Apr 29, 2024 - News

It's time to hatch plans for cicada season, Chicago

Photo of a bug coming out of the ground

A cicada hiding under a log last weekend in The Grove in Glenview. Photo: Courtesy of Dave Odd

Parts of Illinois will be buzzing with this year's big cicada co-emergence, but for Chicagoans, it likely won't feel too different from the last time we saw the insects in 2020.

Why it matters: There's plenty of hype about a looming "cicadapocalypse," but experts and our Axios Visuals colleagues say there's no reason to bug out.

  • We've prepared a cicada season guide — whether you want to eat them, travel to see large swarms of them or just understand them better.

The big picture: When 13-year and 17-year cicada broods emerge simultaneously, it's called a co-emergence, and they're fairly common, occurring every 5-6 years.

  • But adjacent co-emergences, where the two broods overlap geographically as they do this year, are less common, happening every 25 years on average.

Zoom in: While Chicago will get one brood, the area that will see co-emergence starts about 90 miles south in Iroquois County, stretching down through DeWitt, Cole, Douglas and Champaign counties.

  • Good luck hearing those graduation speeches!
Data: USDA and University of Connecticut; Map: Will Chase/Axios

How it works: The ground, at an 8-inch depth, "needs to be 64 degrees after a rain to trigger the cicada emergence," ecologist and CEO of Landmark Pest Management Rebecca Fyffe tells Axios.

  • The ground in her Niles backyard recently checked in at 57 degrees, so she's predicting a mid-May emergence.

Threat level: Fyffe's been hearing from worried homeowners who want to use pesticides to prepare, but she tells them not to worry. Cicadas are an indicator of a healthy environment and the emergences help scientists monitor populations.

  • Cicada holes — about the size of your pinky — create helpful tunnels to funnel water and nutrients to tree roots.
  • When cicadas lay eggs in the smallest outer tree branches they do natural pruning, making trees "healthier, evidenced by more fruits and flowers after a cicada emergence," Fyffe says.
  • "When cicadas die at the end of the season, their bodies, which accumulate at the base of trees, provide important nutrients for the trees," she says.

Still, UMass ecologist Zoe Getman-Pickering tells Axios that the double emergence will have "massive, complex and cascading impacts on the ecosystem."

  • Case in point: Her team found that birds switch to a cicada-heavy diet during an emergence — causing the caterpillar populations they usually eat to double, causing knock-on effects like damage to caterpillar host trees.

Dig in: Cicada snacks aren't just for birds — just ask your dog or the thousands who bought cicada cookbooks.

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