A Zebra Swallow Tail. He is having a drink from the moist sand. They are pretty common in the eastern side of the US.
Af 180 f2.8 ED with 11mm ext ring, hand held. Basic adjustments and crop.
I've only seen one in person once; I LOVE the red antennae and those bright patches of color on the wings. I think they're just gorgeous. Nice angle on this shot.