I can't thank you enough for your time and your patience in trying to help me figure this one out! I've been looking through my books (Capinera's "Field Guide to Grasshoppers, Katydids, and Crickets", Himmelman's "Guide to Night-Singing Insects of the Northeast", and Elliott's "The Song of Insects") and through Bugguide's and SINA's photo and info pages. Unfortunately, I'm too ignorant to be able to truly see the features you've described. (To my untrained eyes, all of the pictures of vernalis look as if the pronotum is widened in the middle, and none of the pictures of rubens show red spots on the sides of the pronotum.) Please understand that I don't disagree with you, but that I need more guidance in order for the knowledge that you've shared to sink in. Can you recommend any additional books or websites that might help me? Can you point me toward photos that show the features you've described? Also, do you think that G. fultoni may be a possibility in addition to rubens and pennsylvanica? The range map in Capinera looks a little closer to my location than rubens. Again, thank you so much for trying to help me. I really appreciate it!

Absolutely - I recommend using the Alexander 1957 document describing the field crickets of the eastern United States. It's a bit outdated, but there is a handy dichotomous key at the end just before the references. It also has range maps and information about their songs.

The red spots may require some lighting to see. The other day I photographed some vernalis and never saw any red marks until I looked at the photo, which had a powerful flash that helped illuminate the red marks. This photo can be seen at its Wikipedia article that I pieced together shortly afterward.

As for pronotum width, you'll want to look from above, not from the side. Since there's no single characteristic that distinguishes any eastern species, it's common for them to get misidentified.

Another thing-- keep in mind that the author of that document indicates that female crickets do not necessarily follow the rules he set forth (I just noticed you've got a female there, not a male). I'd recommend searching for male crickets and run those through the key-- if there are no males of a species to match a female of the same species, it's likely I've misidentified it.

Thank you so much for sharing Alexander's paper and your vernalis photo! Your photo enabled me to see the red spots to look for on males, and Alexander's article (although a bit outdated) was full of fantastic information - I read it top to bottom! Looking Figure 8 of Alexander, the only species that would be at this stage of development at this date in my area are pennsylvanica and rubens. Pennsylvanica would be blacker, like the first photo below, and rubens would show more red, like the second photo. Mine must be rubens! I really appreciate your help, not only with this individual, but also for showing me what to look for in the future. Thanks!

Of course; I had actually just discovered this paper (and your photo of the vernalis) a few days ago while keying my own vernalis specimens. :)