One of the best ways to see some new insects is to leave the back porch light on a bit during these dog days of Summer. Here is a visitor to our porch last night in Baywood/Grayson County, VA. I believe that this is an adult mayfly, possibly a burrowing mayfly of the genus Hexagenia.
If anyone knows better please inform me. This group lives for long periods as a larva in the sediments of streams and lakes and thus the immature form is rarely seen. In contrast the adults do not feed and die after about one day, hopefully after reproducing- thus the name of the order Ephemeroptera (ephemeral life). A pretty strange life reminiscent of periodical cicadas.