Similar species & differentiating characters:
O. synodica is a more western species and typically more yellow in color than orange.
Gerry Bunker, a well versed cicada specialist, provided the following commentary and information.
Okanagana balli is the only Okanagana species known to exist at the James Woodworth Prairie & is currently protected at this site in Illinois.
For more info on O. balli at the James Woodworth Prairie please refer to the following link.