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Brian Lehrer: Brian Lehrer on WNYC. After a long period of isolation, a more social summer is just around the corner and that's especially exciting if you're looking to find a romantic partner. But wait, I'm not talking about humans and the ensuing 'hot vax summer' with young adults being vaccinated. I'm talking about cicadas, specifically the Brood X, a big group that will emerge en masse this spring in a matter of days in parts of the Northeast, we're told, as well as the Midwest and Southern US. They've been underground for a total of 17 years.

Just imagine how much bread-baking and Netflix they must have gone through, and here's what they sound like. The volume of these many, many, many, many, many cicadas is one of the things that, depending on where you are in our area, you will be hearing soon, they say. With me now is one of the 'theys', Dr. Gene Kritsky, Dean of the School of Behavioral and Natural Sciences at Mount St. Joseph University in Cincinnati and author of many books on bugs, including Periodical Cicadas: The Brood X Edition. Dr. Kritsky, thanks for coming on. Welcome to WNYC.

Dr. Gene Kritsky: Pleasure, it's great to be here.

Brian Lehrer: First of all, am I saying the name of this insect correctly? It's cicada, not chicada.

Dr. Kritsky: You're correct. It is cicada.

Brian Lehrer: What's a cicada?

Dr. Kritsky: Cicadas are insects that belong to the group that includes things like stink bugs and bedbugs and aphids, and they're more closely related to aphids than they are to bedbugs. They've got piercing, sucking mouth parts and there's a whole family of cicadas of more than 3000 species worldwide. We're talking about particularly our three species that occur once every 17 years, that emerged together in year classes, which we call broods. That's what's happening this year, is the emergence of Brood X.

Brian Lehrer: What did they do for 17 years?

Dr. Kritsky: It's not an exciting life. They've been underground sucking on a tree root and making tunnels and moving from one part of the root to the next. They are xylem-feeders. This takes people back to their biology courses, but that the vascular tissue that takes water and minerals from the soil up to the leaves. They're feeding on that. They're usually between, for the first few years, down about between 6 to 12 inches below the surface. Then, they go between 8 and 4 inches for the middle years, and now they're probably within an inch of the surface now with a hot tunnel that goes down about 6 to 8 inches as well, and they've been quietly waiting for all the right conditions for them to come forward.

Brian Lehrer: How do they know to all come out at the same time?

Dr. Kritsky: The trigger is temperature. Cicadas are really insects and climate. When the soil temperature reaches 64 degrees Fahrenheit, that's the first inclination that something's going to happen for them, and then, usually after just a nice soaking rain. When those two conditions are met, the first cicada year, that's when the emergence starts in earnest, really good numbers happening.

Brian Lehrer: Why 17 years? The conditions you've just described happen every spring. Why isn't it 16 years or 18 years?

Dr. Kritsky: That's one of the discussions we've had for many, many years. It turns out that 17 is a prime number, which is thought to be important [chuckles]. The thought is that being a prime number, there is no way that a predator could or a parasite could evolve synchrony through intermediate stages and so that's protected them now--

Brian Lehrer: Prime number for the non-math nerds in the audience means it's not divisible by anything but itself and one.

Dr. Kritsky: And one, that is correct. There's another group of periodical cicadas in the US called 13-year cicadas, and that's also a prime number, but we do know of two other kinds of periodical cicadas. One has an eight-year cycle and one has a four-year cycle. That prime number idea may not hold as much water as we once thought it did. We believe that the long-life cycle in part is a response to their evolution during the ice ages, and a way to cope with uncertain weather conditions. They could have come out in 13 years, or if that wasn't suitable, they could go out, come out in 17 years. There may be just a single genetic switch that's involved with that.

Brian Lehrer: Wow. Listeners, we have time for a few questions, everything you've always wanted to know about cicadas, but didn't have anyone over to dinner to ask. You can now ask Dr. Gene Kritsky at 646-435-7280, 646-435-7280. Anyone listening, seen or heard one yet this year? 646-435-7280. How long do they live? Are there any who would have been coming out in 2004, 17 years ago, and now again?

