MADDIE SOFIA, HOST:
You're listening to SHORT WAVE...
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SOFIA: ...From NPR.
Hey, y'all. Maddie Sofia here. So ever so often, I pop into an interview a little bit early, and I get to hear the guest talking to our producers, and they don't always recognize I'm there.
SAMMY RAMSEY: Today, we see the lonely life cycle of the periodical cicada.
SOFIA: (Laughter).
RAMSEY: Oh, she's here.
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SOFIA: Dr. Buggs, is that you?
RAMSEY: That is definitely me. You surprised me there for a second. I was just goofing around in my free time.
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SOFIA: You may recognize that voice. He's a SHORT WAVE fan favorite, entomologist Dr. Sammy Ramsey, aka Dr. Buggs. He works at the U.S. Department of Agriculture, and he's here today to talk with us about Brood X, a big group of cicadas that will emerge from the ground this spring.
RAMSEY: This is going to be the 17-year cicada. So 17 years ago, in 2004, they all emerged en masse. And this year, they will do the same thing again.
SOFIA: Brood X is one of the largest groups of 17-year cicadas. There are several species of cicadas in Brood X, but they all look pretty similar.
RAMSEY: So they've got these bright red eyes on top of this black body with bright orange wings, so you're immediately struck by how conspicuous this organism is. It's also larger than most insects. It's sometimes about 2 inches long.
SOFIA: Broods are determined by geography. And if you live where Brood X lives - parts of the mid-Atlantic, Midwest or southern U.S. - you'll probably get to see and hear these bugs. They emerge when the ground temperature hits 64 degrees, and in some places, that will be as soon as late April, early May. And they live for four to six weeks.
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RAMSEY: These cicadas have been underground for 17 years, building up all of this pent-up angst, never seeing the sun. And now it's time for them to emerge. So in some areas, there are as many as 1.5 million cicadas per acre.
SOFIA: Think about that - 1.5 million cicadas per acre. Places like D.C., Maryland and Virginia at the center of it all will be surrounded by these critters whose sole goal is to mate.
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SOFIA: So today on the show, what's up with Brood X? Where have they been for the last 17 years? And, of course, why are they so dang loud? I'm Maddie Sofia, and this is SHORT WAVE, the daily science podcast from NPR.
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SOFIA: We are here with Sammy Ramsey, talking about cicada Brood X, which emerges in force from the ground every 17 years with some caveats. So, Sammy, my first question is what are they doing in the ground for all those years before they come out?
RAMSEY: Yeah, so if I may speak in the vernacular, they're chilling...
SOFIA: (Laughter).
RAMSEY: ...During that period of time. They have pretty much the laziest life cycle that you can really have at that point. So the same tree that their mother is going to lay eggs in - they're going to emerge from those eggs about 10 weeks later and fall to the ground, and they'll be about the size of an ant - so tiny, tiny, tiny little guys. They'll dig underground to about maybe 18 inches below the surface of the soil, and they'll attach themselves to the roots of that same plant that their mother laid eggs in or a nearby plant to that. And as they're feeding on the roots, they're feeding on one of the least nutritively (ph) dense sections of a plant that you can feed on. It's the xylem. This is the piping that's going to move water and some really, really, really dissolved nutrients into the rest of the plant. So there's not a lot of nutrition here. When they're feeding on this, that doesn't give them a lot of energy to do much of anything.
SOFIA: Oh, I see.
RAMSEY: So oftentimes, they stay attached to that same tree root and don't move the entire 17 years.
SOFIA: Wild. So how do they know to all come out at the same time? And why every 17 years, Sammy? Like, why magic 17?
RAMSEY: So you've asked me one of the great mysteries of science and one of the reasons why they even have the scientific name Magicicada. There's something that almost seems magical about it. It seems like the cicadas are actually able to figure this process out by counting. They count through the different years and are able to emerge at 17. But we don't fully understand all the elements of how they're able to coordinate it.
SOFIA: Wild.
RAMSEY: It's an incredible system.
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SOFIA: So these cicadas have been, you know, like, feeding off of this fluid in this xylem. It's not super - you know, I'll go on a venture and say it's not super delicious. It's not very nutritious.
RAMSEY: (Laughter).
SOFIA: I'm making a judgment here. We don't know. But then they - then, you know, a lot, a lot, a lot of them come out all at once. I mean, what is this advantage to coming out all at once? Like, what's the plan here, Sammy?
RAMSEY: So that, to my mind, is the most interesting part of this system. So all of these cicadas emerge at the same time, and the benefit of it is something called predator satiation. And predator satiation is just a fancy way of saying, you can't eat all of us. If all of us show up at the same time, they'll eat as many of us as they can, but they can't eat everything. And then the rest of us will be able to mate. And it seems like a pretty sad way to go about life, but it actually makes some level of sense. The cicadas have decided, I'm not going to put any energy at all into the process of defense. They have no ability to bite, no ability to sting, but they can be the derpy (ph) insects that they are as long as so many of them come out that no single predator or no group of predators could possibly eat all of them.
SOFIA: Got it.
RAMSEY: And what has to be understood here is that evolution doesn't act on the individual. It acts on the population.
SOFIA: Exactly. Yeah.
RAMSEY: And so for the population, this makes perfect sense. But for the individual, that's kind of a bummer.
SOFIA: (Laughter) That's so true, so true. OK, OK. So they come out, they mate, they lay eggs, they die. But, Dr. Buggs, we can't talk about cicadas without talking about that sound they make.
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SOFIA: You know what I'm talking about? Like, it's very distinct. It's kind of like a shake, kind of like a rattle, but really loud. What's that all about?
