Hot, humid summer days may be a little tough on us, but butterflies seem to love them. I captured this shot of a spectacular Eastern Tiger Swallowtail (Papilio glaucus) this past weekend at Huntley Meadows Park as it sipped nectar from what I think is Joe-Pye weed (g. Eutrochium). (I am a bit uncertain about the plant identification and wonder if it might instead be a kind of milkweed, but “Joe Pye” rhymes with butterfly and sounds cooler, so I’ll go with that as a possible identification.)
Unlike many butterflies that I see at this time of the year whose wings are tattered and torn, this butterfly seemed to be in perfect condition. The sun was shining brightly when I took these shots and I was really afraid of blowing out the highlights of this lightly-c0lored butterfly. I switched the metering on my camera to spot metering and was able to get a good exposure of the butterfly and the background went really dark, adding a bit of drama to the images.
© Michael Q. Powell. All rights reserved.
Mike Powell 
I agree with your tentative ID of the Joe Pye weed. There are several varieties, and the one that grows along the little trout stream near our cabin in northern Minnesota has leaves with more serrate edges. And up there, especially the damselflies (primarily the river jewelwings) just love them!