Congaree National Park in South Carolina is a wealth of biodiversity, from 397 animal species to over 800 plant species. And, while there is no precise count of insect species within this park, it’s probably safe to say there are a lot of insects, including fireflies.
Photuris frontalis, Congaree National Park / Lynn Faust via NPS
There are three types of fireflies in North America that are synchronous, meaning they coordinate their little butt lights to blink in unison. Congaree focuses on the synchronous species Photuris frontalis. This park is so famous for this species that an annual event is held every year in May for visitors to watch these fireflies blinking in unison, lighting up the area with bright dots of light like little fairy lanterns. This event is so popular that in order to attend this nighttime sight, a lottery for event passes is held in April.
To look at a firefly, you would think they are an ordinary-looking insect. The magic happens when the landscape turns dark. But, what is a firefly (aka lightning bug), anyway?
Photuris frontalis is not a fly, but a beetle. The light it produces is called bioluminescence, where chemical reactions in an organism produce light. Fireflies are not the only creatures to produce this organic light. Jellyfish, plankton, squid, and fungus are a few other bioluminescent lifeforms. If you walk along a seashore at night, you can see the bioluminescence in the waves that lap up onto the beach.
Fireflies communicate with light – mainly to find a mate, but also to sound an alarm or warn off intruders. Why fireflies synchronize is not clear, although scientists studying fireflies have noticed female fireflies are more likely to respond to males fully in sync, rather than those males even slightly out of sync. The theory is that synchronization might be a means of species recognition between males and females.
Fireflies don’t really live very long – maybe one or two years. They spend most of that time within the soil as larvae. Once they emerge above ground, they live for 3-4 weeks with the goal of finding a mate with which to reproduce.
What about those poor fellas that blink out of sync?
According to park staff:
At first glance it may seem like all the fireflies you see are blinking in unison. While the fireflies you see at Congaree are synchronized, a closer look reveals that it is not a uniform synchronization. Researchers studying Photuris frontalis here at Congaree recently found that, rather than all fireflies being uniformly synchronized on the same tempo, some groups are on slightly different tempos others, making the fireflies as a whole collectively synchronized. This naturally occurring coexistence of both synchrony and asynchrony is known as a chimera state. Mathematicians and physicists in the past have only been able to observe this phenomenon in laboratories through carefully designed and controlled experiments, making the synchronization of fireflies at Congaree one of the only known observable natural occurrences of this phenomenon! You can read more about this research done at Congaree here!
Why is there a lottery to watch the fireflies at Congaree?
For many years the synchronous fireflies at Congaree were something only a few people each year came to see. Word spread, however, and by 2016 large numbers of people were coming to Congaree to see them. Concerns that this rapid increase in visitation would have negative long-term impacts on the synchronous fireflies and their habitat led the park to hold its first managed viewing event in 2017.
Between 2017 and 2019 an estimated 25,000-30,000 visitors came to see the synchronized fireflies. The pandemic in 2020 gave park staff the opportunity to observe and compare synchronous firefly activity in both the viewing area and nearby locations that had seen little to no event visitors over the past three years. The results of this work found that synchronous firefly activity had visibly decreased compared to neighboring locations, raising concerns that with visitation only likely to increase in the future, this trend would only get worse.
To better protect firefly habitat from further damage and reduce overcrowding in the viewing area, the park implemented a lottery system modeled after the one that Great Smoky Mountains National Park has been using for their annual synchronized firefly event. Started in 2021, this new system not only allows park staff to provide a more comfortable and enjoyable visitor experience, it is also helping to ensure that there will be fireflies for the future.
If you would like more information about this annual event, including how to enter the lottery for a vehicle pass, please see our Firefly Viewing Event page.
FYI, the 2025 Synchronized Firefly Viewing Event lottery has already passed, and the event itself will take place May 14-21. For those of you wishing to attend in 2026, click here.
Firefly fairy lights, Congaree National Park / NPS file
