Lighting up the night sky; synchronization of fireflies

BY Kelsey Davis
TDEC Sustainable Practices

Every year near the Elkmont Campground in the Great Smoky Mountains National Park, tens of thousands of a species of firefly, known as Photinus carolinus put on quite a show, lighting up the entire forest in a brilliant twinkling display. This year’s viewing dates were announced for May 30 through June 6.

The Smoky Mountains has the largest population of synchronous fireflies in the Western Hemisphere. There are a number of different firefly species in the park; however, this particular species is the only one capable of synchronizing their illumination patterns. Lightning bugs are a type of beetle. And like all beetles, they start out as larva.

They will spend the first year or two of their lives as larva underground feeding until maturity. Once mature, they emerge as lightning bugs ready to mate. This is the two week, spectacular viewing period that thousands of people come to see. The remarkable synchronized blinking is actually the males working very hard to attract a female.

The male fireflies hover two to seven feet above the ground while the females stay on the ground. A courageous male will begin flashing around 9:30 p.m., right at dusk, and after a few minutes the rest will coordinate their luminescent lanterns. The males flash for a period of two to four seconds, and then pause for an eight second break in which the females will respond with a quick double-flash. This synchronized biological light show will continue until midnight or later.

If one has never actually witnessed the event, sometimes upon envisioning the phenomenon, individuals will portray a pulsing glow of light that blinks on and off together at once. This, however, is not the case. Even though the males are flashing in the same time pattern, they are not all flashing together.

It is more similar to a spectacular Christmas light display of rapidly twinkling lights and then a sudden period of complete darkness, as if someone pulled the plug. Scientists speculate that the reason the males create a synchronized dark period is so that they can search for a willing mate without being distracted by other flashing males.
This amazing nature spectacle started becoming highly popular in 2005, and in 2006 through a partnership with the city of Gatlinburg. Shuttles were provided for the park to use during the eight-day viewing period.

Guests park at the Sugarlands Visitor Center and then take a short shuttle bus ride to the trailhead. The shuttle reduces traffic and congestion and also helps to protect the fireflies and reduce disturbance during the critical mating period.

Originally, the viewing period was first-come, first-serve, but because masses of people would stand in line for hours and hours, they changed to an online reservation system. The website system was not much better though, because it would crash due to the enormous surge of users and all the passes would be sold out in roughly 30 seconds after opening.
In 2016, they went to a lottery system on the National Park Service site. People have four days to apply at their leisure, and the winners are selected at random. This year out of the 18,486 applications for a one night lottery pass, only 1,800 were accepted.

Luckily, even though this is such a high-demand event, it is very affordable to attend. It only costs $2.75 per pass, and you are only charged if you are successful in receiving a pass. Likewise, the shuttle is only $1 per person to ride.

This may seem like only a select few get to see the fireflies. However, roughly 12,000 people get to witness the breeding show each year. Each lottery pass is awarded per vehicle, not per person. This includes 1,768 parking passes for standard sized vehicles with up to six passengers, and 32 large vehicle passes are permitted as well allowing a maximum of 24 occupants each.

Visitors can also come from the nearby Elkmont Campground, which has 220 campsites.
“Roughly 7,000 visitors come from the trolleys and about 5,000 from the campground. People migrate from all over the country to witness this once in a lifetime event,” said Dana Soehn from the Great Smoky Mountains National Park, “Last year, 42 different states were represented.”

You might be tempted to begin planning a viewing trip for next year, but you must plan carefully. The synchronized showing may happen each year, but the dates always vary. The fireflies may emerge any time between mid-May to mid-June and be gone in two weeks.

The dates of the firefly lottery are usually released sometime in late April. Scientists at the park predict the exact dates each year based on various factors including air temperature and soil temperature. However, this amazing sight is something that should be on everyone’s bucket list.