Mark Bennett: Cicada influx of 2024 may be worth east-central Illinois road trip

May 2—I wouldn't call myself an entomology buff.

Interloping stink bugs and spiders get immediate evictions in our house, and I can't pretend to be fond of buffalo gnats or mosquitoes. So, there's that.

Still, the idea of an epic insect occurrence intrigues me enough to make a road trip. In 2021, the once-every-17-year emergence of the cicada group Brood X prompted closet entomologists — yes, there is such a hobby — to travel and explore forests, old cemeteries and state parks to see, hear and photograph those big-winged, bug-eyed insects from Indiana to the East Coast. Alas, they didn't emerge in overwhelming numbers, as anticipated, in the Terre Haute area (except for some hotspots), so my wife and I traveled to the Indiana University in Bloomington to check out the bugs invading IU.

(OK, we actually went to Bloomington for lunch, but we did stroll through the campus and found lots of cicadas on virtually every outdoor surface.)

The thought of experiencing a natural phenomenon that wouldn't occur again until 2038 fascinated me.

Now, an even rarer entomological event is about to unfold nearby in Illinois.

First, some basic Entomology 101. Annual cicadas live and eat underground for two years, and groups of them emerge every year to mate and eat tree sap for a couple months and, well, die. Periodical cicadas spend 13 or 17 years underground before emerging as a group or brood.

Almost every year two different broods of periodical cicadas emerge simultaneously. Two large cicada groups — the "Great Northern" Brood XIII (every 17 years) and the "Great Southern" Brood XIX (every 13 years) — will co-emerge this month through 16 states. That includes the Illinois counties of Edgar, Clark and Crawford, according to the U.S. Forest Service map.

In some cases, especially near the western and northern borders of Edgar County, the Great Southern and Great Northern broods will emerge in the same spots. The male cicadas' mating buzz could reach 90 to 120 decibels — about equal to that of a chainsaw or a butt-kicking rock concert.

The last time those massive broods co-emerged, Thomas Jefferson was president.

So, are they road trip worthy? Oh yes, says bug expert Marianne Alleyne. "It's a great day trip," she said.

Alleyne calls the cicadas' co-emergence "pretty amazing."

"I try to stress to people, this is a really cool event that rarely occurs," Alleyne said Wednesday by phone from the University of Illinois. She serves as assistant professor of entomology at the U of I campus in Champaign. Alleyne also served in 2023 as president of the Entomological Society of America — which includes 7,000 "researchers, teachers, extension service personnel, administrators, marketing representatives, research technicians, consultants, students, pest management professionals, and hobbyists," according to its website.

They're energized. Alleyne's brother-in-law jokingly tells her, "It's kind of like your Woodstock, isn't it?"

It is. As Alleyne puts it, "Insects are pretty special."

That interest led her to travel to Bethesda, Maryland, three years ago to see peak influxes of the 17-year Brood X cicadas. "It was amazing," she recalled. "Whole trees were covered with cicadas. We'll have that here [this month], too."

A dual emergence of the Great Northern and Great Southern periodical cicada broods won't occur again until the year 2245. That kind of sounds like a '60s song.

Thus, entomological tourists may be visiting places like the fringes of Edgar County.

"This is a really big deal," Alleyne said of the entomology world. "We are very excited. In Illinois, we were envious of our colleagues in the Eastern United States [in 2021], but now we get to experience it."

The cicadas will emerge once the soil temperature reaches 64 degrees. Alleyne expects that will happen in east-central Illinois in the next couple weeks. Initial signs of the cicadas climbing to the earth's surface will be their escape holes beside the bases of trees, according to a U of I entomology report. Shells will accumulate in those spaces, after some cicadas shed their exteriors.

Unlike annual cicadas that live two to three months, these periodical Brood XIII and XIX cicadas will exist as adults for a mere two to four weeks. They'll seize the day, so to speak, mating, gorging on tree sap and laying eggs — duties that lead to the next cycle of cicadas. They'll chew slits into tender tree branches to lay those eggs. Adult trees may brown from the cicadas' intrusion, but should survive and ultimately benefit from it all in coming years, thanks to the nutrients in the insects' carcasses, Alleyne said.

"It looks bad, but if it's an adult tree, they can withstand [the cicadas]," she said.

Young or newly planted trees could be damaged and may need to be covered in a protective netting.

And then there's the noise. "They're quite loud," Alleyne said. "The male cicadas make a sound to attract the females."

It apparently works exceedingly well. Trillions of those cicada broods about to emerge. The males generate the rising buzz by expanding and contracting a membrane called a tymbal.

The reasons why the periodical cicadas stay underground for 13 or 17 years before they emerge together remains a bit of a scientific mystery. The mass arrival may be an effort to fend off extinction by the bugs' many predators, Alleyne explained. There's just too many to kill them all.

With that in mind, average folks are advised not to try to kill cicadas with pesticides. "There's not much you can do about them, because there's so many of them," Alleyne said.

Instead, it might just be time to embrace our inner bug-geek, and spend an afternoon wandering through the Illinois countryside.

Mark Bennett can be reached at 812-231-4377 or