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PITTSBURGH (KDKA) – Get ready, a massive swarm is coming in just weeks.

The 17-year cicadas are coming again, millions of them, with their unnerving red eyes, orange wings and cacophonous mating song that can drown out the noise of passing jet planes.

“They will wait until the temperature of the soil is roughly 64 degrees,” he says. “So in the past that has been mid-May and they’ll be out all through June.”

Experts say that a large brood of cicadas is expected to emerge from the ground this spring after 17-years, and Southwestern Pennsylvania will be right in the center of it.

“In some areas, you can get as many as a million and a half individuals per acre, when they’re really dense,” Bob Davidson, invertebrate zoology collection manager for the Carnegie Museum of Natural History says. “The brood that is coming out this year has all three species of periodical cicadas.”

Davidson says annual cicadas come out every year, those are the ones you’ll hear in July and August.

“Periodical cicadas, the ones that are coming out this year, will have massive numbers,” Davidson says. “Most of the annual ones are bigger and greener and don’t have the orange patter on them, and they’ll be out later in the year.”

The 17-year cycle cicadas that will be coming out this spring only occur in Southwestern Pennsylvania, the eastern edge of Ohio, and the tip of West Virginia.

“They’ll be in Allegheny, Washington, and Westmoreland counties pretty heavily, even up to Clarion and Indiana counties,” Davidson says.

“You’ve got to make sure you all come out together, so you can find each other, mate and reproduce,” said John Rawlings, and entomologist at Carnegie Museum.

In reality, though, cicadas are harmless and actually good for the environment.

Their egg-laying in the trees is a natural pruning that results in increased growth, their burrowing aerates the ground, and their decaying bodies add nutrients to the soil.

However, they are a little loud.

In 2016 a brood of cicadas emerged in Washington, Westmoreland and Greene Counties.

“It’s a pretty phenomenal evolutionary trick to hide for 17 years, and then all come out at once so your enemies can’t eat all of you,” said Lee Stivers of Penn State Agriculture Extension.

If you’re in an area that’s been invaded and are concerned about your trees. Experts say most larger trees can sustain the onslaught, but if you have a small tree you’ve planted in the past year, you should take some precautions.

“Cover the tree with insect netting,” said Stivers.

Throughout the five counties of Southwestern Pennsylvania, they find each other. In no time, the female is digging ruts in tree limbs and depositing eggs, which is where the damage comes in.

Adult cicadas exist only to mate and then die. Birds, other insects and fish typically prey on them.