PITTSBURGH (KDKA) — It’s a song 17 years in the making.

Cicadas live underground for 17 years, feeding off tree roots. Then, when the time is right, the whole population emerges.

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The cue to surface comes from the weather.

“Here they are normally out in May, but if we have a warm rain and some hot weather they could be out in April,” said Bob Davidson, Carnegie Museum Collection manager.

This is just the kind of weather western Pennsylvania has been having, and timing it perfectly is crucial for the cicadas.

“You gotta make sure you all come out together so you can find each other mate and reproduce,” Davidson said.

So they climb the nearest tree, find a good spot, and start “chattering” for a mate. The sound can be ear splitting.

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“You can get up to a million and a half in an acre that is infested,” Davidson said.

Throughout the five counties of Southwestern Pennsylvnaia, 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.

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“Because the twig is injured, the leaves that are outside from the trunk outward turn black and die,” Davidson explained.

In 1999 the Carnegie’s John Rawlins went out cicada hunting, with the car windows wide open.

“Just keep your ears open as you’re coming up 79, and all of a sudden you’ll hear a roar and find an exit and start picking cicadas,” Rawlins, an entomologist, said.

Feel free to eat them if you like, straight off the tree.

“They are fat and kind of plasticy with all sorts of nutrients,” Davidson said.

Rawlings was more specific with his description.

“It tastes like a bad batch of rice crispies after a long night of heavy drinking.”

But it’s a limited time offering. Within a month the process is over, the parents are dead and the nymphs are heading below ground to start the cycle over again.

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Brood V, the next generation, will emerge in 2033.