LISLE, Ill. (WLS) -- Billions of cicadas are starting to appear as the double brood emergence begins in Northern Illinois, and protecting young trees is of utmost importance.
Scientists are still learning about these little critters because they only have a short opportunity to study them every 17 years. Nymph cicadas are some of the earliest to emerge from a few inches underground, and their fans have been waiting patiently.
"I don't know what to expect," said Medinah resident Claudia Beckmann. "I think we're gonna have a lot more than 17 years ago."
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In a few days, the nymph cicadas will shed their exoskeleton, and will be free to mate. That's when the legendary sound begins as the males try to get the attention of the females.
"In 10-15 days after they emerge, they'll start mating and laying their eggs. So you'll start hearing the noise in the next week or so," said Stephanie Adams of the Morton Arboretum.
And that's why the arboretum's tree experts say it's important to protect your sensitive, young trees and shrubs with netting.
Female cicadas lay eggs by cutting or burrowing into the underside of small tree branches that are up to an inch in diameter, laying 10 to 20 eggs in each cut. And they lay up to 600 eggs in total.
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"We recommend you protect any tree you cannot stand to lose. It's cheaper to protect them than to lose it," said Spencer Campbell, Morton Arboretum.
They have already started putting up netting at the Arboretum, where they plan to protect about 500 trees and shrubs.
Arboretum experts recommend leaving the netting up through mid- to -late-June, and using netting or fabric with holes no bigger than a quarter inch to keep the cicadas out.
"You want to use material that breathes nicely, doesn't trap moisture in the netting, and also allows light to penetrate," Adams said.
After spending the last 17 years underground, these little guys have a lot of work to do in a short amount of time. Their life expectancy is only three to four weeks.