Every year, for two weeks in June, thousands of people flock to Elkmont, a small trailhead in Great Smoky Mountains National Park in Tennessee, to observe a very rare firefly mating ritual. In fact, it is one of only two places in the world where fireflies conduct a synchronized mating dance. But before planning your trip to Tennessee, check out the fireflies in action and see if it's worth the trip. To discuss insect tourism or firefly mating, use the hashtag FireflyDance on Twitter.