In a few weeks, a natural spectacle will take place in much of the United States – a spectacle that is not found anywhere else in the world. Billions of cicadas that have spent years patiently growing in total darkness will finally emerge, in perfect sync, for a shrill party in the sun.
17 years have passed and the periodic insects, also known as Brood X, are back.
When the world saw the cicadas for the last time, Facebook was brand new, cinemas were showing “Spider-Man 2” and the 2004 Olympic Games were underway.
Since then, they have been underground, eating.
“They are in the dark, they are eating roots, just living their best lives until the right time,” he said. Matt Kasson, an associate professor at West Virginia University who studies the cicadas and fungi that zombify them. “And that’s when they decide, you know what, it may be time to go up and find a partner.”
Beginning in late April or early May, when the soil is warm enough, billions of Brood X cicadas will be seen in a dozen states, stretching from Illinois to the west, Georgia to the south and New York to the northeast. The young cicadas, called “nymphs”, leave the ground with their claws and go up to take off their skin one last time and become adults. They will only have a few weeks to sing, mate and start the cycle again.
There are six species of North American periodic cicadas, all of the genus Magicicada. Three species live in a 13-year cycle and three for 17 years.
This year’s appearance is a group containing all three 17-year-old species: Brood X, so named because it was the tenth in an arbitrary nomenclature system designed in 1898 by entomologist Charles Lester Marlatt.
However, the group’s other name, The Great Eastern Brood, is much more descriptive.
Most of the more than 3,000 species of cicadas in the world do not make such a dramatic entry. Although it takes two to five years to grow, at least some adults of these annual species show up each summer, and in much smaller numbers.
Periodic species, in which they all consistently have the same extra-long life cycle that culminates in a mass emergency, are incredibly rare. With only one discovery recently, the exception – the 8-year-old train millipedes in Japan – cicadas are the only insects that have evolved to live that way.
Why? For Magicicada, part of the answer is under layers of ancient ice.
“During the glacial periods [of the past few million years], we think they probably extended their life cycles, because the growing season was too short to complete development in their previous time, “he said. Chris Simon, a cicada researcher and professor at the University of Connecticut.
The second reason has to do with your above-ground survival strategy. They don’t have one.
In the natural sciences, it is called “satiety of the predator”. After a certain point, even the most hungry predators will no longer be able to eat physically. But without a large synchronized group, the plan falls apart.
“It favored the individuals who went out together, because they survived better,” said Simon.
Not all nymphs grow at the same rate. For example, someone who eats a tree that has had a bad year will need more time. But if all the cicadas wait for the full 17 years, this will allow the unlucky ones to reach and increase the numbers of the group.
“So there is a kind of feedback loop,” said Simon. “If they leave in other years … they will be eaten by predators. And they will also not be able to find mates.”
Despite their seemingly infinite number, periodic cicadas are far from invincible.
Two litters, XI and XXI, have become extinct and a third, Litter VII, is currently in decline. Cicadas need trees to lay eggs and feed themselves, so deforestation is devastating for them.
A warmer climate – and a longer growing season – can also favor a shorter life span, causing species from 17 years old to permanently change to 13 years old, as happened with midwestern species. M. neotredcim.
Periodic cicadas are a crucial part of the ecosystem. Nymphs are the food of animals that live underground, and adults feed all carnivores in the region. Even the many uneaten cicadas return to the trees – as they decompose. They become “basically fertilizers,” said Kasson.
Simon and Kasson said they expect people to decide to venture out and watch Brood X while they have a chance.
Thousands of small animals buzzing can be overwhelming or uncomfortable for some. But cicadas are harmless and, according to Simon, a little goofy.
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“Cicadas are very kind; they don’t bite or sting. They are not attracted to people; are attracted to noise, ”she explained.
For the curious of the cicada, it is easy to get involved.
More information about Brood X and periodic cicadas in general can be found on the Cicada Mania website and on the University of Connecticut cicada home page. Simon’s colleagues also developed a smartphone app, Cicada Safari (available for iOS and Android), which allows anyone to be an amateur entomologist.
By submitting pictures of cicadas and recordings of their songs, the public can help map the reach of Litter X, track its population and discover first-hand what Simon calls “one of the seven wonders of the natural world of insects”.