I was unhappy with an ID to the mere genus level, so I went to the website of the University of Mississipi, where execellent keys to Ant species of South-Eastern states are available.
D. mariae (described by the great swiss myrmecologist A. Forel, yeah!) is the only one of four species with such extensively red coloration. One could almost say, a Dolichoderus dressed up as a Mound Ant! :-) More seriously, these ants do probably mimick red Acrobat Ant species.

These primitive odorous ants have a peculiar habitus, quite recognizable on the uppermost worker. Most species are arboreal, nesting under bark or in dead twigs. As for the Aphids, I cannot help you, although most species associated with Pinaceae belong to the genus Cinara.