Episode 4: How cicadas become flying saltshakers of death

When Brood X cicadas emerge this year in the eastern U.S., National Geographic Explorer Matt Kasson will be on the lookout for a fungus that destroys these noisy insects—but not before it sends them on a wild trip.

A Brood X, 17-year cicada emerges from its nymphal exoskeleton. Kensington, MD.
Photograph by Darlyne A. Murawski

After 17 years underground, so-called Brood X cicadas get a fleeting moment in the sun and commence their deafening buzz. But periodical cicadas can’t escape a silent killer: a fungus that eats them from the inside and forces them into a rabid mania. Follow National Geographic Explorer Matt Kasson as he tracks these “flying saltshakers of death,” and hear why scientists say cicadas should be respected, not feared—even if they do raise a ruckus in your backyard.


(Cicada sounds)

PETER GWIN (HOST): What you’re hearing right now is a love song. OK, you’re right. They’re cicadas. Actually male cicadas, to be exact. But stay with me, because this isn’t an episode about just a really loud swarm of bugs. It’s actually a crazy tale about an ancient underworld: sex, drugs, and flying zombies. And it starts with this sound. 

This massive chorus of male cicadas—think millions of crooning Frank Sinatras—and they’re all desperately competing with each other to attract a mate in their very few last weeks of life. 

And their species depends on them finding a love connection.

CHRIS SIMON (BIOLOGIST): They’re calling in the females. And when the females get close, they even change their song. 

GWIN: This is Chris Simon. She’s a professor at the University of Connecticut and one of the world’s top cicada experts. And she’s studied these cicada songs closely.

SIMON: And so It’s like three parts. So when the female clicks to the male, then he’ll change his song and he’ll just start going like:

(Sound of cicada mating call) 

SIMON: And then the female will come closer, and then they sort of touch their front feet facing each other. 

GWIN: Ah, it sounds kinda sweet when you put it like that. So the Frank Sinatra cicada woos the female cicada and they mate and have babies, and, you know, cue the happy ending music. 

(Tape reversing sound effect)

GWIN: Not so fast, because there’s a parasitic fungus lurking. And the fungus is waiting for these Frank Sinatra cicadas to show up so they can pump them with drugs, hijack their brains, and turn them into what one scientist calls “flying saltshakers of death.” See, I told you it was a crazy tale.

I’m Peter Gwin and this is Overheard at National Geographic: a show where we eavesdrop on the wild conversations we have here at Nat Geo and follow them to the edges of our big, weird, beautiful world. And baby, this week it’s weird.

This week: After 17 years underground, an infamous brood of cicadas are blasting their mating calls across a big chunk of the United States. We’ll make the case that these fascinating creatures deserve respect, even if you need earplugs to block them out. And we’ll go deeper into the world of flying saltshakers of death, including the unexpected discovery that led a cicada researcher to get in touch with federal drug enforcement agents. 

More after the break.

GWIN: OK, I have to start this story with a confession. I used to be a cicada hater, straight up. It started about 10 years ago when I got an incredible opportunity to travel to China and interview legendary kung fu masters at the Shaolin Temple. 

It was cicada season in China. And I wasn’t really paying attention to that. I mean, you know, this was a dream come true. So I recorded the interviews so I wouldn’t miss anything, and the stories were just spectacular. But later, when I listened to the tape, the kung fu masters’ voices were almost completely drowned out by cicadas buzzing outside. 

SIMON: Cicadas have interrupted many different things. I have a whole collection. You know, like golf tournaments, murder investigations, weddings.

GWIN: Chris Simon says haters like me, we could look on the bright side. 

SIMON: If they come out in the middle of your wedding, you'll have a much more memorable wedding than anybody else who doesn't have cicadas at their wedding. And people will be talking about it for many generations.

GWIN: Um, I ran this theory by my wife. Yeah, no, she’s not buying it. But we’ll cut Chris some slack. She’s been studying cicadas for almost 50 years. 

SIMON: It was in 1974 when I first went out to study them. And so I set out from Long IslandI was at Stony Brookand drove down the East Coast, and we just would pull into a town and then we would ask where the cicadas were. And you could go into any hardware store or soda fountain and people would tell you exactly where they were.

