Chicago, welcome to cicada season.
For the past 17 years, billions of periodical cicada spawn from Brood XIII have been living underground in the Chicago area, tapping into fluid from plant roots. And while they typically emerge in mid-May and June, some began to pop-up early, according to the Morton Arboretum in Lisle, Illinois.
"The periodical cicadas have been emerging for the last week and a half," Stephanie Adams, Plant Pathologist at Morton Arboretum in Lisle said Tuesday of Brood XIII, which will soon overspread across the entire Chicago area. "We found them both out here in our landscape and also in our East woods."
Once they burrow up from the ground, they'll head to trees and wooded areas for approximately four to six weeks, where they'll mate, lay eggs and sing.
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According to Adams, the emergence of the first cicadas comes about two weeks ahead of the historic average. It will continue to be sporadic, as soil temperature, mulch and turf grass all impact cicadas differently. For example, the soil is warmer near pavement, so cicadas in the those spots are expected to emerge quicker.
"Anything in biology always has a gradient," Adams continued. "So you always have early emergers and then you have ones that will emerge kind of late."
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Once they're out in big numbers, there's no escaping them -- and that goes for your trees, too.
How to protect your trees from cicadas
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Generally, cicadas are harmless, Adams said. They don't bite, and they don't have stingers, and they're beneficial to the environment. But they can cause damage to vulnerable and small trees and shrubs, Adams said.
According to Adams, young plants, between two to three years old, are the most vulnerable, and so are smaller plants, with branches less than two inches in diameter are at risk. They may not be able to recover from damage done by the female cicadas laying eggs, Adams said.
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“That damage is caused when the female starts laying her eggs,” Adams explained. “She has a specialized organ that will cut into the plants and trees and shrubs, and lay her eggs inside the thin bark.”
According to the Arboretum, one way to protect your trees and shrubs would be to use tulle as a wrap and protective barrier. Tulle material is specifically recommended because it is a breathable, and allows sunlight to penetrate the plant.
“You are looking for netting that is no bigger than quarter inch across, any bigger the cicadas can climb through and defeats the purpose of protecting them,” said Spencer Campbell, Plant Clinic Manager.
Homeowners are encouraged to start protecting their young plants as soon as possible, and to keep them wrapped through mid-June when the emergence ends.
What kind of trees are most vulnerable to cicadas?
According to the Arboretum, cicadas are "not particular," meaning they will use a variety of trees and shrubs as hosts.
"However, only very young trees or older trees that are unhealthy or stressed are at any risk," the Arboretum said.
The insects have been known to lay eggs in oak, maple, hickory, apple, birch, dogwood, linden, willow, elm, ginkgo, and pear trees, according to the Arboretum.
"Cicadas also may lay eggs in some shrubs, such as rose, lilac, and forsythia," the Arboretum said. "They tend to avoid conifers such as pine, spruce, and fir."
Arboretum records show that during the emergence 17 years ago, some of the plants most affected by the emergence were maples, cherries, ashes, hawthorns, willows, mountain ashes, oaks, pears, roses, privets, poplars, serviceberries, and beeches.
Do pesticides work on cicadas?
A post from the City of Lake Forest advised residents to "avoid planting young trees less than 2 inches in diameter," and to cover young trees with netting. The city also advised that residents to stay away from using insecticide.
According to the Environmental Protection Agency, pesticides are "generally ineffective at keeping cicadas away."
"So many cicadas emerge at once that more will inevitably move in," the agency said. "Spraying also doesn’t make sense because cicadas are generally harmless. Applying pesticides to control cicadas may harm other organisms, including animals that eat cicadas."
Can you limit the number of cicadas in your yard?
Frank Meek, a technical services manager at pest control company Orkin told NBC Chicago exterminators don't typically treat cicadas because they aren't a threat to humans, animals or property.
In addition, chemical treatments are generally ineffective against cicadas because of their short lifespan, Meek added.
"Cicadas are an important part of the food chain, and serve as meals for birds, moles, raccoons, and some frogs," Meek said. "It’s important for humans to leave cicadas alone so other animals can benefit from the food source."
Cicadas aren't considered pests, Meek said. But they have been known to fly into homes uninvited.
"Cicadas are strong but clumsy fliers and can accidentally fly into homes if windows and doors are left open," Meek said. "However, because cicadas cannot breed indoors, an infestation indoors cannot occur."
According to Meek, cicadas found in yards and gardens can be "gently" removed by hand. And though Orkin doesn't advise pest treatment around homes for cicadas, there is one extra layer of defense homeowners can take to keep cicadas further away, the company says.
"Homeowners can also prevent cicadas from making a home in their trees and bushes by wrapping the base in foil or barrier tape," Meek said. "This prevents cicadas from moving up the tree or bush to feed or lay eggs."
Still, experts say, it might not be worth the trouble. After all, there will be billions of them.
"You should definitely not try to remove them from an area with billions," said Allan Lawrance, associate curator of entomology at the Peggy Notebaert Nature Museum in Chicago.
While this year's emergence has just begun, it's expected to peak in the next few weeks.
"There's no stopping them," Allen Lawrance, associate curator of entomology at the Peggy Notebaert Nature Museum in Chicago said. "They're here. It's temporary, and there's really no escaping them."
