Aberrant female Eastern Tiger Swallowtail - Papilio glaucus

one possibility, though not necessarily the correct one,

is perhaps that this is a gynandromorph, in which most of the insect is female, but that male characteristics are showing on the wings to varying degrees. In other words - part female, part male. I don't pretend to understand the cause, probably genetic and/or hormonal, but it happens occasionally in animals, particularly in arthropods, and is particularly obvious when the males look very different from the females.

It could also be not quite that extreme, but that genetic or chemical factor or process that controls expression of the black vs. yellow female forms during development got just a bit out of kilter, and some spotty patches of the yellow morph showed up on the wings because of it.

I suspect that it is a gynandromorhp though. If you have the specimen, and examine it, you may find some hints of male structures on the left side of the body as well. Here is a bilateral gynandromorph - same species - more extreme than yours (in which the male part is a bit more extensive than the female part) at Wikipedia.

Moved from ID Request.

… David J. Ferguson, 30 July, 2012 - 3:27pm

Maybe a "transitional morph"?

I've done a bit of research on my own now. I'm pretty sure it's not a gynandomorph, because it looks to be all female. I did find some references to a "transitional morph", but all the examples I've found so far are bilaterally symmetrical.
I did not collect the specimen--I don't have permits for Ohio State Parks, and it flew high into the trees after just a few photos.
I'll post a couple more photos, in case they help. One shows more of the individual's body, less obscured by its wings.

… Jay Cossey, 30 July, 2012 - 9:41pm

There are all shades between nearly black females

and yellow tiger-striped females, but when they are "normal" they don't have patches of mis-matched scales, they are just intermediate in overall coloring (and yes - symmetrical. The less of the dark scaling they have, the more of the stripe pattern that shows. This one is abnormal, but it's hard to be certain why. Maybe she just decided be a tad more flashy than most :0)

Here is one on BugGuide that is "normal", but about half way between the usual dark and light morphs.

… David J. Ferguson, 31 July, 2012 - 1:49pm

I think you're right!

I posted these shots on my Flickr account with the title "She's So Unusual" in reference to Cyndi Lauper. (Cyndi seems to like asymmetry and colorful streaks too.)

Here's my Flickr account, if you're ever bored... ;-)
http://www.flickr.com/photos/74102791@N05/

… Jay Cossey, 31 July, 2012 - 4:33pm