Dr. Kritsky: No. Actually, we're looking at their kids. The adults and parents die shortly after the eggs are laid. They have a very short adult lifespan, just about four weeks, and it takes two weeks for the entire emergence to take-- It takes two weeks for all them to get out of the ground and then the last ones [unintelligible 00:05:51] . Our experience with the adults lasts about six weeks, but you asked about where we're seeing them.

I can tell you that the Cicada Safari, the app that I developed for helping to map, the closest we've got, I've got reports of nymphs, not the adults yet, in Princeton and just North of West Windsor township. I have a rather interesting report from, was it South Amboy, is the closest to New York city that I've got, and we have historical records from New York.

There may be some still on Long Island. There are, but there are historical records that go back to 1919 and 1902 of them being in New York, and then one record from 1885 in Central Park, but nothing's been reported since, so they may no longer still be there. It's surprising to think of periodical cicadas are going extinct, but that happens. For example, Brood XI was declared extinct in 1954. The last time we saw Broox XI cicadas was 1937, and that was up in the Boston area.

Brian Lehrer: What is Brood X to refer to these cicadas mean? And where are Broods one through nine?

Dr. Kritsky: There's 15 broods in total, three 13-year broods and 12 17-year broods. Brood X is a designation that was given to it in 1893. There was so much confusion on what different broods were. There was two brood systems of remembering cicadas, and a third system that just used emergence year, and it was rather confusing. A man by the name of Charles Marlatt said, "Okay, let's settle this. Every 17-year cicada that comes out in 1893, that's going to belong to Brood I.

Every 17-year cicada that comes out in 1894, that belongs to Brood II, and numbers 1 through 17 were for 17-year cicadas. Then, for 13-year cicadas, every 13-year cicadas came at 1883, that was Brood XVIII and numbers 18 through 30 were reserved for 13-year cicadas. Brood 10 is the 10th in that numbering sequence, but it's of most significance because it emerges in a number of urban areas, and especially in the late 19th century, it was emerging in Philadelphia, Washington, Baltimore and Cincinnati.

Those were four of the largest cities Western New York in the US, and there were scientists there that watched these things that wrote stuff down. So, a lot of our fundamental information that we had early came from Brood X emergences, and usually major papers are published around Brood X because they occur in such large areas. That's why it is the biggest of the 17-year cicada Broods covering now 15 States and the District of Columbia, but it's historically important as well as biological importance.

Brian Lehrer: Let's take a phone call from Hugh, are you in Sussex County or Suffolk County?

Hugh: Sussex, New Jersey.

Brian Lehrer: Sussex, just to be clear for our listeners, because I wasn't sure. Sussex is the westernmost county in New Jersey. Suffolk is the easternmost county in New York. So, Hugh, hi.

Hugh: Hi. My question is, do cicadas cause leaf damage that will result in less than spectacular for a foliage year.

Dr. Kritsky: They can. The damage that's caused by the cicadas is when the female lays her eggs in the new growth of trees. Occasionally, that process of laying her eggs when she literally drills into the terminal branches of the tree and deposits her eggs, that can sometimes tear up the vascular tissue causing the leaves to turn brown. Sometimes the tree will even break at that point, and it looks like it's been hit by big hailstorm.

I'll be ugly this year if it's heavy infestation, but back in 1869, there was this paper published in the newspaper called American Entomologists that was titled 'Out of evil cometh good'. It turned out orchards in Illinois and Missouri where Brood X had emerged the year before were reporting a bumper crop the following year after a Brood X emergence. That damage that the cicadas cause, which is called flagging, because it looks like the brown leaves are flags, actually leads to a greater flower set next year. The trees may look ugly this year, but there's the potential of-- like a natural pruning, they could have a larger flower set next year. That's something that we've been watching.

