We had a big population of them a few years ago. The first time I encountered them was visiting my parents. Who lived up in the smokey mountains in N.C. It was deafening but actually were calming to fall asleep for me.These are Cicadas. The larvae stay dormant under ground for years, often 17 years, more or less. This Summer will be the next major bloom....17 year old grubs rise up, crawl up trees, shed their exoskeletons fly about & mate. They HUM day and night to attract one another to mate. They mate, crawl back down & deposit eggs....and come back in 17 years.....