Brut X is expected to show up in about 18 states, said Dr. Kasson.

In the past, Brood X cicadas have been sighted as far as Michigan in the north, Georgia in the south, and Illinois in the west. Other states where they could arise are Kentucky, Ohio, New Jersey, New York, Pennsylvania, and Tennessee.

Brood X, also known as the Great Eastern Brood, has three epicentres in parts of the country. One will be in the Washington, DC area, including Northern Virginia and parts of Maryland. Another will be rooted in Indiana, and there will be a smaller one in and around Knoxville, Tennessee, said Dr. Kasson.

Large cicadas won’t appear in all states, said Chris Simon, professor of ecology and evolutionary biology at the University of Connecticut. “Some of them, it’s just a tiny little corner,” she said.

Other states, like Texas, get cicadas every summer, but those are usually annual cicadas or some other type, said Dr. Simon.

Because they feed on plants, cicadas can injure small trees and shrubs but do no harm to humans, said Dr. Kasson.

“They’re just very big and awkward,” he said.

If anything, Americans should consider themselves lucky to witness this phenomenon. “It’s really something to marvel at,” he said.

However, they can be annoying due to the sharp buzz they make when looking for friends.

“Men go on a rampage,” said Dr. Kasson, adding that in some areas with lots of cicadas the sound can be deafening. “It leads to this cacophonic shrill.”