[music]

Tanzina Vega: Back with you on The Takeaway, I'm Tanzina Vega. We're going to end today's show with something that should sound familiar to most of your ears.

[thrum sound]

Tanzina Vega: No, that's not a household generator or a low flying airplane. Instead, it's the rhythmic thrum of cicadas, a staple of our summer soundscapes here in the United States. This year, things might be a bit louder as billions of cicadas emerge from the earth after living underground for the past 17 years as part of the so-called great Great Eastern Brood, or Brood X.

To put that in perspective, the last time we heard or saw Brood X was the same year that Facebook was launching as a social network and the first legal same-sex marriage was taking place in Massachusetts, and it was also a time when Donald Trump was known as the host of The Apprentice rather than our former president.

[thrum sound]

Tanzina Vega: For more on the upcoming once in 17 years cicada spectacle, we're joined now by Dr. Matt Kasson, an Associate Professor of forest pathology and mycology at West Virginia University. Matt, welcome to the show.

Matt Kasson: Thanks, Tanzina. Happy to be here.

Tanzina Vega: There are thousands of cicadas species worldwide, why are we making such a big deal about the Brood X?

Matt Kasson: Well, there are cicadas worldwide, about 3,000 species, but in North America, we have a very unique phenomenon and that is the 13 and 17-year periodical cicadas. Nowhere else on Earth did we see such long live cicadas that spend most of their life underground to emerge in this truly spectacular spectacle and their numbers far surpass anything we've ever seen.

Tanzina Vega: Just to be clear, these are harmless, right?

Matt Kasson: That's right. Oftentimes people are afraid when they see large insects in large abundance, but they pose no threats to us as humans. They have kind of sucking mouthparts for feeding on the sap of trees. Even if they land on us, they can't hurt us and they do have kind of sword-like structures on the back of females. Those are for laying eggs and body tissue. They can't sting us they can't bite us.

Tanzina Vega: The cicadas of the Brood X which are periodical cicadas, how do they compare to the cicadas we see in here annually?

Matt Kasson: Well, for one, they have a much longer life cycle. They're called 17 years cicadas because they spend so much time underground developing. Most of their life is spent in a juvenile stage, we call it nymph, feeding on the roots of plants underneath our feet. They're there all along, we just don't notice them, but when they come up, they come up in kind of a synchronized fashion.

Within a two-week period we'll see billions of cicadas emerge in the areas where they're known to occur. This Brood X covers about 15 States, and we'll see a major epicenter in and around the greater DC area. This compares to annual cicadas that come out every year, but really don't have the numbers. You hear them, but you don't really see them. The periodical cicadas, you can't miss seeing them just because they'll be up along with their billion other friends.

Tanzina Vega: I want to pose an existential question here, Matt, do these periodical cicadas or Brood X's, who have been developing underground for 17 years, do they have a purpose? I guess that is existential in a lot of ways, but why? What is the point of them emerging right now or is it just strictly because of their cyclical development cycle?

Matt Kasson: There's a lot of people that actually study the math behind Cicada emergence, and obviously, there's a lot of theory that goes into it, but really it's about predator evasion. If they wait long enough, then the collective memory of the predators that feed on them can't predict when they're going to come up.

When they do come up, they do provide a huge resource for every snake, bird, and fish in the area. They just basically fill all of them. You see a real boom in those populations in years that cicadas emerge. The other benefit is, of course, the fertilizer that they add to the soil as they die and integrate back into the soil.

Tanzina Vega: We played some sound at the very top of the segment here, because that's a sound that a lot of people recognize. How do cicadas make their loud sounds, and how loud can they actually get? Are we thinking, we're going to be trying to do the show and all windows have to be closed so we can avoid cicada background noise here?

Matt Kasson: Yes. Great question. Well, when you're hearing cicadas, you're really only hearing the males. The males are the ones that have a call and that call is meant to impress a female into being receptive to mating. The periodical cicadas are actually three distinct species. You have three separate calls by males to impress their respective females. You're hearing the overlap of three different cicada species in time and space.

To answer your other question, how loud is it? If you've ever sat next to high tension power lines or a generator going non-stop, it can be deafening outside, especially in more heavily wooded areas. Wooded suburban environments or wooded parks around urban environments, definitely.

Tanzina Vega: It's a mating call essentially. If all of these male cicadas are out here making all this noise, do they drown each other out?

Matt Kasson: Absolutely. In fact, they have to get close enough to the female to have her hear their call, but they're also waiting for a female to flick her wings to indicate that she's receptive to mating. They get as close as they can. They scream as loud as they can, and they wait for her to flick her wings and say, "Okay, I'm open to the idea of mating".

Tanzina Vega: Matt, I had to laugh because it sounds like the lady cicadas are in charge here.

Matt Kasson: Absolutely. There's no doubt about that.

Tanzina Vega: You have to be excited about the fact that the Brood X are emerging. For scientists, for folks in your community, you're a forest pathology and mycology professor here. What does this mean for you? This has got to be a pretty big deal waiting 17 years for this emergence.

Matt Kasson: Well, yes, absolutely. This is the biggest, so there's a lot of excitement around that. There are other Broods that emerge in other years and we as people that study cicadas and we study fungi that infects cicadas, we're always traveling around to find these Broods in various locations. With Brood X, you don't have to travel too far because it's emerging in 15 States. Whereas other broods might be restricted to just a few counties in one state. It's a real great opportunity to look at different aspects of the cicada life cycle and understand more about its genetics and its contemporary pressures and things like that.

Tanzina Vega: Less than a minute to go, any apps for the cicada curious, people who want to follow where these folks are- where these cicadas are going?

Matt Kasson: Yes. Definitely, I'd encourage people to check out iNaturalist and Safari Cicada, which are two great apps for tracking cicadas, but just encourage you to get out there and see them because it really is a true spectacle.

Tanzina Vega: Sounds like an amazing thing. Matt Kasson is an associate professor of forest pathology and mycology at West Virginia University. Matt, thanks so much for sharing all wisdom cicada-related with us. We really appreciate that.

Matt Kasson: Thanks for having me.

[00:08:00] [END OF AUDIO]

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