I've never quite figured that story out. I hear them every year.........Maybe some areas have an over abundance of them periodically but they're there, year after year......
Personally, I love their sound. It signals an end to the hot summer and the harvesting of the fresh crops that will soon be showing up at the local roadside stands where I live.......
Another sound that nobody gives any notice to are crickets. The summer is silent because the adults lay their eggs in the fall and then the eggs hatch in early summer. Throughout the summer they continue to grow until they become full adults then start cricketing to attract a mate. They mate, they lay their eggs and the cold weather ultimately kills off the adults.......Then the cycle is repeated next summer.