OK, so I did a tiny bit of research. I think it might be a Catocala parta (also known as Mother Underwing) and I think it might be a female. When it flew from the screen door to my very dusty picture window, it started vibrating...much to Matilda's delight. A chorus of tiny meows immediately followed the sighting.
Oh, I learned a new word pairing as a result of this sighting! One of the websites referred to the underside of the moth as verso. Thus I stumbled upon: recto & verso.
Recto: The right-hand page (or front side) of a book, manuscript, or codex
Verso: The left-hand page (or back side) of a book, manuscript, or codex
I love new words.