Brian Lehrer: Randy in Pound Ridge, you're on WNYC. Hi, Randy.

Randy: Hi. Basically, we've had a bug at our house called the cicada killer for the past several years. They're very large, and they're very dangerous-looking and they're horrible, and that was before this brood is going to be becoming a problem for us. I wonder if your guest can tell me anything about cicada killers and whether I'm going to see an influx of them as well?

Dr. Kritsky: Certainly, the cicada killer wasps do come out every year and they're primarily adapted to feed on the annual cicadas, the ones that come out, the cicadas that start coming out in early to mid-July and last through into the early fall. In most instances, the periodical cicadas will be dead and the carcasses at the base of trees before the cicada killer wasps come out of this. It's not to the cicada killer wasps' advantage to feed on periodical cicadas because they come out earlier in the year and only once every 17 years. They've evolved to provision their nests with paralyzed adult cicadas that come out every year. This will not lead to an increase in those numbers.

Brian Lehrer: Matt in Manhattan, you're on WNYC. Hi, Matt.

Matt: Oh, hi. Yes, I grew up in Oklahoma and it seems to me in the late '60s that I got more than-- I'm not entirely sure, but I didn't live there long enough. I moved here when I was 18, that I got more than one batch and they went like [mimicks cicada sounds] instead of the sound that I heard Brian play earlier. I was just wondering, is there that much of a variance between the different parts of the country?

Brian Lehrer: Here again, here are the cicadas that supposedly were recorded, I think, in this area the last time and they're probably going to sound something like this.

[cicada noises]

Brian Lehrer: Now, Dr. Kritsky, how many cicadas would it take to make that sound?

Dr. Kritsky: That would probably take a couple of thousands maybe in a cluster of trees. Those are periodical cicadas.

Brian Lehrer: Compared to the sound that Matt was just making of the cicadas from Oklahoma.

Dr. Kritsky: The sound that Matt was making sounds like one of the grass cicadas. There are several species of cicadas in Oklahoma. There are-- and I don't know where Matt lived in Oklahoma, but only Brood IV occurs in Oklahoma of periodical cicadas, and that's along the extreme eastern part of the state. Matt, if you are still on the line, did you live along the east side of Oklahoma?

Brian Lehrer: Matt's gone.

Dr. Kritsky: Okay Matt. Well, but it sounds like the sound that he was illustrating sounds like one of annual cicadas, the ones that come out a little bit later in the summer. Brood IV of the periodical cicadas does occur there, but it's very sparse and it's restricted to the eastern part of the state.

Brian Lehrer: Before you go, I've read that you've eaten a fair number of cicadas. Is that true and are they good?

Dr. Kritsky: I wouldn't say a fair number. I haven't had any since 1987. That's one of my early days of working. I've been working on periodical cicadas for 45 years and one of the discussions was always, "Can you eat them?" Yes, you can. I don't eat them anymore. I've had them in things like stir-fries and batter-dipped and deep fat-fried and blanched and salads and things like that. They have a green flavor to me. They tasted like what I'd say, the closest thing that it reminded me of was cold canned asparagus, uncooked. That's what they reminded me of. As I say, it's a green flavor. I don't eat them anymore, because, well, how to put this delicately? They got me tenure. [chuckles]

Brian Lehrer: So, you don't have to?

Dr. Kritsky: I don't have to, but I owe my career to these insects.

Brian Lehrer: You don't want to kill them for food. I get it. At least you didn't say they taste like chicken.

Dr. Kritsky: They don't taste like chicken.

Brian Lehrer: Dr. Gene Kritsky, Dean of the School of Behavioral and Natural Sciences at Mount St. Joseph University in Cincinnati and author of many books on bugs, including Periodical Cicadas: The Brood X Edition. Thank you for all the information. That was really, really great.

Dr. Kritsky: I appreciate it. Thank you very much.

Brian Lehrer: Folks, here come the cicadas.

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