Unexplainable - The man who walked butterflies on a leash

Episode Date: May 19, 2025

Static electricity plays an invisible role in the natural world, and it may even help insects pollinate plants. To understand this hidden force, scientists have jumped through some pretty weird experimental hoops — and “walked” butterflies through literal hoops. Guests: Sam England, postdoctoral researcher at Berlin's National History Museum; Benji Jones, Vox's environmental correspondent To read more about this experiment, Benji recommends this great article from Quanta Magazine, where he first encountered Sam's work. For show transcripts, go to ⁠⁠⁠⁠vox.com/unxtranscripts⁠⁠⁠⁠ For more, go to ⁠⁠⁠⁠vox.com/unexplainable⁠⁠⁠⁠ And please email us! ⁠⁠[e-mail]⁠⁠ We read every email. Support Unexplainable (and get ad-free episodes) by becoming a Vox Member today: ⁠⁠⁠⁠vox.com/members⁠ Help us plan for the future of Unexplainable by filling out a brief survey: ⁠⁠⁠⁠voxmedia.com/survey⁠⁠⁠⁠. Thank you! Learn more about your ad choices. Visit podcastchoices.com/adchoices

Hey, I'm Matt Bouchelle, comedian, writer, and floating head you may or may not have seen on your FYP. And I'm starting a brand new podcast. Wait, don't swipe away. It's called That Sounds Like a Lot. You know that feeling when you check your phone, read a few headlines and think, That sounds like a lot. I can't do this. Well, I can, and I'm going to get into it every Friday.

You can watch on YouTube or listen wherever you get your podcast. I'm going to start by breaking down whatever insanity is happening in the world. And then I'll sit down with a comedian or actor or writer or, honestly, anyone who responds to my DMs. This is not the place to get the news, but it is a place to get the news. but it is a place to feel a little bit better about it. That sounds like a lot coming May 1st, part of the Vox Media Podcast Network. All right, Benji Jones, my favorite biodiversity reporter. Hi, Bird.

Hello. You have a story for me. I do. I want to tell you about this guy I came across who has tied little leashes to butterflies and moths, like little leashes out of fishing line, and taking them for walks around his lab. And by walks, I mean little tiny flight. So, like, imagine a dude with, like, a real-life kite on the other end is a butterfly,

and he's, like, walking it around a room. This is so classic Benji. Okay. Why is he doing this, Benji? Yeah, I get that this research seems kind of ridiculous. But he's doing this strange, very odd research because he thinks it'll help us understand something that's actually pretty fundamental about how the insect world works. and more specifically about how insects might be interacting with a part of the world that's totally invisible to humans.

All right, Benji. I'm hooked. I'm compelled. I will follow where you lead. Where do you want to start? Let's start with this guy, Sam England. He's a sensory ecologist, meaning he, like, studies the way that insects sense their environment. And actually, when I... Cool job. Very cool job. And when I reached him, he was working on a project where he was studying spider vision and was, like, putting spiders on a little treadmill in, like, a virtual reality environment to understand how they respond to different stimuli.

So it was, yeah, crazy job. We're in the wrong job, Benji. I know, completely. Like, I want to be playing with spiders. But, yeah, butterflies on leashes. So for his Ph.D., he was studying how static electricity affects. the insect world. So static electricity, this is basically the buildup of electric charges. So, like, when I rub a balloon, right, or like when I shuffle around on a carpet and get a shot

because I touch something, right? That's static electricity. No, that's exactly right. So, like, we notice static electricity in these small ways, right? Like, getting shocks here and there. I also think about, like, when you open a package and there's a bunch of styrofoam pellets and they like cling to your body. That's also about static electricity. And so this is what Sam is investigating just in insects. It's quite a funny thing to try to measure the static charge on an animal. There's not a whole load of people that want to do this.