GWIN: But even though Chris has studied cicadas more than just about anybody, there are still some questions about these bugs she just can’t answer. Cicadas come out every year. When I hear cicada songs, I know it’s summer or I’m watching a Ken Burns documentary.  

Cicadas have been around for hundreds of millions of years. They even lived alongside the dinosaurs. Today there are thousands of different species, spread all over the world. But in North America, we have these special cicadas. They’re called periodical cicadas. And they live almost their entire lives hidden deep underground. They nestle among tree roots and silently sip fluids from the trees, biding their time. And then, after either 13 or 17 years, depending on the species, an entire group will emerge all at once. 

DOUGLAS MAIN (REPORTER): So I guess the obvious place to start is the emergence, which is the end and the beginning in a way.

GWIN: Douglas Main covers the insect beat for National Geographic. He says when the soil temperature hits 64 degrees, that’s the cue for the cicadas to emerge. And they have one thing on their mind. OK, kids, cover your ears: S-E-X.

MAIN: And it's really at this point all about reproduction. So the males and females climb up into the trees and the males start calling. 

GWIN: OK, think spring break in Daytona Beach but for insects. Each cicada has only a few weeks to soak up the sun and attract a mate before it’s all over. 

MAIN: They flex this organ called a tymbal. And it's basically males flexing their muscles and making noise and trying to attract females. 

GWIN: In fact, cicadas are so desperate that you can easily attract them by mimicking their call with a finger snap. There are different groups of cicadas, called broods, that pop up in different years. But this year’s brood is special. You might have read about Brood X.

SIMON: Yeah, so it's actually Roman numeral ten, not “X.” It’s brood ten. And what makes it so special is it's the largest 17-year brood of periodical cicadas.

GWIN: And when she says large, it’s truly mind-boggling. By some estimates, the number of cicadas emerging in Brood X is in the trillions. That’s right, trillions with a T. Every single one of them has been living underground since their parents last appeared in 2004so like, three presidents, two popes, and twelve versions of the iPhone ago. 

SIMON: Periodical cicadas are basically trapped being periodical. They can't get out of it because all of their biology now is geared towards this life cycle.

GWIN: Chris says cicadas can sense changes in the trees. That’s how they know what time of year it is. But how they count to 17 years is still a mystery. Emerging in one ginormous wave is the only trick cicadas have up their sleeve. Individually, they’re helpless. But in the trillions, they’re overwhelming. 

And if the story just ended there, it’d be pretty amazing. But buckle up. It takes a bizarre twist. You haven’t heard about the zombies yet.

MATT KASSON (SCIENTIST): If you had asked me, you know, six years ago, Are you going to become a cicada researcher? I would have said, Are you kidding me? Like, I know nothing about cicadas.

This is Matt Kasson. He’s a professor at West Virginia University, and also a National Geographic Explorer. In 2016 there was a cicada emergence in West Virginia. And it sent Matt down the rabbit holeer, cicada hole. The thing about Matt is he’s not a bug specialist. He studies fungi. 

KASSON: And two of my students who are really enthusiastic about cicadas said, Hey, did you know that there's a parasitic fungus that is specific to periodical cicadas? And I said, well, OK, tell me more. Tell me more. 

GWIN: Yeah, a parasitic fungus that preys on cicadas. Something only a scientist could love. And this is where things start to get really trippy. Matt and his students collected these fungus-ridden bugs. When I talked to Matt on Zoom, he actually had an infected cicada sitting right next to him. And he held it up to his camera.  

KASSON: And if you look, you could see that the backside is replaced by a fungal plug there. 

GWIN: It’s all chalky white, I guess. 

KASSON: It's chalky white. It's either like a middle school eraser or like a math teacher’s chalk, you know, so it's definitely noticeable that something's wrong with the backside of the cicada.

GWIN: The fungus eats the cicada from the bottom up. Yeah, it’s gross, I know. But eventually the lower half of an infected cicada is completely gone. 

KASSON: Think about your own body. If you had your legs chopped off, you'd probably be lethargic and probably feel pretty crappy. 

