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An expert says that no one alive can experience this phenomenon again: a remarkable plague that only occurs once every 221 years has begun.
Washington – A phenomenon that only occurs in this combined form every 221 years is not only a concern of science these days. Millions of people in the USA also have to deal with it, whether they want to or not. Some people suffer from the disgusting sight or just the noise. Others, however, are fascinated.
We’re talking about a monstrous plague of cicadas. The animals are loud, sexually aroused and roam through forests and suburban gardens in the USA for about a month. These days, countless cicadas are crawling out of the ground where they have lived as larvae for years. This year, for the first time since 1803, two events coincide: both the cicadas that only appear every 17 years and those with a 13-year rhythm emerge from the ground.
Cicadas in the USA: Why do they always come at prime intervals?
There are more than 3,000 species of cicadas worldwide. The small insects spend most of their lives as larvae in the soil. Only when they are fully grown do they come to the surface of the earth to mate. For many cicada species this happens annually, for others only every 13 or 17 years. Scientists have long puzzled why cicadas emerge at prime number intervals, but there is no obvious evolutionary biological explanation for this.
Entomologist Zoe Getman-Pickering is also puzzling Mirror-Interview – and explains what possible approaches there are in science. “One theory is that cicadas evolved during the ice ages. Back then, the plants that survived grew very slowly. “That’s why the cicadas have developed this very slow way of life,” says the expert. “Another theory is based on their sheer numbers. If a billion cicadas suck the sap out of the trees, it can damage the trees. But if the tree dies, the cicadas also die. So you need to absorb enough sap to grow but not kill the tree. Hence the slow growth.”
The spectacle is accompanied by a deafening noise from the many chirping male cicadas ready to mate. The Newberry, South Carolina Sheriff’s Office recently reported on Facebook: “There have been a few calls about a noise in the air that sounds like a siren or a howl or a commotion.”
Cicadas in the USA: They cause incredible noise – “Let them disappear”
It gets really loud! “In areas with high concentrations, when all males chirp at the same time, it can be up to 110 decibels loud, which is close to the noise level of an aircraft turbine,” explains entomologist Floyd Shockley from the Smithsonian Natural History Museum in Washington to the German Press Agency. “When I’m in an area with a high concentration of cicadas, I often use earplugs because that’s close to a level where hearing damage occurs.” Experts have compared the chirping of a single male cicada to the noise of a lawnmower or motorcycle.
“Let these cicadas disappear,” writes a user on X about a video whose authenticity cannot be confirmed. “They are currently louder than a rock concert.” Other, unconfirmed recordings also show large numbers of the animals. “The cicadas are here! Wow!”, it says about this:
This year is particularly significant because there will be two huge swarms around the same time, emphasizes researcher Shockley. This combination, including probably a small geographical overlap between the swarms, last existed 221 years ago, i.e. in 1803. “No one alive today will experience this again,” he emphasizes.
The next generations of the so-called Brood XIX and Brood XIII will hatch in the years 2037 and 2041, respectively. But the 2024 combination is extremely unusual. The largest swarm of cyclically occurring cicadas, the so-called brood XIX (Roman 19), slumbered underground for 13 years, brood XIII (13) for even 17 years. At that time, George W. Bush was still president in the USA, and 2007 was also the year in which the first iPhone came onto the market.
More than a trillion cicadas expected in the US
Expert Shockley assumes that over a trillion cicadas are likely to hatch in the 17 affected US states from April to June, i.e. more than 1,000 billion. “It will definitely be more than a trillion, maybe several trillion.” Researchers at the University of Connecticut are also predicting several trillion cicadas this year. The insects will settle primarily in forest areas, rather than on agricultural land or in urban green spaces. If you assume about a trillion cicadas and chain the insects, each two to three centimeters long, together, the result would be an almost endless chain. “It would reach to the moon and back several times,” Shockley estimates.
“When they come out, they come out in large numbers,” says entomologist Gene Kritsky of Mount St. Joseph University. He has developed a cicada safari app that helps amateur scientists contribute to better research into the red-eyed insects. Kritsky also explains the appeal of cicadas by the fact that people can often remember exactly how they appeared in flocks before and associate them with personal memories.
And besides, it’s nice to see a prediction come true. “That’s what science is all about: you put forward a hypothesis that leads to predictions,” says the entomologist. And if these predictions come true, it would be “something valuable in these times when some people believe they can disregard science.”
Cicadas in the USA: “The sheer number of them hatching is the strategy for survival”
Biologist John Lill from George Washington University explains the fact that cicadas appear in huge flocks because the individual animals are practically defenseless and easy prey for birds, turtles, raccoons and other predators. This is also how expert Getman-Pickering explains it in Mirror: “The sheer volume in which they hatch is the cicadas’ survival strategy. In these masses they cannot all be eaten by birds, squirrels, dogs or raccoons.”
Lill and colleagues recently published a study in the journal “Science” about the effects of cicada swarms on the ecosystem. In 2021, the appearance of Brood X in the capital Washington led to an increase in insect-eating birds. Since the birds liked to eat their fill of the cicadas that appeared in large numbers, more caterpillars remained. This in turn led to more oak shoots being eaten by caterpillars.
Other new research found that oak trees produce a particularly high number of acorns exactly two years after cicadas migrate. This means there are more mammals that feed on the acorns, such as wild boars. And this, in turn, increases people’s risk of developing tick-borne Lyme disease. This shows that the ecological impact of the appearance of cicadas can last years after they disappear, says Lill.
On the other hand, cicadas are also heavily dependent on environmental influences. According to evolutionary biologist Chris Simon of the University of Connecticut, climate change threatens to disrupt cicadas’ internal clocks. She expects “more 17-year cicadas to permanently become 13-year cicadas.”
The changes in nature caused by humans sometimes also have positive effects on cicadas. The well-lit trees in suburban gardens provide them with optimal conditions for laying eggs. When the adults die, cicada larvae hatch from the eggs, fall from the trees and burrow into the ground, starting the cycle again.
![A cicada near the University of North Carolina at Chapel Hill on May 1](https://www.merkur.de/assets/images/34/557/34557524-eine-zikade-nahe-der-university-of-north-carolina-in-chapel-hill-am-mai-2sxKZ6f9KaBG.jpg)
Cicadas in the USA: The last big wave was in 2023
The last major wave of cicadas occurred in 2021, when brood X hatched. In 2024, this is expected to spread from the southern US states to the north and to the east coast. Things should really get going in Illinois in the north of the USA by June at the latest: Brood XIX will spread in the southern part of the state, while swarms of the smaller Brood
According to experts, there could be more than a million cicadas in the area of about half a football field in some areas. “In parts of Chicago, the last time Brood XIII hatched, they had to clear streets and sidewalks of dead cicadas with shovels,” says Shockley. The Northern Lights over Germany are currently providing fascination on this side of the Great Pond. (AFP/dpa/lin)
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