The last of the field crickets are singing now, until frost stills them. I don't know which species they are -- I know we have several fall crickets, but I'm far away from my 'area of expertise'!
Here's a link to a fall field cricket song from the University of Florida. The magic of digital.
I love the seasonal waxing and waning of the nocturnal symphony of insect songs (and frogs, and birds, too). The symphony is at its peak in summer.