7 cicada species will emerge this year in rare event that hasn't happened since 1803

RALEIGH, N.C. (WTVD) -- Spring is around the corner and it's about to get much noisier in North Carolina.

Scientists warn billions of cicadas will emerge in the U.S. starting in April. It's a rare double brood emergence event that hasn't happened since 1803, when Thomas Jefferson was President.

"When the soil temperature about eight inches down gets to be about 64 degrees, they're going to start coming up," explained Dr. Clyde Sorenson, Professor of Entomology and Plant Pathology at North Carolina State University.

"They're just waiting right now," Sorenson added.

According to entomologists, there are seven different species of cicadas that will emerge in this event. Cicadas are in the same family as stink bugs and bed bugs.

Cicadas live in burrows until they're mature enough to surface and it's all to find a mate. The sound cicadas make is a mating call.

"The males are the ones that are making all the racket," Sorenson said. "The predominant species sounds like he's screaming 'pharaoh'. It's really high at a really high pitch. So, they say 'pharaoh' over and over and over about four hours a day until the right lady comes by."

Sorenson said three species surface every 17 years, the other four species surface every 13 years. But, once every 221 years, their emergence overlaps, and two broods come out at the same.

It's an event expected to happen this spring across the Southeast and Midwest.

"Millions, millions per acre," Sorenson explained about the emergence of the cicadas. "You'll look in the ground where they're coming up and it will just be pockmarked with holes, you know, maybe 15 or 20 per square foot in some places."

While cicada's mating call may be loud, they are harmless to humans. They don't sting or bite and are not poisonous.

Cicadas may be damaging to young trees, though, if female cicadas lay their eggs in one. To better protect a tree, the EPA suggests covering it with mesh or netting with 1/4-inch holes or smaller. You can also wrap the branches in cheesecloth to keep cicadas away but they aren't harmful to any flowers or fruit, they only consume sap to stay alive. Pesticides do not work on cicadas.

The next co-emergence of these broods won't happen for another 221 years in the year 2245.