Why did he want to do this? So basically, there's been some work that suggests that insects might be using static electricity in a bunch of these invisible ways. and one way would be pollination. So if we go back for a second to the static electricity thing where packing peanuts are flying towards you and sticking to you and you open a package, what's happening there is that static electricity

involves a buildup of charge. So like you and the packing peanuts, one of you is slightly positively charged, one is slightly negatively charged, and so the peanuts are attracted to you. Sure. And so this might actually be happening with pollination too. But instead of peanuts and people,

you have pollen and insects. Okay. So pollen on flowers seems to have, at least in some cases, a slightly negative charge. And so what Sam wanted to figure out is whether butterflies and moths, these incredibly important pollinators, potentially are positively charged. And if they are, that could mean that pollen is not just like brushing up against their bodies and sticking to them, but actually like flying through the air when they get close enough to a flower, just like.

like the tiny packing peanuts are flying towards your body as you open up whatever your exciting packages. And if you find out that they are positively charged and this interaction is occurring, this could like open up this whole other dimension to pollination, to this thing that is really important to nature and to how we get our food. But to figure out if this is happening, Sam had to find a way to measure the charge on butterflies. There's not really any kind of of like pre-packaged equipment that you can just buy off, you know, Amazon or wherever to measure the static charge of an animal. So a lot of our stuff had to be built bespokely. Which is what led him to turning butterflies into like these little living kites in his lab.

Basically, Sam thought that insects might be picking up positive charges when they're flying around. Like, that's how they charge up. Like, the friction of their wings against the air might be like the equivalent to us scooting along the carpet and then like touching the doorknob and getting a shock. So building up charge. And so he needed to get these moths and butterflies to fly around. Okay. And then after he flew them,

he also needed to find a way to measure whether they'd become charged. For this study, we relied really heavily on a bit of equipment called a pico ameter. Imagine like a kind of a metal loop. And the idea is that the electrical charge of what passes through the loop can be measured. And so his task, his challenge, where the leash comes in,

is that he needed to get the butterflies and the moths through that loop. Wait, wait, wait. So it's not just that he's walking his butterflies around his lab on a leash. It's literally having them fly through little loops, like a tiny butterfly circus? It's very dog show vibes. Logistically? is this like, it sounds both simple and also when I try to imagine attaching a little leash to a butterfly.

Like how? Okay, yeah. How is he doing this? Okay, so basically two approaches. With some of the species, this was actually quite easy. What I could do was I could basically put the butterfly in a box and we lined this box with leaves so that the butterflies and moss were only making contact with a, a material that they would contact in their natural ecology, i.e. a leaf, you know, is they're flying around landing on leaves, landing on flowers. So we should get an ecologically

relevant measurement of their charge. So for some of the species, we basically placed the butterfly in a box and we left a tiny hole big enough for the butterfly or moth to fly out of. And a lot of butterflies and moths just like to go towards light. And essentially, when the butterfly emerged from the box, we could have this concentric ring sensor, mounted near the hole in that box and the butterfly would fly straight through the loop and we would get a measurement of that butterfly or moths charge. That's like the simple version if you can get the butterflies to fly out of the box through this loop. A lot of butterflies and moths were not cooperative. So for the butterflies and moths that

wouldn't fly out on their own, he basically had to get them to fly. We actually had to basically tie tiny lassoos made from fishing line around their abdomen. So we could tie a slip knot of fishing line around the abdomen of these butterflies and moths, which is completely removable afterwards. And some people, not me, had a much better aptitude for doing it. I must admit that I had this one colleague, Tom Neal, that I would come and bother every few days and say, I've got a few more moths and butterflies for you, a lasu for me.

Does it hurt the butterflies? No, it's a good question. Like, there's really no way to know definitively, but Sam said probably not, and the butterflies seemed fine after his study, and he'd often release them back into the wild. And he also mentioned that, like, to do this, he would knock out the butterflies using CO2.

It would, like, temporarily, like, knock them out, and then a few minutes later, they would wake up, and then to get them to fly, he just had to, like, kind of pull up the leash so they were dangling. And when butterflies are dangling and don't have their feet on the ground, they just instinctively start flapping their wings because they're like, oh, God, I'm in the air, I need to be flying.

And so the butterflies would start flying. And it's quite fun because once they start flying, you're basically walking them around, like taking a dog for a walk. And it was even more, I don't know what the word would even be, surreal probably. Like, sometimes it felt like a bit of a fever dream, especially given that my background is in physics and I never really imagined that I would be taking butterflies for a walk,

but I used to kind of fly them around the lab on their leash. And the lab that I worked in at the time had a huge glass front to one side of the lab. And this glass front faced straight onto the main corridor that most of the undergraduate students would walk along to get to the library. So very regularly I was walking or flying these butterflies around the lab, and undergrads would stare through the window at me and probably think what on earth is happening in there? But yeah, definitely probably came across like a bit of a mad scientist.

The ultimate goal is to get them to go through this loop to measure their charge, but he wanted to give them enough time to fly a little bit so that they would be picking up a charge like they would in the wild when they're flying from flower to flower. And so he flew them around the lab for a minimum of 30 seconds, and then his goal is to get them to stop flying so that he can just drop them through the loop. So in some cases, they would not stop flying.

