White Admiral or Red-spotted Purple — do those sound like the same butterfly? Well, they are, strangely enough. Although once considered separate species, they are in fact the same one that occurs from Alaska to Texas through-out the central and eastern U.S.
In the north they look like this, and are recognized as White Admirals.In the southern part of their range they look like this, and are recognized as Red-spotted Purples.
The other day, an individual that truly looked like an intermediate between these two forms showed up to have a drink from the milkweed flowers.
Wikipedia calls this species polytypic. This intermediate coloration seems appropriate for an individual that is somewhat in the middle of the entire geographic range where you would expect hybridization of the northern and southern color morphs.
The Red-spotted Purple form is actually a mimic of the poisonous Pipevine Swallowtail, so there may be advantages to keeping some of that southern coloration in this mid-latitude geographic area.