RAMSEY: So this noise that they make is insanely loud. The species that we have here - this one is going to produce a sound that's between 80 and 85 decibels. That's sort of like the sound of a really loud lawn mower or a truck that's going through traffic. This noise is incredible. They have these sections of their body called the tymbal. There's one on the left side and one on the right side, and only the males actually have them. And they're attached to a set of muscles that pulls them, and as it pulls them, it deforms them in a way that when they snap back, they make a noise. And so the sound waves are just kind of crashing into each other as they're making this noise. And in addition to that, the shape of their abdomen is hollow in a way that allows the noise to be amplified to a substantial extent, and then their wings are actually able to direct the noise as well, so their whole body is not just designed to make this noise but to amplify it.
SOFIA: Could you imagine if your body was a drum, and you had a speaker, and you could shoot that sound? I mean, we can do some cool stuff soundwise. I'm just saying, this is pretty exciting.
RAMSEY: It is very, very exciting. And it's exciting for the cicadas, but it's also probably a really stressful time because all of these males are getting together, trying to sing really loudly, but they're also trying to listen at the same time. They have ears, and they're listening for a female to respond. If she's interested in mating, she'll respond by flicking her wings. And this flicking is a really rhythmic sound that sounds like snapping. And so when the males hear this, they'll dart toward it. The problem is they can easily be distracted, so you'll get a lot of cicadas going after your lawn mower, a lot of cicadas going after your power tools.
SOFIA: Wild. OK, OK. So, Sammy, there's one particular thing that can prevent these cicadas from mating, you know, as effectively that I want to talk about. It's a fungus. It messes - it essentially causes their butts to fall off, for the lack of a better scientific term. Will you talk to me about this fungus 'cause it's a thing out there, Sammy?
RAMSEY: Oh, it's a thing. It is very much a thing. This fungus is called Massospora, and it's a really fascinating fungus in that it is able to penetrate the cuticle of the cicadas. And when it gets inside of their body, it just starts growing, and it eats away at a bunch of important things like the actual gonads. The ability of this cicada to mate is destroyed by this fungus. And then eventually, as it reaches its peak, the butt of the cicada falls off, and you just see this whole mass of spores that's been present inside of this organism's body. And as the cicada is flying around - because keep in mind, this doesn't kill it.
SOFIA: Right.
RAMSEY: So as these cicadas are flying around, the section where their abdomen was has been replaced with a bunch of fungal spores that just fall off. It's been referred to as a flying saltshaker of death because in the same way that if you turn the saltshaker and salt just sort of falls out of the sides of it, the cicada is constantly sprinkling spores onto all the different surfaces that are infective to other cicadas that are nearby. But in addition, the primary way that it infects other cicadas is that somehow it changes the behavior of the male cicadas that are infected with this, where they will actually start flicking their wings and signaling in the same way that females do that they are actually ready to mate.
SOFIA: Tricky fungus.
RAMSEY: Yeah, right? The fungus doesn't seem to care very much that these cicadas have really spent 17 years underground, just thinking about how amazing it's going to be to finally get out of there, and then, boom, your butt falls off.
SOFIA: It's tough. It's tough.
RAMSEY: It's tough.
SOFIA: So, Sammy, you know, why is it important to study cicadas? Like, obviously, this is very cool. It's going to impact quite a few of our human lives, you know, but what are we hoping to learn by following these broods?
RAMSEY: There are so many reasons to want to study cicadas. But when you get a mystery like this one that has persisted for millennia - like, I mean, people have been talking about cicadas in some of the oldest elements of antiquity that we knew of. And it's because these creatures are really, really fascinating in that they're able to sync up their life cycle in this way. They're able to just kind of coordinate something that seems like it would require so much more interaction in order to coordinate.
And so we want to know, how are these organisms doing this? They don't have cellphones. They don't have the ability to call the cicada that's on the other tree and let them know, hey, hey, hey, hey, I know we said that we were all going to emerge on May the 3rd, but it turns out it's forecasted that it's going to rain that day, so we're actually planning on coming out on May the 5th - partly cloudy, but a good deal of sun, 78 degrees. It's going to be wonderful. They can't do that. They can't do it. So how are they coordinating all of this?
And if we could figure things like that out, imagine the different avenues that that could open to us, things that we can't even imagine that we might be able to better coordinate under different circumstances ourselves.
SOFIA: Yeah.
RAMSEY: And so actually looking at the ways that this can develop evolutionarily is really important. And then looking at how the rest of the organisms around them interact with these cicadas - something that they could not possibly have anticipated, these organisms seeing for the first time this huge emergence of creatures - how the energy is used, how the predators deal with this huge influx. All of it is really, really, really helpful for us to better understand as researchers.
SOFIA: Absolutely. Absolutely. I love that. I love that. I cannot wait to go out into this, like, when the brood emerges. I'm so excited. I'm going to be out there. I'm going to be trying not to mess with them too much. You know what I mean?
RAMSEY: Oh, yeah.
SOFIA: But I'm not going to try - I'm not trying to trick anybody into thinking I'm a female cicada, but I want to be standing out there for sure. You know what I'm saying?
RAMSEY: Absolutely. We're going to be walking in a cicada wonderland, and I'm looking forward to it.
SOFIA: All right, Sammy Ramsey, Dr. Buggs, as always, it was a delight. We appreciate you.
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SOFIA: Special thanks to Dan Mozgai of cicadamania.com for some of them sweet, sweet cicada sounds. This episode was produced by Thomas Lu, edited by Geoff Brumfiel and fact-checked by Rasha Aridi. The audio engineer for this episode was Leo Del Aguila. I'm Maddie Sofia, and this is Bug Wave from NPR.
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