They're really, like, tenacious flyers, really persistent flyers. And so what he would do is he would actually play the sound, the ultrasonic sound of bats. And bats are predators for a lot of moths. And so these moths would instinctively stop flying when they heard the sound of bats as, like, as a way to, like, immediately dodge an incoming bat. And so it's like a defense mechanism. Exactly. They'd freeze in the air, stop flying. And then they'd be dangling on this leash, and then he could put the leash through the loop and measure the charge of the butterflies.

Okay. So the maz, the butterflies, they like freeze, they fall through this little loop. It measures their charge. What did he find? Like, did he find that they were charged or not? Oh, I will tell you all about it after the break. Break? It's going to be after that.

Here comes a break. I'll tell you after the break. I'm screaming. I'm screaming. Break, break for break, break, break. It's the break. Flap those wings and wait till the break is over. Oh, is that funny?

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Tough. Every week I'm sitting down with trailblazing women at the top of their game to discuss ambition, work ethic, and the ups and downs that come on the path to achieving greatness. We'll dive into their stories and get valuable insights from top executives, actors, entrepreneurs, and other individuals who have inspired me so much in my own journey. Follow pretty tough wherever you get your podcasts. So, before the break, Sam was flying butterflies around and pulling them through hoops to see if they were charged up. What did he find? The short answer is that they, on average, were probably,

positively charged. So, like, what he was hypothesizing that these are positively charged turned out to be true on the whole. Like, some, there was a lot of variation. He said some were, like, a little bit negative, but in general, he saw positive charges. To be clear, these are not, like, massive charges that, like, if you touched the butterfly, you're going to get a shock. These are, like, very, very subtle positive charges. But the key here is that the difference between the butterfly and the pollen, according to these models that he made, is enough to cause pollen to be attracted to their bodies and jump through space. Of course, often when insects visit flowers,

they will actually just make contact with the pollen. So probably that's still the main mechanism by which pollen is attached onto pollinators is through physical contact. But what our study shows is that it's not necessary. And even animals that only very, briefly hover by a flower may still be able to attract pollen onto their bodies and then subsequently take that pollen to another flower and pollinate that flower. Wow. So are they, does that mean that butterflies and maws and maybe other insects are like potentially experiencing

like tiny electric shocks like every time they interact with pollen? Yeah, I asked him that question and And he said, no. It's not high enough for that. It really, it's quite a small charge. He said, like, they're not getting shocked every time they get near a flower. Because if they were, it's likely that, like, this would not be beneficial and, like, would be evolved out or, like, adapted away or whatever. But he said that it's likely that pollen can jump, like, several millimeters, if not, like, a

centimeter or more, depending on how positively charged the butterfly is. So, like, if you did look really closely at the interaction between a butterfly and the flower, you might see pollen move through space, almost like a magnet that you throw on to a fridge or something like that. I'm tossing my magnets from my refrigerator. I know. When I wrote that, I'm like, oh, that's a great analogy. And I'm like, in what situation are you like, do you have a centimeter between you and the magnet and the fridge? But it's like you casually walked by your refrigerator about a millimeter away and had a magnet and it flung to the fridge.

Okay, we're canceling the magnet analogy. Okay, so it seems like these insects are lightly positively charged. Are they just pulling up pollen? Or are there other kind of electrostatic things out in the world that insects might be interacting with, I guess? Are there other things that these insects could be doing with this electrostatic energy? Yes. There are so many cool ways that electrostatic energy is like shaping the insect world. Like when I was reading about this, it was really, there were some mind-blowing examples.

So like bees, for example, can sense if a flower has been visited by another bee before. What? Because like the charge has changed? Yes, because the charge is different. And so they might avoid a flower because it has a charge. that indicates that it was just visited. Okay. And then the other thing, and this came from Sam's research,

his research suggests that some caterpillars that get preyed on or eaten by wasps are, like, able to detect if a wasp is approaching by sensing their positive or negative charge. And when the wasp approaches, the caterpillar, like, will curl up in anticipation of an attack. And so it, like, does this defensive posturing because it senses. the electrostatic energy of the approaching wasp. Did he just, like, put wasps on a string and, like, dangled them over the caterpillars? He actually recreated, like, the electrostatic charge of a wasp, of a predatory wasp,

and looked at what happened to the caterpillar, and the caterpillar, like, responded as if there was a real wasp there. So he knew it was just, like, it literally, it couldn't have been the smell of the wasp or, like, infrasonic wasp. sounds or something, it literally must have been the charge. Yeah, and I think like it's probably worth saying here that like this is a lot of this work is really new and so there aren't like tons of studies showing this over and over again. And so like everything should be taken with like a little bit of a grain of salt. But yeah, that is what his paper showed. I sort of thought you were you were overselling it.

