[Naturens] Wooly alder aphids, or something else?

Can someone identify the little flying fluffballs that come out on a warmish winter day (and in spring and fall) and fly around in the same area for long periods of time? They fly vertically, up and down, up and down, in a group, and look like they are being juggled by many invisible hands... the group can move laterally while continuing their constant vertical movement. Are they wooly alder aphids, or something else? Many thanks Suzanne at Hatchet Lake