Moved from Oecanthus. While a definite species ID cannot be made on this female, she is definitely in the nigricornis group -- meaning she has dark antennae. My HUNCH is Forbes...but cannot be certain.

Without the antennal markings, it can't be definitely ID'd. However, the possibilities are: Black-horned, Four-spotted or Forbes' tree cricket. While this has no scientific basis, I noticed the distal portions of the antennae on this female APPEAR to have a brownish tint. I noticed a similar appearance on the Forbes' tree crickets I photographed this past summer. Forbes' are known to occur in Illinois. At this point in time, as far as I know, Forbes' can only be definitely ID'd by the pulses per second of the song of the males at known temperatures. (ie. 80 degrees = approximately 80 pulses per second / 60 degrees = approximately 60 pulses per second).