How to protect your trees from cicadas, according to experts at Chicago's Morton Arboretum

LISLE, Ill. (CBS) -- The massive periodical cicada emergence is inching closer and closer, and Chicago area residents are seeing signs in their own neighborhoods.

Illinois is the center of emergence, which means there will be more cicadas than anywhere else in the country. Two broods are coming—the Chicago area will see Brood XIII, which emerges every 17 years, while the southern half of the state will see Brood XIX, which appears every 13 years.

This means it is officially time to start preparing for the cicadas. Experts at the Morton Arboretum have been busy protecting hundreds of trees.

"They are definitely getting ready to emerge," said Morton Arboretum master arborist Stephanie Adams as she held a cicada nymph in her hand. "They are certainly very close to the soil surface right now."

The nymph is a living, crawling sign that the time is near. There are other signs too – which Chicago residents may find in their own backyards.

"You'll start seeing about half-inch emergence holes," said Adams.

This means precautionary measures are necessary—because while cicadas don't bite or sting, they can damage trees.

"They do cause damage on woody plants, and so we're working to protect some of our specimens here at the arboretum," Adams said. "Cicada damage is actually from the female laying her eggs in the bark."

Arboretum staff are wrapping up trees, and advise anyone who has trees on their property should take precautions too—especially those with young trees in their yards.

"They may want to consider protecting them, using a physical barrier," Adams said. "We recommend using a fine bird netting, or a tulle, which is the same material used to make tutus."

The arboretum will tutu about 500 trees this week.

"They can kill individual branches," Adams said. 

Adams advised that people looking to find out if they have a tree that needs to be protected can go to the Morton Arboretum plant clinic website, which has a bullet-point list of information.

She said there is no worry to worry about flowers, fruits, or veggies—as the cicada swarm will not go after people's gardens. Adams added that cicadas are actually good for the soil—and thus for lawns and wildlife.

Billions, possibly trillions, of cicadas will soon be buzzing around the Chicago area.

The last time the 13- and 17-year broods appeared in Illinois at the same time was in 1803, when Thomas Jefferson was president.

"I imagine we will start hearing them in the next two weeks or so," said Adams. "I would recommend people start netting their trees in the next two weeks."

Experts also advised that cicadas will not be emerging inside anyone's home. They are sustained by plant roots.

Once they are out, they will be around for about a month.