Found wandering about a patch of Frostweed, Verbesina virginica, in my yard. Other shots show they have finished mating and the male is just riding around, likely "mate guarding"--preventing the female from having another mate before oviposition. The male and female are about the same size--something I had not seen in any photos here. Similar mate-guarding behavior is seen in the Wheel Bug, where the female appears to be much larger than the male:

Captured and measured after this photo was taken.
I'm calling these Pselliopus cinctus. The two common species in my area are supposed to be that and Pselliopus barberi, which is apparently bright orange. See discussion and references on guide page for the genus.