These flowers look awful small to offer much to a butterfly but this one persisted, moving steadily from flower to flower. The lack of leaves on this plant gave me a clear view.
He rotated and showed me every side while he was doing it.
Even upside down!
He easily walked across the tops of the flowers.
And hung off the side.
I believe the plant is Brazilian Vervain (Verbena brasiliensis), a non-native plant that grows wild along roadsides, in disturbed areas, old fields. (NameThatPlant.net, A storehouse of information about native and naturalized plants of the Carolinas and Georgia.)