The Magic - And Science - Of Synchronous Firefly Displays

This episode delves into the fascinating world of fireflies, particularly focusing on the phenomenon of synchronous firefly displays.

1. Synchronous fireflies are a rare phenomenon where thousands of fireflies flash in unison, creating a mesmerizing display.
2. The adult life stage of fireflies is incredibly brief, often lasting just a few weeks, making timely observation crucial.
3. Habitat destruction and light pollution are significant threats to firefly populations.
4. Fireflies are indicators of environmental health, and their decline signals broader ecological issues.
5. Listeners can contribute to firefly conservation through habitat preservation and reducing light pollution.

1: Introduction

Regina Barber sets the scene with a personal anecdote of observing fireflies, introducing the episode's focus on their magical displays.
Regina Barber: "It feels like a fairy tale...it was the magic time of summer in and around Washington, DC."

2: The Science of Fireflies

Discussion on the lifecycle of fireflies and the environmental conditions crucial for their survival.
Ping Huang: "Fireflies are beetles, so they got that four-part lifecycle."

3: Synchronous Displays

Exploration of synchronous fireflies at Congaree and the Great Smoky Mountains, including differences in their flashing patterns.
Lynn Frierson Faust: "Carolinus do this explosion of flashes for 3 seconds, and then the whole forest goes dark for 6 seconds."

4: Conservation Efforts

Insights into the challenges facing fireflies and measures to protect them, like reducing visitor impact and controlling predators.
Ping Huang: "The park started limiting the number of visitors after they realized that overcrowding was disturbing the fireflies."

1. Create a Firefly-Friendly Habitat: Maintain native plants and shrubs, and avoid using broad-spectrum insecticides.
2. Reduce Light Pollution: Use motion detectors for outdoor lights to minimize impact on firefly mating signals.
3. Support Local Conservation Projects: Participate in community science projects like the Firefly Atlas to help gather crucial data.
4. Educate Others: Share knowledge about fireflies and their ecological importance to promote broader community involvement.

Every year for two weeks between mid-May and mid-June, Congaree National Park in South Carolina is home to a fairy-tale-like display of flashing lights. These rhythmic performances happen all because of thousands of fireflies, flashing their belly lanterns at exactly the same time. According to the National Park Service, there are just three types of these synchronous fireflies in North America, making the experience all the more magical for the lucky visitors who get the chance to see them.

Firefly scientists and enthusiasts hope these displays in places like Congaree will inspire people to care about other kinds of fireflies, also known as lightning bugs, in the U.S., which are not as well-studied – or well-protected – as synchronous ones. Some community scientists are already taking on this mission with projects like the Firefly Atlas, where volunteers can help survey for fireflies and report sightings.

People

• Regina Barber, Ping Huang, Lynn Frierson Faust, Orit Peleg, Sarah Lewis

Companies

• None

Books

• Firefly Field Guide to the eastern and central US and Canada

Guest Name(s):

• None

Content Warnings:

• None

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Regina Barber
You're listening to short wave from NPR.

Hey, short waivers. Regina Barber here. And a few weeks ago, I went on a wild nighttime ride. We're in this like cart that this lady is biking us around with a dog and we're looking for bugs.

Friend of the show and wonderful, beloved reporter Ping Huang was there.

Ping Huang
We are loaded up here in the cargo wagon.

Regina Barber
Cargo bike, cargo bike. And we are very tightly pushed in. And ping is a patient, patient woman.

And she has a dog on one side of her, me smushing her on the other side.

Ping Huang
It was a tight fit.

Regina Barber
It was. I felt terrible pain because you had organized this trip to see something very specific and very special.

Ping Huang
It's true, Gina. We were out on a bike trail at 09:00 p.m. on a weekday for a reason.

And even though there were cars zooming past us, planes flying overhead, the conditions were actually totally perfect.

Regina Barber
They are magical. Like I'm looking out into the marsh and I'm seeing all these like the darkness and bushes, and then you just see like pops of light.

It feels like a fairy tale. I keep on saying Disneyland, but it really, yeah, it was the magic time of summer in and around Washington, DC.

Ping Huang
When you can see fireflies, hundreds of them, thousands of them, blinking their belly lanterns on and off, so long as you know where to look.

Regina Barber
Today on the show, the brief and wondrous adult lives of fireflies. We'll take you on a trip down the east coast to see some special.

Ping Huang
Species, and we'll talk about why some are endangered and how you can help.

Regina Barber
You're listening to short wave, the science podcast from NPrdem.

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Regina Barber
Okay, so, a few weeks ago, on a hot, humid night, we saw an incredible Firefly show, aka Lightning bug show. And seriously, ping, it was this random little patch of dense forest, like, sandwiched in between the airport and the parkway.

