Synchronous Fireflies of the Great Smoky Mountains

In the forests of the Smokies, after dark, an incredible rhythm appears. Thousands upon thousands of fireflies flash on their own, then, as if on cue, the whole valley lights up five or six times at once before falling into darkness together. They are one of the few fireflies in North America that synchronize their flashing, they appear for only two or three weeks a year, and you need to win a lottery to get in.