One of my favorite childhood summertime memories is watching fireflies in the evenings. After many firefly-free years, I got to see them again last weekend. Discover why they’re so cool and how they do what they do.
A few resources for your enjoyment:
Fireflies: how and why they light up
Insider Science: what’s behind the firefly’s glow? (YouTube)
Watch: fireflies glowing in sync to attract mates (YouTube)
Let it glow: fireflies illuminating Japanese woodlands — in pictures (The Guardian)
Music: Jens East — Daybreak (ft. Henk) www.soundcloud.com/jenseast
Licence: Creative Commons Attribution V4.0
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Transcription (remember, this is a direct transcription of what I said and is not actually how I write!):
Welcome to 9 Minutes of Wonder. I’m Betsy Hedberg. I hope this podcast will help you rekindle your sense of wonder for this awe-inspiring world. If you like what you hear in the next few minutes, please subscribe and share.
Last weekend, I went on a firefly walk at night, and it was really pretty cool because it was in this very small parcel of land that is between the Porto train station — and this is a major city in Portugal, so one of the main train stations there — and a major highway. It was this little farm that has some trees, and we went out at a time when the fireflies were just coming out, and, you know, it was magical.
So today I’m going to talk about fireflies because we all know they’re really cool, and maybe you’ll learn a few things about them.
Did you know that there are more than 2,000 species of fireflies in the world, and they live on every continent except Antarctica? They like to live in moist areas, so not deserts and not super-dry places. They often live in grassy areas or near bodies of water. So you can see them in certain places, but even if you’re in a place where there are fireflies, you don’t have to go very far for them to be no fireflies because they’re kind of picky. I learned that on Sunday. They’re a little picky about the habitat that they live in.
Another thing I learned: if your garden has the right habitat for fireflies, another interesting thing to know is that their larvae eat snails and slugs, so that could be helpful in your garden. The proprietors of this land said that is how they discovered that they had a viable firefly habitat. They had too many snails and slugs in their garden, and they were throwing them into one side of the garden, and that’s where the fireflies started to hatch and then light up.
But they only light up for three to four weeks after they’ve spent one to two years as larvae. So, like many insects, they have a really short life. When you see them flashing, they’re at the very end of their life.
Now, probably more interesting is the question of why and how do they flash?
Why do they flash? The main reason seems to be to attract mates. Not really surprising, is it? When you see fireflies floating around in the air in the evening and flashing lights, those are the boys, and the girls live, or the girls spend time, down in the ground, and they flash lights too, but they don’t like to fly. They have wings, but for whatever reason, they don’t fly. They don’t use the wings.
Another reason they flash is probably to warn predators that they taste bad, although some frogs love to eat them anyway, and I learned that fireflies will often keep glowing even after they’ve been eaten by a frog, so that the frog’s stomach will light up.
Every species of firefly has its own pattern of flashing, so that the males and females can tell that they’re in the same species and that they want to mate together. But some of the girls are sneaky, and they will imitate the patterns of other firefly species, so the males will come to them and say, “Oh yeah, hello!” and then will get eaten by the girl.
Now, this question of how do they make the light? Good question. This is an example — an awesome, incredible example of this awesome, incredible phenomenon in nature called bioluminescence, where living beings light up. Fireflies have special light organs at the bottom of their abdomens, and there are two chemicals in their bodies that combine with oxygen, and then there’s another special chemical that gets involved in this area of their body, and this all produces the light. The light would shine through this transparent part of their abdomen, so it’s a chemical reaction that’s causing the light.
One of the coolest things about fireflies is that some species of fireflies will synchronize their lighting, and you may have heard about this. There’s one species in the Great Smoky Mountains National Park, and in an area of that national park in eastern Tennessee, you can go see those fireflies not only light up at night on certain summer nights, but synchronize, so that after a while all of the fireflies are flashing in unison, or near unison. I think that would be so cool to go see, don’t you? And you can find some interesting videos and pictures of it, but you have to enter a lottery to go see them, because it got really popular and so they had to control the number of people who could go.
Scientists aren’t positive why they synchronize, but many people think it’s to help them attract mates, because when they’re all flashing together, then all of them appear brighter, and then the girls sitting on the ground can know, “Yeah, this is where the guys are.”
I also read one time about somebody visiting a guest house or hotel in southeast Asia, I don’t remember what country they were in, but they were just lying in bed at night looking at the ceiling, and they started to see fireflies on the ceiling of their hotel room. And the fireflies were lighting up together, and I would love to go see that.
Your favorite dinosaur may have seen fireflies too. They found fossils in amber that date back to the dinosaur era at least a hundred million years ago, and they found one I was reading about that it’s hard to tell it was a firefly, but then they were able to find the little light organ on its abdomen that was well enough preserved when they looked really closely at it.
As you can imagine, fireflies also turn up in various mythologies and legends. In Japan, they can be considered messengers of the gods, and they can be symbols of both love and of war, which I think is interesting. In China, fireflies often represent good fortune and prosperity. In Mexico, they often represent souls of the dead. And in European folklore, they’re typically good luck, but in some African folklore, they’re bad omens of disease and death, or messengers between the living and the dead, and in some African cultures, fireflies have healing properties and are used in traditional medicine. Obviously, Africa is a huge continent, so it varies across the continent.
If you don’t have the opportunity to see fireflies, I’ll share one or two videos where you can go — you know, it’s not as good, but you can go see what it might be like. Of course, as always, I encourage you to sit back and, you know, not be distracted, not do anything else, and just soak in how cool it is and how wonder-inspiring these little creatures are.
By the way, I didn’t mention they’re beetles. They’re not flies, but they’re flying beetles.
And if you do go see fireflies in real life, please don’t have your flashlight on, or just point it down at the ground until you get to a place where you don’t need it, because they don’t like any extra light, and light pollution is actually a really major problem for fireflies around the world. It messes up their lighting rhythm and prevents them from finding their mates, and this is actually a threat to their populations.
When we took our firefly hike, we did not use flashlights at all. It wasn’t a full moon or anything, but it was interesting how much we were able to see. They gave us walking sticks so we wouldn’t trip, because it was also kind of steep sometimes. They also asked us to keep our voices low because they said that if the fireflies — I guess they hear us. I didn’t research, you know, if they’ve got ears, but anyway, if the fireflies become bothered by our voices, then they will fly elsewhere, and then we won’t get to see them anymore.
So enjoy fireflies while you can. Their populations are declining around the world, again because of light pollution, but also habitat loss and environmental toxins and some other reasons. Sorry to end on a kind of a down note, but the place where I saw them last Sunday is scheduled to be destroyed to make room for luxury homes and a luxury hotel, which will all be next to a new high-speed rail line that’s eventually going to be built. So that may be the last time I ever get to see fireflies in that location.
Enjoy them now if you can, and I’ll talk to you next time.