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Hyla versicolor
Tree frog , pebbly skin, slit yellow gold eyes, 1 1/2-2 inches long
Outer edges of small town, mixed with central Illinois forest
Was attached to my glass door. Think it lives in the old tree (elm?) in my yard.
Well, there's actually no way to differentiate the species aside from their calls and DNA testing. They're physically identical, so it's impossible to tell which is which from just a picture.
I googled both and my guess would be H. Chrysoscelis, though my frog wasn't nearly as brightly patterned as the ones I saw pictures of.
Looks like it might be a gray tree frog, Hyla species (either H. versicolor or H. chrysoscelis). It's sort of tough to say from the picture though, due to the lighting.