GWIN: But not these cicadas. Again, it only gets weirder. The fungus is extra devious. Not only does it make the cicadas waste away. It also turns them into over-caffeinated flying machines. Or as Matt calls them, zombie cicadas. 

KASSON: Because they're still very active when they have this fungus erupting out of the back side of them, they'll fly around and spores will flake off, similar to a tipped saltshaker. So they're basically flying saltshakers of death. 

GWIN: Flying saltshakers of death, raining zombie destruction upon the insect world. Come on, tell me you wouldn’t watch that movie. It turns out this fungus is called Massospora. And the more questions Matt asked about it, the weirder this fungus became. For starters, how could Massospora make a half-eaten cicada go on a bender like nothing’s wrong?

KASSON: We were trying to figure out if there were some kind of chemical compounds produced by the fungus that could be inciting this behavior. Well, it turns out that Massospora cicadina, the one that we find in periodical cicadas, is loaded full of cathinone.

GWIN: Don’t worry, you don’t have to be a chemist to follow this. Cathinone is a type of amphetamine, the family of stimulants also known as speed. And when Matt analyzed the infected cicadas… 

KASSON: We found the same compound, the same exact compound in Massospora-infected cicadas. And they were loaded with it, which tells us that amphetamines are probably contributing to this prolonged wakefulness. 

GWIN: Oh my gosh. Wow. So basically, these are like, they're on speed trips, is what you're saying.  

KASSON: That's exactly right.

GWIN: OK, so, drugged-up cicadas. That was totally out of left field. But it was also an extremely rare discovery. Cathinone occurs naturally in one type of plant. But nobody had ever recorded a fungus quite like this. 

KASSON: When this first happened, when we first made the discovery, this was, you know, my Ph.D. student, Dr. Greg Boyceyou know, you would have thought that he and I had consumed several cicadas just based on the natural high we had from this discovery. We couldn't contain ourselves. 

GWIN: So Matt kept digging. Maybe these cicadas were hiding more undiscovered weirdness. 

KASSON: Now if that wasn't crazy enough, we got ahold of a second cicada out West, which is an annual cicada.

GWIN: OK, so this would be a cousin to the periodical cicadas, you know, that come out every 17 years. It was infected with a slightly different species of Massospora. Just like the other ones, it had a chalky fungal plug sticking out of its backside. So Matt wondered, did this fungus work the same way?

KASSON: And when we checked those plugs, we didn't find the amphetamine. We found psilocybin, which is the hallucinogenic compound found in magic mushrooms.

GWIN: So basically, these fungi are drug dealers, is what you're saying? 

KASSON: Absolutely.

GWIN: So not only are those flying saltshakers of death spreading a parasite and turning other cicadas into zombies. Some of them are also on a psychedelic trip. Turns out there’s a lot more going on with cicadas than you thought. 

Discovering the psychedelic chemical was just as unexpected as finding speed. And it actually put Matt in an uncomfortable position. All of a sudden, he had two different illegal drugs in his lab.

KASSON: When we originally discovered these compounds, we did send an email to the DEA, wondering if we needed a permit to study them because it was an inadvertent discovery. So, you know, it all worked out fine, but it was a little nerve-racking at the time. 

GWIN: Yeah, imagine being the DEA agent fighting cartels who stops what he’s doing to answer that email. They said, Yeah, OK, thanks for letting us know, but you’re good. For one thing, the amounts of either chemical in cicadas is really tiny. But Matt says there’s more to this discovery than just the shock value. He thinks one group in particular should definitely pay attention to zombie cicadas: pharmaceutical companies.

KASSON: I tell people all the time, I really think that these interactions between insect-destroying fungi and their insect hosts is the next frontier for drug discovery.

GWIN: After all, we have fungi to thank for penicillin. And also statins, which help lower cholesterol. And there are even more unexplored species of Massospora all over the world. So who knows what other weird chemicals are waiting to be found? 

KASSON: It just tells us that there's a lot there hidden below the surface. You know, it is stranger than fiction by like an order of magnitude. 

GWIN: OK, so let’s recap. Trillions of cicadas emerge all at once. Some of them are drugged-out zombies. And they make enough noise to drive everybody crazy. So if you’re wondering, Why is this something to celebrate, Douglas Main says we should take a different perspective.