Ping Huang
Right? That little protected marsh between the bike path and the Potomac river was actually the perfect habitat for some fireflies. So there's a lot of different species, but what they all seem to have in common is a love for warm, humid environments. Maybe some tall grass and definitely some standing water. Seriously, one of the big enemies of fireflies is drought.

Regina Barber
So why is water so important to fireflies?

Ping Huang
Well, I say it's the water and the dirt, and both of these are important to their life cycles. So fireflies are beetles, and so they got that four part lifecycle. They start as eggs, then they hatch as larva. And the larval stage is actually where they spend most of their lives. They can spend up to one to two years crawling around underground, eating other invertebrates, and then they burrow down, generally into the ground. This is called their pupil stage, and it can last a couple of weeks. And this is where they really transform themselves. Then they emerge as full adults, and that's when people like us walking around at night can see them flying around and flashing in fields and trees.

I spoke with Lynn Frierson Faust. She's author of a Firefly Field Guide to the eastern and central US and Canada. And she says that adult stage is relatively brief.

Lynn Frierson Faust
A lot of these species, many of them, they flash 20 minutes a night, and that's it.

And they only live two weeks. So if you're not standing in the right place at the right time, looking the right direction, you'll miss him.

Regina Barber
Yeah. I mean, it was a brilliant light show that we saw a few weeks ago, and we caught the tail end of this year's peak of fireflies in northern Virginia.

Ping Huang
Right, right. And right now, it doesn't look like that anymore. And when the fireflies peak, depends a lot on how hot and humid it's been in the weeks and months just before it.

Regina Barber
Okay. Ping. So those weren't the only fireflies you saw this summer, though, right? I know you're dying to tell me more.

Ping Huang
Yes, absolutely. So you're right. Earlier in the season, I actually went on a trip looking for fireflies down at Congery National park, which is near Columbia, South Carolina. This was back in May, since further south, where it's hotter and humid, the fireflies came out earlier, and I went to see a specific behavioral phenomenon, synchronous fireflies. These are hundreds, thousands of fireflies that are all coordinating across a large expanse of nature. So they're blinking all at the same time.

Regina Barber
Oh, that sounds really, really cool. Can you only see them in South Carolina?

Ping Huang
Okay, well, they're rare, but they're not that rare. So there's just a few species of synchronous fireflies in the US. Conga, where I went, has one kind, and the great Smoky mountains in east Tennessee has another.

Lynn Frierson Fest has seen both kinds.

Lynn Frierson Faust
What the great Smoky Mountains National park has is fotinus carolinus.

That is completely different from what is here at congre is faturis frontalis. Different genus, different everything.

Ping Huang
She says that even the way that they flash is different.

Lynn Frierson Faust
Carolinus do this explosion of flashes for 3 seconds, and then the whole forest goes dark for 6 seconds. The congery synchrony is constant.

Like that.

Regina Barber
Weird.

Ping Huang
Yeah. And Regina, that's exactly what I saw when it got dark, like really dark in the forest, I started seeing these little flashes in the trees. At first it was like a couple of them blinking randomly. And then as more and more of them joined in, I started to see this pattern emerging, like a rolling wave of lights.

And then at some point, they synced up perfectly, at least to my human eye. And they were all flashing at once. And that was a pattern that they kept up for a little while before it just sort of went back through the cycle all over again.

Regina Barber
It makes me think of those, like, drone fireworks.

Ping Huang
I mean, it did look like Led lights a little bit.

Regina Barber
Yeah. How are they coordinating, though? Like, how are they doing this?

Ping Huang
Well, that's still kind of a mystery, something researchers are trying to figure out. So when I was down at Congaree, I met up with Orit Peleg. She's a computer scientist and biophysicist at the university of Colorado in Boulder. And Orit had come to the Congaree with some folks in her lab to study how this Firefly synchrony works. She says that there does seem to be this evolutionary advantage to having a whole swarm of firefly flies blinking at the same time. It boosts their signal, makes them more visible to their mates down on the ground.

Orit Peleg
And we're trying to understand how they manage to do it. They're very small creatures. They have limited visual perception, and they certainly cannot communicate directly with all the other fireflies in the swarm. But somehow, just by communicating with a small group that are near to them, they're able to create global synchronization, which is just a feat of animal behavior, I think.

Ping Huang
Arit says that visual cues are a big part of it. And she says they know this because they can actually get fireflies to flash and sync with led lights.

Regina Barber
Wow.

