one, rather than multiple individuals. (In my limited experience, it doesn't seem uncommon for a given identifiable individual to hang out in a given area for several days or more.) This year, however, I've only seen blue ones. I'll keep a special watch for green ones, should they show up again this year.

As a side note, after reading your comment from Dr. Whitworth, I played around with the original image to see if the white balance was correct. All white balance adjustments I did, except one, kept the fly's abdomen green. The one adjustment that favored blue turned the entire fly's thorax a rich metallic blue, but still left the abdomen with much of the green I originally saw.

As a general rule when taking photos, I adjust the white balance to match conditions as they change. As for other camera adjustments that might influence color, I have everything set to standard, so as not to impact the true color of specimens. When preparing images for BugGuide, I only crop and occasionally increase focus or sharpness, but never anything that effects color, hue, saturation, etc.

:-P)

"could be Protocalliphora, still can't be sure"

i really appreciate your detailed explanation and will forward it to Dr. Whitworth -- maybe he'll look harder and slap us with a fancy ID :-]

The "screwworm fly" does not range that far north, as far as I know, and has been largely eradicated from the U.S. altogether with that amazing sterilization factory back in the what, early 1970s? This is actually a "bluebottle" fly of some sort (note the entire body is not metallic, only the abdomen).