Synchronous fireflies are a unique species that actually synchronize their light display.

Each year, countless lightning bugs converge upon the national park, flickering among the trees in one of the country’s most beautiful forest-scapes. Details regarding this year’s dates and how to get access (a limited number of people can attend) have just been released.

The Great Smoky Mountains National Park just announced the dates for its annual synchronous fireflies event, during which swarms of lightning bugs will light up the park at night. The once-a-year phenomenon is so popular that a lottery system has been established for obtaining the coveted parking passes required to attend.

This year, the event will take place from May 30 to June 6, and the lottery for the parking passes opens on April 26, 2019, at 8 a.m. EST and will close on April 29, 2019, at 8 p.m. EST. You can enter the lottery at

During the peak firefly display period, there will be a shuttle service from the Sugarlands Visitor Center, located at the northern tip of the Great Smoky Mountains National Park (which occupies portions of North Carolina and Tennessee). The shuttles will take passengers to the Elkmont viewing area, where the largest gathering of synchronous fireflies in the Western Hemisphere occurs. Visitors who wish to see these bright bugs put on their light display must acquire a parking pass for the Sugarlands Visitor Center and ride the shuttle to the viewing area.

The firefly display takes place in the Elkmont section of the Great Smoky Mountains National Park.
So, what are synchronous fireflies, exactly? They are a unique species of firefly (a type of beetle also known as a lighting bug) that can actually synchronize their flashing light displays. Their light patterns, which are produced in their “lanterns” along their abdomens, are part of a mating ritual that helps males and females recognize each other. The males will fly and flash their light and the typically stationary females will respond with a flash, according to the park’s dedicated synchronous fireflies page.

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No one is exactly sure why the fireflies flash their lights in unison, and they don’t always do so. When they do, a burst of light ends with an abrupt period of darkness.

Fireflies' bioluminescent lanterns are tucked into their abdomens.
The peak mating season lasts for approximately two weeks each year, and the dates of the display vary from one year to the next. Scientists predict the dates based on factors such as temperature and the moisture in the soil.

Even during the peak season, attendees aren’t guaranteed a perfect display, the park has cautioned. Environmental factors such as rainfall or cooler temperatures that fall below 50 degrees can shut down the display on any given night.

Nevertheless, those who would like to try their luck at having the rare chance to see the annual phenomenon will need to enter the lottery on April 26 at A total of 1,800 vehicle passes will be distributed for the eight-day event (or 225 per day): 1,768 regular parking passes (for vehicles up to 19 feet in length carrying a maximum of seven occupants), and 32 large vehicle passes (for buses and RVs ranging from 19 to 30 feet in length and carrying a maximum of 24 occupants).

Lottery applicants will be informed on Friday, May 10, as to whether they have obtained a vehicle pass. Each parking pass is valid only for a specified date, and an arrival time between 6:30 p.m. and 7:30 p.m. will be assigned. There will be a $25 vehicle fee charged upfront, and an additional $2 (cash only) per-person fee will be charged when boarding the shuttle to the viewing area. No additional passes beyond those assigned during the lottery will be made available.

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Attendees are asked to cover their flashlights with red or blue cellophane so that they don’t disrupt the viewing experience and to turn them off altogether when they have found a viewing spot. They are also asked to not catch the fireflies, so leave those Ball jars at home, folks!

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