A quirk of nature, in a way: the 17 year cicada. Their nymphs remain underground, feeding off fluids from tree roots, until after 17 years, millions emerge all at once. They climb up the trees, molt and the fly up into the canopy. the males issue a continuous humming mating call. Given the sheer number of them, the sound can be incredibly loud. Some areas have them in abundance; other places not far away have hordes of them. We have none in the area of Berlin when I live, but when we went hiking in another section of town, he heard the characteristic hum and were able to find some. In Southington, a town next to ours, they are so loud as to be truly distracting.