Science

“It’s Pretty Much Death”

An entomologist explains what will happen when the Brood X cicadas emerge.

A cicada on a leaf
A close-up of a Brood X cicada, emerging soon. Getty Images Plus

In May, a swarm of billions of cicadas known as Brood X will emerge from the earth after hibernating for the past 17 years. Their song—which can be as loud as a  rock concert if you get too close—promises to ring across the nation as the insects hatch in 15 places, including Indiana, New Jersey, Long Island, Pennsylvania, and D.C.  People are having a hard time reconciling how to deal with both still-ongoing pandemic and a cicada storm, which has the potential to ruin alfresco gathering plans. Summer outdoor weddings are already being moved indoors in preparation for the onslaught, with families just counting on guests being vaccinated. “My greatest fear is someone props a door open for a delivery and a cicada gets in,” the mother of one bride told the Wall Street Journal.

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To understand how to come to terms with the cicadas, I spoke to Jessica Ware, an entomologist and assistant curator at the American Museum of Natural History who loves cicadas so much that she told me she was wearing cicada wings as earrings during our interview. She explained why Brood X is going to descend on us now, of all times, and how it’s basically just promising to kick off spring with the sounds of (bug) sex. Our conversation has been condensed and lightly edited for clarity.

Elena DeBre: OK, so what is Brood X?

Jessica Ware: There are annual cicadas that come out every year, and then periodical cicadas either come out every 13 years or every 17 years.

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What happens is females and males mate, and the females lay eggs, the eggs hatch, and the larvae drop down to the ground, and then burrow on underneath the soil. And they live underneath the soil for 17 or 13 years, feeding on plant roots, on tree roots. Then, when the ground turns 64 degrees, after either 13 or 17 years, the cicadas come out of the soil in this giant swarm. Brood X is one of these 17-year emergences.

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Why do they emerge in such a large group?

It’s called a “satiation strategy.” The idea is that there’s so many of you that your chances are better than your siblings’, that the other cicadas around you will be eaten by birds or other animals, and you yourself will survive to reproduce and lay eggs and have your genes go into the next generation.

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Researchers think this brood kind of behavior—where you have kids every 13 or 17 years instead of annually—came on the scene around 500,000 years ago. But before that, for like 4 billion years, it was just regular annual cicadas.

Why every 13 and 17 years? Do cicadas just love the odd numbers?

There are 12 broods that come out every 17 years, and there are three broods that come out every 13 years. They think maybe the 13-year broods began because some cicadas miscalculated the time and accidentally came out four years early. But now those broods always come out every 13 years. Researchers wonder whether, with climate change, the 17-year broods will start coming out early too.

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Why are these cicadas called Brood X?

The early European entomologists that were studying this phenomenon of cicadas, or “the plague of locusts,” as they called them, came up with a numbering system using Roman numerals. But the numbers are relatively random.

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What will happen once Brood X emerges?

Well, it’s pretty much death. They emerge. Then, the males have to sing—there’s actually three different species in Brood X and they each have a species-specific song. So the males sing, the females listen to a particular song that tells her the males are the same species as her, they mate, and then as soon as intercourse is completed, they pretty much die. The female lays her eggs on the bark or branches of trees, and the adults die. And from that point onwards, it’s just nymphs—what they call cicada babies—in the story, until 17 years later.

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So that loud cicada chirp we’ll be hearing is really a mating song?

Yeah, so males can be 100–120 decibels. That can be really loud. They have this organ called a tempo organ that vibrates and makes this noise, and the frequency and duration are orchestrated to allow females of one species to find a male of that same species.

Are there any other insects or animals that make any comparable sounds? Or are cicadas the loudest?

Crickets and grasshoppers also make calls. The annual cicadas have a loud call. But I think what’s so striking about the periodical cicadas is that there are a lot of individuals. The sheer number of males that are calling at one time makes it so the sound seems infinite.

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How long will we be hearing this sound echo through the eastern U.S.?

For a least a few days, if not a week or two. They’re going to start emerging around May 13. But it’s a little bit fuzzy when the last one will stop calling and die.

Why do they have to be so loud?

They have a relatively small window to find a mate. So the strategy is to be loud so that females can hear you from two or five trees over.

Once the cicadas emerge, do they travel to different states or stay put? 

There are 15 broods that make up Brood X, and they’re going to be coming out in the eastern United States. And they’re just going to stay where they emerge. So if they emerge in Princeton, they’re going to find a mate in Princeton, and they’re going to die in Princeton.

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I think a lot of people are dreading the emergence of the cicadas because we’re just dealing with so much already this year. What would you say to them?

This is something we should be celebrating. It’s really exciting. It’s a biological phenomenon that’s interesting but also a bit a like a time capsule. If you have a baby today, they’ll be graduating from high school when this brood is next out, which I think is exciting to see. And these cicadas are a great resource. If you’ve got some great birds in the neighborhood that are hungry, this is going to be a giant supper for them.

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