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2 cicada broods will emerge around the same time in the U.S.

SCOTT DETROW, HOST:

A once-in-a-lifetime event will take place in a few weeks, and it involves cicadas.

(SOUNDBITE OF CICADAS BUZZING)

DETROW: For the first time in 221 years, two different broods of cicadas will emerge around the same time across regions of the U.S. To make sense of this event and to know what exactly we are in for, it was only natural to call up the bug guy. Michael Raupp is a professor emeritus of entomology at the University of Maryland and the author of the Bug of the Week newsletter. Thanks for being here.

MICHAEL RAUPP: Hey, Scott. My pleasure. Always fun to tell bug stories about some of my favorite insects on planet Earth, the periodical cicadas.

DETROW: I need to start with the big question. I read that introduction, and my thought is, wait a second, didn't we just do this? 2021 was an enormous cicada year. What is different about this year? What is different about what's coming up?

RAUPP: Yeah. Well, we were only sort of kidding to say they are only out every 17 years. Actually, in some part of the country, almost every year we have periodical cicadas. What is so special about this particular event is in parts of the Midwestern states, we're going to have a simultaneous emergence of what we call the Great Southern Brood - that's Brood XIX - and this is going to bump right up against Brood VIII, which is the Northern Illinois Brood. This hasn't happened in that part of the country since Jefferson was signing the Louisiana Purchase back in 1803. So this is what makes it so special, that confluence of two broods of cicadas. It's going to be seven species of cicada in total that are going to be emerging out there in the Midwest and throughout parts of the South this year.

DETROW: So what are the hot spots here or the loud spots here?

RAUPP: Whoa, baby. Well, we know for a fact that that Northern Illinois Brood in parts of Illinois, Wisconsin, Michigan is a very dense brood. So the big boy band is going to be cranking it up in the treetops, probably to 100 decibels, hoping for romance. In parts of the South, Virginia, the Carolinas, swinging across to Alabama, Louisiana, Oklahoma, that Brood XIX is also going to be comprised in some locations that haven't been disturbed for the past 13 or 20 years, or maybe 100 years. High density - so great volumes, great densities - it's going to be spectacular.

DETROW: In the regional overlap areas, is there going to be some brood-on-brood interaction?

RAUPP: Well, that's the million-dollar question, isn't it? Yeah, there's a possibility because they will co-occur in very close proximity in parts of Illinois. The problem here is that the four species of 13-year cicadas, the Brood XIXs, are going to be identical in appearance to the Brood XIII cicadas. So just visually recognizing these cicadas will be virtually impossible. We also don't have sound molecular techniques yet to be able to resolve this.

The real concern here is the hybrid situation does create a possibility that we could have an off-year occurrence of cicadas, and the problem here is, is when we have hybrids, it kind of defeats this very bizarre strategy of periodical cicadas, which we call predator satiation. This is one of the strangest phenomenon on planet Earth when it comes to survival. Their whole game is to simply emerge in such vast numbers simultaneously that they will fill the bellies of every predator that wants to eat them, and there will still be enough left over to perpetuate the species. So any hybridization that would tend to flatten that curve to disrupt that synchrony basically works against that predator satiation.

DETROW: In the places where this is going to be happening, is it going to be similar to three years ago, just in terms of the decibel level and just the multitude of cicadas? Like, I have memories of just seeing tree stumps moving and swarming, and it was...

RAUPP: Yeah.

DETROW: ...All cicadas.

RAUPP: Yeah, there's no question the densities are going to be exactly like they were here back in the big brood in 2021. There will be some areas where cicadas are thick. There will be other areas that are not going to be as dense, but there's no reason that I'm aware of to expect that it's not going to be just as raucous and just as dramatic as it was here three years ago.

The problem, of course, Scott, comes if there's been significant development in terms of the removal of the trees that periodical cicadas depend on or agriculture or the worst-case scenario where we've created impervious surfaces for roadways, buildings, shopping malls and such because these guys simply can't emerge out from under cement. And if there has been development in these areas in the intervening years, that's what poses the big threat to the periodical cicadas that we see.

DETROW: Got it. What are you most looking forward to about this?

RAUPP: Well, for me, we're going to have a Brood XIX emergence in extreme southern Maryland. I had a chance to go back and commune with these guys and gals back in 2011. It was remarkable. The densities were high. They're hanging on down there. Just fingers crossed that they've been able to survive another 13 years and I can go out and witness them. I'm also very interested in documenting some of their evasive behaviors. Periodical cicadas are sometimes called defenseless species, but really, they've got some very clever behaviors that allow them to escape their predators. And I want to learn a little bit more about those defensive behaviors. So I hope to go down to St. Mary's, hang out with the broods and see what they're up to.

DETROW: Michael Raupp is professor emeritus of entomology at the University of Maryland. Michael, thanks so much. Enjoy the cicadas.

RAUPP: Thank you, Scott, and I hope you get a chance to see these rascals, too. That's going to be just phantasmagorical. It's going to be Mother Nature's second epic event. We had this celestial epic event this year, and guess what? Now we're going to have an epic entomological event. So...

DETROW: They were a few weeks too late.

RAUPP: Yeah, really...

DETROW: It would have been great.

RAUPP: Well, we tried to juice them (ph) out early with global warming, but they weren't buying...

DETROW: (Laughter).

RAUPP: ...So they decided to stay underground on the right schedule, which is good for them, I think.

DETROW: All right. Michael Raupp, thanks so much.

RAUPP: Thanks so much, Scott.

(SOUNDBITE OF MUSIC) Transcript provided by NPR, Copyright NPR.

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