Ping Huang
When the fireflies get closer, they also communicate with chemicals, pheromones, too. But what's really cool about this is that there doesn't seem to be one leader in the pack. Areet has taken videos from within and around these flashing swarms. She's slowed them down, and she says that it seems like it can really originate from all kinds of different places in the pack.

Regina Barber
This is, like, fascinating, but it also sounds, like, really magical to witness.

Ping Huang
It was. It was completely magical for me, beautiful. But as Lynn says, the fireflies aren't actually doing it for our benefit.

Lynn Frierson Faust
I'm sure they have just a few minutes each night to find a mate, and sometimes it's as many as 100 males to one female. You know, we think it's beautiful and we love looking at it, but for them, it's life and death.

If they don't get those eggs in the ground for the next generation, they're done.

Ping Huang
Now, unlike some other firefly species, the synchronous fireflies at congery are actually doing pretty well. The park started limiting the number of visitors after they realized that overcrowding was disturbing the fireflies. And they've also been culling feral hogs who root around in the dirt and destroy Firefly eggs.

Regina Barber
Wow. Okay, so these are well known, well studied fireflies protected by the park. Are there firefly populations that aren't so lucky?

Ping Huang
Yes, most of them, I would say. So for some context. I called up Sarah Lewis, who's a professor emerita at Tufts University, and she studied fireflies for many years, and now she's actually focused on conserving them. Now, Sarah Lewis says that all the fireflies I saw this summer are the fireflies that are doing okay. I was telling her about this, like, droopy, swoopy Firefly I've been seeing in DC. And she was like, oh, yeah, that's the big dipper Firefly.

Sarah Lewis
It's an urban firefly, and it doesn't really care about light pollution.

We think one of the reasons for that is because it flies at just at sunset, where it's really actually still quite light out. And so it does fine. Under street lights, no problem.

Ping Huang
Now, Sarah says that out of the 170 or so Firefly species that are in the US, about one third fall into this category. Well studied, doing fine.

Sarah Lewis
On the other hand, there's about 10% of us fireflies that are not doing so well that are some degree of threatened with extinction.

Regina Barber
Okay, so 30% are fine, 10% are not. What about this other 60%? About.

Ping Huang
Yes. Math. Well, Sarah says there are just huge gaps in our knowledge on these other fireflies because the research is really time intensive and it's not well funded. Now, there is a movement to get community scientists involved. Sarah and some others have launched a project called Firefly Atlas. It's enlisting volunteers to go out and survey for 13 specific firefly species that are considered data deficient.

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Wow.

Regina Barber
Okay, so you can just go collect data for this project.

Ping Huang
Well, you do have to register, and then you also have to watch this hour long training video that tells you what data to collect.

Regina Barber
Okay.

Ping Huang
And then you go out at night to look for them.

Regina Barber
So, for the fireflies that aren't doing so well, do researchers know why?

Ping Huang
So Sarah says that there's two things in particular. Habitat destruction and light pollution. And that habitat destruction can come from human development or natural disasters and droughts. And it can hit some fireflies particularly badly because there are certain species that really need the specific conditions in, like, a cypress swamp or a freshwater wetland to survive.

And then there's light pollution.

Sarah Lewis
They use bioluminescent signals against a background of what used to be dark.

And as we light up more and more of the night, it makes it very hard for these flashing fireflies to be able to see each other and to be able to find mates.

Regina Barber
Okay, so this sounds like big environmental issues. Is there anything I could, like me, I can do to help? Aside from, like, helping the scientists collect data? Like, I love these fireflies, especially the ones we saw, and I want to keep them going.

Ping Huang
Yeah. So, Regina, if you're in a place where fireflies can live and you have a backyard or a front strip or you're responsible for a patch of nature somewhere, you can help to make it a good firefly habitat. Sarah says that this means having shrubs, native plants, and really, critically, not spraying your lawn with broad spectrum insecticides, which can kill fireflies, too. You know, another thing you can do to help is to leave some leaf litter around, make it a place where firefly larvae and the things that they eat can thrive. And you can also, of course, cut down on light pollution in your home or in your environment. So you can, you know, switch off the outdoor lights, use motion detectors so they're not constantly on anything really to help these burgers grow to adults and find their mates so that their cycles can continue on.

Regina Barber
I'm so excited. I'm doing everything right.

Thank you so much for this reporting.

Ping Huang
Pingdeen thanks for coming with. It's been so much fun.

Regina Barber
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This episode was produced by Rachel Carlson. It was edited by Burleigh McCoy and fact checked by Pinkenhouse. Kwesi Lee was the audio engineer. Special thanks to our local tour guides, Cameron Taylor, Josephine Liu and Judd Isbel. With friends of the Mount Vernon Trail, I'm Regina Barber. Thank you for listening to short Wave from NPR.

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