Promachus rufipes, the so-called "Red-footed Cannibalfly", which is common in the Southeast. (The similar Promachus hinei replaces it west of the Appalachians.) There were a number of these buzzing about on low vegetation at the Eno River. They were looking for prey, and mates--this one, a female, coupled with a male just after I thook this shot, but they did not let me capture the moment. They are quite an odd sight, coupled tail-to-tail, buzzing through vegetation, somehow staying airborne for the most part. The genus name, Promachus is fitting--it was a Greco-Roman military term, meaning "fighter of the first rank", i.e. the biggest, toughest soldiers. That is certainly true of these flies--at up to 35 mm long, they can take down almost any flying insect.  Edit. Remarkably, this species has been reported to attack and take down Ruby-throated Hummingbirds--see This Week at Hilton Pond.