Thousands of tourists flocked last month to one of Great Smoky Mountains National Parks most popular attractions: the spectacular mating displays of synchronous fireflies.
Photinus carolinus is one of at least 19 firefly species in the park, but the only one that blinks its yellow, bioluminescent lantern in time with others.
Distinctive flash patterns let fireflies of the same species identify each other. Synchronized flashes five to eight bursts of light every few seconds may help males compete for attention or females compare suitors.
The annual ritual continues for two weeks, its timing dictated in part by temperatures and soil moisture, and can include thousands of insects. Its so popular that the park sold all advance parking passes to the Elkmont viewing area in a single day; shuttle buses ran from June 6 to June 13.
Despite the acclaim, park scientists say the fireflies can also be found outside the park in woods with little understory growth and at the edge of moist, wooded areas.