Female Purple Emperor!

A much more knowledgeable friend than me has pointed out that the overwing of a female Purple Emperor is easily confused with the White Admiral. But the underwing is quite distinctive with its “eye”.

I had to look this one up, I'm not sure I've seen it before.  And I only got a glimpse of the top of its wings (extra) as it flew back to the treetops as soon as I opened the door.  The White Admiral is slightly larger than the Red Admiral, lives at the top of the trees in broadleaf woods, and lays its eggs on the non-flowering shoots of the honeysuckle, so that its caterpillars can eat the leaves.  I haven't spotted any caterpillars yet.  It was sheltering on the window in a rainstorm and was whisked away by the wind as soon as it took off.