Maybe when you were saying that there's like, you know, a whole invisible force or whatever happening on here. but it does, it really does sound like potentially there's this electrostatic world that insects are interacting with on a fairly regular basis that we're not really aware of. Yeah, and like that is what I love so much about this kind of research. And like I have chills right now just thinking about it because it's like, yeah, it's like a different sense. It's like a sense that we don't use, don't need, but that doesn't mean that, like, like, it's not really important to other creatures.

And I find it, like, pretty humbling to just think that, like, we are only able to observe a sliver of, like, the reality that we live in, and there's all this other stuff going on. So how do we, I guess, how do researchers like Sam figure out what's going on? Like, what do they need to figure out next to sort of explore this literal hidden world? Yeah. So, like, part of it is design. designing super weird experiments, like trying to meet insects where they're at and, like, develop

ways to study how they experience the world. So, like, that's where tying leashes to butterflies comes in. I would say, like, the, one of the frontiers of this research is trying to understand how we humans and our infrastructure, our buildings, our power lines, are affecting all these interactions. Yeah, as exciting and fun as these discoveries are, it may also be a little bit alarming because we're realizing that there are these hidden forces, this secret influence of static electricity, that's actually maybe playing perhaps a significant role in quite a few different ecological interactions. The problem is we as humans, introduce so much static electricity into the environment. So whether this is from things like power lines or our electrical appliances,

but also, you know, a lot of artificial materials, like a lot of our synthetic fibers that our clothes are made of, charge up a lot more than natural materials do. Or if we think about even, for example, microplastics and nanoplastics, like these, materials charge up a lot. And this means that we may have been unknowingly introducing another kind of environmental pollutant into the natural ecology of these animals. So I think like all of the senses that animals use to like live their lives, whether it's like sight or even like sensing the

Earth's magnetic field or electrostatic energy, like all of those senses are disrupted in some ways by our infrastructure, by human things. When I was talking to Sam, he was saying that, like, even just trying to do these experiments in the confines of his lab were difficult because there were so much interference from, like, the building itself, like, the plugs in the wall, whatever. And when you're trying to measure really small changes in charge, it's like, you have to, like, get rid of that noise. And that's what Sam is super interested in understanding next. It's something that I'm very passionate about now trying to pursue is, this is super cool, this is super exciting, but we really need to quickly gain an understanding of how we as humans might be interfering with this electrostatic ecology.

Man, I have to admit, Benji, I really, when you led with like, I'm, I spoke to a researcher who tied butterflies to leashes. I really did not think that you were going to sell me on it to this degree, like to the point where I'm like, give Sam more funding for research, tie more butterflies to leashes. I want more answers here. Dude, well, first of all, like, what did you expect? I'm not going to bring you trash. But, yeah, I don't know.

I guess, like, it's another reminder that, like, it often takes a lot of creativity and these bespoke experiments to answer important questions. Like, the methods might be dumb sounding. The methods might be goofy. They might sound kind of dumb. But, like, ultimately, they're chipping away at something very important to all of us. Benji Jones, folks, our biodiversity reporter, he's literally constantly writing pieces like this on our website.

So you should read his work. This episode was produced by me, Bird Pinkerton, It was edited by Jorge Just. Meredith Hodnott runs our show. Noam Hassamfeld made the music for this episode. Christian Ayala did the mixing and the sound design. Melissa Hirsch, checked the facts. Julia Longoria is the fact that frogs have been making sounds for 180 million years.

And I'm always grateful to Brian Resnick for co-creating the show. Meanwhile, Benji and I are always, always, always on the lookout for weird science that actually serves really interesting, purposes like this Leash Butterfly experiment. So if you know of weird science like this, or if you're doing weird science like this, even better, write in at unexplainable at vox.com. You could also leave us a nice review or rating if you're so inclined or join our membership program. That helps immensely. Box.com slash members. That is Vox.com slash members. But either way, thanks for listening. and unexplainable is part of the Vox Media Podcast Network. And we will be back on Wednesday.