Myzaphis van der Goot
This is a genus for several small aphids that feed on roses and Potentilla. It appears that one species is native to North America (M. canadensis), while one is invasive here (M. rosarum). I have collected both of them, the former without photos but in an unexpected place: New Mexico (considering that the original description was from Ontario, Canada).
Myzaphis rosarum (Kaltenbach)
This species was probably native to Europe, but is now almost everywhere. I have collected it twice (Washington and Oregon) on cultivated Potentilla fruticosa. I collect very frequently and with determination on this plant, yet have only seen Myzaphis a few times.