‘Magical’: synchronous fireflies light up US national parks

For two weeks in late spring, near dusk, the fireflies at the most-visited national park in the US flash in unison, a one-of-a-kind natural phenomenon'

As fireflies in the southern Appalachians search for their mates each year, a crowd of people awaits them, hoping to catch a glimpse of a rare light show known to some as a life-changing experience.

For two weeks in late spring, near dusk, the synchronous fireflies at the Great Smoky Mountains national park put on a spectacular display across the landscape, flashing in unison for about five seconds and then stopping, together, like twinkling Christmas lights.