I don't pretend to know the identity of this colorful fly—and I don't have it in me this morning to flip through a gazillion images on BugGuide.Net—the best insect ID-ing resource I know—in an exasperating attempt to key it down as to exact species. I suspect it's a member of the Calliphoridae (Blow Flies) family, also known as Bluebottles and Greenbottles.
Calliphoridae comes from the Greek: callos, "beautiful," plus phor, "bearing." A fly bearing beauty. Which is certainly the case. For it was indeed the small fly's dazzling metallic coloring that first caught my eye—turquoise and emerald and ruby-red, shimmering like a jewel in the sunlight.
As I held the camera to my eye and adjusted the fine focus of the lens, I noticed the tiny twisting green vine—scarcely larger in diameter than a human hair—off to the right and adjusted my framing to include it in the photo. And no, I don't know what it is, either.
Ignorance can still be bliss. I do know I like the juxtaposition of the vivid fly and curlycued vine. A bit of mystery only enhances their beauty.