Trillions of Brood 10 Cicadas to Emerge in U.S. After 17 Years Underground

Trillions of cicadas are set to emerge across 15 U.S. states this spring, as a colony of insects known as Brood 10 awakens from a 17-year-long hibernation.

The bugs, colloquially but incorrectly known as "locusts," are expected to appear for the first time since 2004 in Delaware, Georgia, Illinois, Indiana, Kentucky, Maryland, Michigan, North Carolina, New Jersey, New York, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, and Washington, D.C.

Having spent almost two decades underground in their immature "nymph" state eating tree root sap, the bugs will crawl out in mid-May to late June when soil hits 64 degrees Fahrenheit—likely after a sprinkling of warm rain. Once above ground, the insects will set about mating, the noise of which can hit 100 decibels, and lay their eggs before dying.

The cicadas are genetically programmed to emerge every 17 years in a "massive synchronous way," Michael J. Raupp, emeritus professor of entomology at the University of Maryland and a fellow of the Entomological Society of America, told Newsweek.

"Densities can be as great as 1.5 million per acre. So, between Georgia and New York there will surely be trillions emerging," he said.

They are believed to appear in such huge numbers to overwhelm their predators. This "strange survival strategy" is called predatory satiation according to Raupp.

Brood 10 includes the Magicicada septendecim species, characterized by its broad orange stripes and patch of orange between their eye; and the Magicicada cassini and Magicicada septendecula, who both have almost entirely black abdomens.

Although the idea of swarms of insects appearing from the earth may sound "unbearable and frightening," Raupp said, "this is a wonderful opportunity for millions of people to witness and enjoy a remarkable biological phenomenon in their own backyard that happens nowhere else on the planet, truly a teachable moment."

He said the bugs will not cause lasting damage to established trees, will not invade homes or "carry away cats, dogs, or small children."

Referring to the British TV station known for its wildlife documentaries and period dramas, Raupp said the return of Brood 10 "will be filled with romance in the treetops as males woo their mates, harrowing escapes from predators, gruesome death by a fungus that becomes an STD and turns cicadas into zombies—all the elements of a BBC special."

Raupp encouraged those who are scared of cicadas to learn about the bugs that are a "fascinating and unique part of life on planet earth."

He went on: "I advise them to seek counseling to help them through this time. For some, it may be time to plan a three or four week trip to some parts of the country where there will not be cicadas. For example here in my state of Maryland, several towns along our Atlantic coast will not have cicadas this year."

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A stock image shows a cicada sitting on a blade of grass in western North Carolina. Cicadas are due to emerge in 15 U.S. states this year. Getty