It's a huge butterfly, nearly the size of my hand.
Edit: And a few minutes, later, on the same lantana, a tiger swallowtail, also enormous and...defective. A good chunk of his right side lower wing, including the swallowtail bit was missing. This did not seem to be slowing him up much--he took to the air several times, circling the yard, before returning to the lantana.
It would be wrong to be happy to see an injured butterfly, and yet, I can't escape the feeling of normalcy that the sight of defective-but-functioning wildlife evokes in me.