Size estimated. This one has me flummoxed, but that is not hard to do with flies. I thought it was a Systoechus, but now I'm rather liking Sparnopolius confusus. Wing venation seems to agree with images we have here, but I'm not good at determining those. Antennae also seem to agree. Some images for comparison:


Looking at the wing venation and antenna shown for Sparnopolius confusus and similar species in Herschel Raney's Key to the Bombyliidae of the eastern US, it does seem to be a match. I'm going to be bold, though perhaps foolish, and place images there. Seems to be a male, based on eyes that touch at top of head--see other images here.

Confirmation/refutation much appreciated!