HARRISBURG, Pa. (WHTM) — Cicadas are about to emerge in really big numbers, but whatever you do, don’t reach for the insecticide.

We’ve been getting reports of some cicadas already emerging from the ground in the Midstate. In the next few days, you’ll start to hear them and there’s not much you can do about it for the next few weeks.

It’s a once in 17-year experience.

“There is often an early emergence of a couple cicadas in this slow buildup, and then all of the sudden over one or two nights you’ll get most of them coming out,” said Dr. Michael Skvarla, assistant research professor of arthropod identification at Penn State University.

Skvarla says the Brood X cicadas have been underground this whole time feeding on sap from tree roots.

“They climb out of the ground, emerge as adults, only live for a couple of weeks as adults and the entire purpose is to find a mate, mate and then lay eggs and die,” Skvarla said.

The sound and sight of millions of cicadas might have you reaching for insecticide, but experts warn against it.

“Subsequently the bats and the birds are ingesting those chemicals and if enough toxins build up within those animals, they could die,” said Stephanie Stronsick, founder and executive director of Pennsylvania Bat Rescue.

Stronsick says the bat population is already declining.

“There’s a lot of really harsh chemicals out there that homeowners are spraying that could potentially affect them. But it also affects their dogs and their cats and their loved pets,” Stronsick said.

Plus, Skvarla says it’s just not worth it in the long run.

“You kill what cicadas you spray but then they just move in from next door and so pesticides, they don’t even make a dent in the population,” Skvarla said.

Other than small, newly transplanted trees, most can withstand the egg laying.

“They’re not effective at keeping cicadas off your trees anyhow,” Skvarla said. “It’s better to mechanically separate cicadas from your trees using netting just to keep them off the trees altogether.”

And though they will be loud and not pretty to look at, “Just allow them to do what they do and let our native wildlife do their due diligence in consuming them,” Stronsick said.