It's actually the other way round: Aliasing fills the lower frequencies with a mirror image of the higher frequencies. So where do the higher frequencies come from? From the upsampling that happens before the aliasing. _That_ makes the higher frequencies contain (non-mirrored!) copies of the lower frequencies. :-)

Oh yes you're correct, imaging would be the correct term for what's happening I think (aliasing is high -> low and imaging is low -> high)?