When in the late summer early fall will the bugs pass?

Depends on the year. I know that doesn't help much, but last year there were reports of pretty bad mosquitoes well into September, which is pretty unusual. Generally in mid to late August the skeeters start to thin out, and by September they're not a problem, but there are always exceptions, like last year.

All it takes is rain and warm temperatures. Usually late summer /fall is dry, but not always!