MAIN: They don't bite. They don't sting. They're not toxic. They're basically harmless to most trees. 

GWIN: And they have a positive effect on the environment. Remember, cicadas’ only strategy is to overwhelm their predators. Otherwise, they’re basically defenseless. 

MAIN: Anything that has a mouth will eat one. Birds and cats and lizards and frogs and, you know, anything that has a taste for cicadas will have a very good year.

GWIN: And cicadas draw attention away from other insects. Butterflies and moths are more likely to survive because predators are just not interested. Another bonus: cicadas are a great natural fertilizer. When the party ends, all of those cicadas die at the same time. So there’s a rich layer of nitrogen going back into the soil. And then there’s one other way to enjoy cicadas.

MAIN: They're edible. They're tasty, according to some people. I actually have not tried them yet.

GWIN: OK, so do you have a cicada recipe? Are you going to do, like, are you going to eat them raw? Are you going to, like, you got stir-fry planned? Or what’s your recipe here? 

MAIN: Stir-fry is—does sound like a good idea. I mean a lot of people have likened them to shrimp. Some people call them tree shrimp, which I think is a pretty funny term. 

GWIN: The trick to gourmet cicadas is to catch them before they harden—like soft-shell crab, according to researcher Chris Simon. Although even then, she’s not a big fan. 

SIMON: I did taste them at a party where these other people had collected some and they made them as sort of a Sichuan sauce. And so they stir-fried them in a wok. They're kind of crunchy, but they mainly just tasted like the Sichuan sauce.

GWIN: Even if you don’t want to try eating them, Chris says people caught in the middle of this brood shouldn’t take it for granted. 

SIMON: I get emails from people in California asking me, Where's the best place to see them? What time should I go? That sort of thing.

GWIN: So what is the best way to take in these trillions of insects? Chris says, go out into your yard, or use the internet to find a good place. And then sit back and let nature do its thing.

SIMON: Find some kids. Go out in the evening and then watch them come out of the ground, and just watch the kids’ faces. And then, you know, experience the sound. 

(Cicada sounds)

GWIN: That sound? It’s an ancient love song. But it’s also a song of survival and a song of freedom after long years underground. And whether you like it or not, it’s a song that will come back in 2038.

More after the break.

If you want to know more about zombie cicadas, well, you’re in the right place. Check out our show notes for pictures and even more information. We also have guides to help you understand Brood X cicadas. You can find out more about cicadas’ biology and how exactly they pull off this lifestyle. Also check out Douglas Main’s article explaining why these gigantic emergences are a good thing. And for the culinary crowd, we have a few cicada recipes to get you started. Find out how to enjoy cicadas in cocktails, in cupcakes, and even candied and baked in the oven. Yum.

That’s all in the show notes. They’re right there in your podcast app. Happy snacking.


Overheard at National Geographic is produced by Jacob Pinter, Brian Gutierrez, Laura Sim, Ilana Strauss, and Menaka Wilhelm. 

Our senior producer is Carla Wills.

Our senior editor is Eli Chen.

Our executive producer of audio is Davar Ardalan. 

Our fact-checkers are Julie Beer and Robin Palmer.

Our copy editor is Amy Kolczak.

Hansdale Hsu composed our theme music and engineers our episodes.

Thanks to Greg Holmes, who provided cicada recordings heard in this episode.

This podcast is a production of National Geographic Partners. 

The National Geographic Society is committed to illuminating and protecting the wonder of our world and funds the work of National Geographic Explorer Matt Kasson.

Whitney Johnson is the director of visuals and immersive experiences.

Susan Goldberg is National Geographic’s editorial director.

And I’m your host, Peter Gwin. Thanks for listening, and see y’all next time.


Want more?
Trillions of cicadas appearing at once is a good thing, we promise. Learn more about how periodical cicadas do it

And see photos of annual cicadas from the National Geographic Photo Ark. Also, bring Brood X to your taste buds with recipes for cocktails, cupcakes, and other buggy treats.

Also explore:

Read on about the weird world of zombie cicadas. And track cicada emergences near you with Cicada Safari or other smartphone apps.

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