This butterfly was the size of my hand

I was in the back today discussing thin set mortar with Ellen when she spotted this huge butterfly by the flowers. We both went for our cameras. It hung around for a few minutes waiting for us to photograph it on the Phlox.
She said she gets really big butterflies like this at her house but does not know what they are.

I am working on a mosiac which I was going to do 2 years ago... finally am starting the bird pond. I've never done thin set mortar before. Lets see how it works. I cannot find my nips anywhere. I even straightened out the barn a little looking for them.