Hi John - unfortunately, based on the photo alone, I can't be definitive about this one, though I probably would opt for a Common Flatwing, including based on habitat. The lateral thoracic pattern is just not clear enough, and the dorsal thorax itself is obscured by the wing to know if there is any real pruinescence there. The angle doesn't give a good view of the shape of the anal appendages. either. So overall, just not enough to go on.