Environment. Why the United States will be invaded by billions of cicadas


This is the worst cicada invasion in the last 200 years. In the coming weeks, billions of cicadas, noisy and ready to mate, will invade America’s forests and suburban suburbs. In this large family, which includes more than 3,000 species of insects worldwide, two groups of cicadas will frolic in the same place at the same time. The last time this happened, Thomas Jefferson was still president EThe United States purchased Louisiana from France.

Most of these winged insects spend their lives underground, in larval form. They emerge as adults to molt and reproduce. Some appear every year, while others, called “periodic” cicadas, appear more rarely. This year it is the case of group XIX, which is formed every 13 years and which started already in Estates of North and South Carolina, southeast of EUnited States. It will be followed by Group XIII in the Midwest, which is created every 17 years. In central Illinois, these two groups of cicadas could be present in the same location.

What are the environmental consequences?

Without much defense, “periodic” cicadas rely on their numbers for the survival of the species. Thanks to the hordes that are increasing at the same time, their predators – birds, foxes, raccoons, turtles – quickly become full, explains John Lill, a professor of biology at George Washington University. As a result, they turn away from their next prey. A study recently published in the journal proved this Science : The emergence of a group of cicadas in Washington in 2021 led to an increase in caterpillars, neglected by birds that targeted cicadas. As a result, consumption of young oak shoots by caterpillars increased.

Other research shows that the years when oak trees produce the most acorns always follow two years after cicada emergence. The more acorns there are, the more the populations of mammals that feed on them grow, the greater the risk of Lyme disease in humans. This phenomenon “shows that there are potentially longer-term ecological impacts that reverberate years after the cicadas appear,” believes John Lill.

And global warming is unlikely to help the situation. According to Chris Simon, a researcher at the University of Connecticut, an increase in the planet’s global temperature could disrupt cicadas’ internal clocks. Extending the growing season of plants provides cicadas with more and faster food. “My guess is that more 17-year-old cicadas will turn into 13-year-old cicadas,” she said, “and eventually the trait will be assimilated genetically.” According to John Lill, it’s hard to know what this means for the species in the long term.

” This has value in a time when science is discredited”

At this moment, the unique shrill sound of mating male cicadas begins. “We have had several calls regarding what sounds like a siren, wailing or roaring,” the Newberry (S.C.) Sheriff’s Office said on Facebook this week. The presence of a large number of cicadas is also an opportunity to contemplate nature up close.


“When they emerge, they do so in large numbers, which excites parents and children,” says entomologist Gene Kritsky of Mount Saint-Joseph University, who developed the app so anyone can collect data on the creatures. “That has value at a time when some people are trying to discredit science,” recalls the researcher.

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