After 17 years of living and feeding underground, billions of Brood II periodical cicadas have emerged and are filling the air with the strange sound of their mating calls. Male cicadas use drum-like structures on their abdomen called tymbals to create a loud, high-pitched buzz to attract female companions, who respond with a quick flick of their wings together. This mating call and response, which sounds to some like the whining of electrical wires rising and falling, can reach over 90 decibels.

Within a short period of time, the cicadas will mate, and the females will bury their eggs underground before dying. Cicadas don't bite, but if the noise bothers you when you're outdoors, wear hearing protectors, such as earplugs or earmuffs.