Return of the cicadas: Trillions of the noisy insects are expected to emerge in 2021

Remember the millions of cicadas that were expected to emerge in 2020? Well, a larger brood of the insect is coming next year.

Between May and June, various American states saw millions of cicadas emerge after spending nearly two decades underground.

These cicadas, classified as magicicadas, are a genus of insects that have an internal clock that signals them to emerge from the ground every 13 or 17 years.

This year, the periodical 17-year cicadas, Brood IX, emerged in record-breaking numbers. In May researchers at Virginia Polytechnic Institute and State University said an estimated of 1.5 million cicadas per acre could emerge in North Carolina, Virginia and West Virginia.

According to Eric Day, an entomologist with the university, there aren’t any exact numbers as to how many Brood IX cicadas emerged this season because of pandemic-related restrictions on field reporting.

“We don’t have any concrete numbers or sampling because of COVID-19,” he told in a phone interview. Nonetheless, he said the cicadas were still heard loud and clear by researchers and locals observing from their homes.

In 2021 however, researchers will be given a second chance to see an even greater emergence as Brood X gets ready to come out.

“I call it one of the seven wonders of the insect world,” said professor Chris Simon, who teaches ecology and evolutionary biology at the University of Connecticut.

Simon and her colleagues are among many biologists and scientists across the world looking to uncover the mystery of why cicadas emerge in specific time frames, though many have speculated it is to avoid predators.

The spectacle with Brood IX is that these 17-year cicadas have three species, which Simon said can appear as a large, medium and small species. For four weeks these species began emerging throughout the U.S., calling to each other in song.

“Each of them have a very different song and the songs are what keep them reproductively isolated so that they stay three different species,” she said in a phone interview with

On average they spend four weeks in any one place, but this year Brood IX stayed around for a month and a half.

While Brood IX is mainly gone now, Simon said there are four-year cicadas that are still emerging in parts of Chicago, a surprising turnaround for an area not known for the noisy insect.

“We were surprised by how big the emergence was in Chicago and how long it lasted because usually these four-year early emergences and four-year late emergences are very brief and there’s not very many cicadas so they’re only out for a week but because of climate change, we think this is happening more and more so,” she said.

According to Simon, there were likely hundreds of thousands in Chicago and they were reported to have been very noisy, indicting eggs were likely being laid.

While it is still unknown how many cicadas from Brood IX actually emerged this year, Simon said tools are being developed to help provide an estimation.

Simon aided in developing the crowd-sourcing app called Cicada Safari, which is used to collect photos of cicadas in the locations they’re emerging. The app was developed by Gene Kritsky, the dean of behavioral and natural sciences and professor of biology at Mount Saint Joseph University in Ohio.

With the app, anyone can upload an image of a cicada and pinpoint the exact location. The image is sent to the staff at the Ohio university and reviewed to detect the species and determine the quantity of these insects.

This year Simon said the app was able to collect almost 9,000 records of all species, including Brood IX.

She said the app is instrumental to their research and encourages people to participate in the quest to learn more about the insect.

“In the past they only lasted for a few days but now that we have people all over the Eastern U.S. helping us. It’s much easier to find them, so we’re getting huge numbers of records of this phenomenon and getting a better picture of it, seeing that it’s very widespread.”

As for 2021, Brood X is expected to reach various populated areas in the U.S. but the main regions that will see the most activity will be Virginia, Marlyand, Washington, D.C., Baltimore, New Jersey and even parts of Pennsylvania.

“Next year there’s an enormous brood coming out, which is Brood X, one of the biggest 17-year broods,” she said. “More than millions, there will be trillions. Nobody has really estimated the exact number because there are many hectares and acres of these things. The highest numbers that have been estimated are about 1.5 million per acre.”

While it is only speculation at this point, Simon said she believes climate change is the likely factor that is causing these late and early emergences.


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