Bugging Out: Billions Of Cicadas From 2 Broods To Arrive In IL

ILLINOIS —Billions of periodical cicadas from two broods and a rare crossover of two varieties of the insect will emerge this spring in a rare, synchronized event that hasn’t happened since 1803.

University of Illinois Extension officials say it will be an especially noisy spring in Illinois, with emergence of both the 17-year cicadas in Brood XIII, known as the Northern Illinois Brood, and the 13-year cicadas in Brood XIX, the Great Southern Brood. A tiny bit of southeast Iowa will also see both broods.

Brood XIII cicadas also appear in Wisconsin, Indiana, Ohio, and a bit of Michigan.

Brood XIX cicadas will be found in a much larger area that touches 15 states: Alabama, Arkansas, Georgia, Illinois, Indiana, Kentucky, Louisiana, Maryland, Missouri, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, and Virginia.

Cicadas spend most of their lives underground as immature nymphs, who surface en masse every 13 or 17 years.

“It’s like a graduating class that has a reunion every 17 or 13 years,” Gene Kritsky, professor emeritus of biology at Mount St. Joseph University and author of “A Tale of Two Broods: The 2024 Emergence of Periodical Cicada Broods VIII and XIX,” a book about this year’s dual emergence that was published earlier this month, told NBC News

For insect geeks, 2024 will come close to nirvana. Jonathan Larson, an extension entomologist at the University of Kentucky, described it to NPR as the insect world’s “spectacular, macabre Mardi Gras” celebration that will occur from late April through June.

It’s spectacular not just because two broods are emerging in the same year, but because cicadas are true marvels of nature. An extraordinarily long life cycle, the longest of any insect on the planet, is part of an evolutionary strategy that has allowed the species to survive for 1.8 million years, or from the Pleistocene Epoch.

It’s macabre because cicadas have an almost singular purpose after their noisy emergence — to go forth and multiply to ensure the species continues — and then they die in four to six weeks. By July 1, they should be gone entirely.

Cicadas should start tunneling toward the surface when soil temperatures reach about 64 degrees. In Illinois, that should be sometime around late May, University of Illinois officials said on the extension office’s website.

The Northern Illinois brood has a reputation for being the largest emergence of cicadas anywhere. According to research done by entomologists Monte Lloyd and Henry Dybas at the Field Museum in Chicago, a 1956 brood of Northern Illinois cicadas produced 1.5 million cicadas per acre.

In upland sites, they recorded 27 emergence holes per square yard, translating to about 133,000 per acre. This number is more typical of emergence numbers but is still a tremendous number of insects. For comparison, a city block contains about 3½ acres, the researchers discovered.

The last periodical cicada emergence in 2021 was a pop culture phenomenon, with a cookbook’s worth of cicada recipes and advice from veterinarians on what dog owners should do if their pup eats and hacks up a cicada. Cicadas are a fast-food buffet for copperheads, too.

And who can forget those cicadas who got tangled up by the same psilocybin fungus found in “magic” mushrooms and had frenzied sex until their genitals fell off? They were so messed up they didn’t even know it and continued to try to copulate after the important parts had fallen off, according to researchers at the University of West Virginia.

Here are seven things to know about cicada emergences in 2024:

What Are Periodical Cicadas?

Periodical cicadas are considered “true bugs,” unlike most of the insects that are referred to as bugs, according to the National Wildlife Federation. They are about an inch long and have a three-inch wingspan.

They are known for their extraordinarily synchronized lifespan, emerging every 13 or 17 years, depending on their species. They spend all but a few weeks of their long lives burrowed beneath the soil and feeding on fluids from plant roots. When spring temperatures arrive, they emerge from the soil and complete their final molt into adulthood. Each individual member of a given brood emerges within weeks of each other.

There are annual cicadas, too. They live about two to eight years, but their life cycles are not synchronized. They’re called annual cicadas because some emerge from the ground every year.

What Is A Brood?

Groups of cicadas that emerge in the same year are called broods, made up of multiple species of cicadas that merge on the same cycle. The Northern Illinois Brood has three species of cicadas, while the Great Southern Brood has four.

Broods are assigned Roman numerals in a tradition established by Agriculture Department entomologist Charles Marlatt in 1893. The 17-year cicadas that emerged that year were known as Brood I, those that came out in 1894 were called Brood II, and so on, according to Kritsky.

The 13-year cicadas that made their appearance in 1894 were called Brood XVIII and so on. The cicadas that emerged in 2021 were part of Brood X.

How Rare Is Rare?

Thomas Jefferson was president the last time two broods of cicadas emerged the same year. 1803 was also the year of the Louisiana Purchase from the French. And this pairing of Brood XIII and Brood XIX cicadas won’t happen again until 2245.

“So is it rare? Yes,” Kritsky told NBC.

They Can Be A Nuisance

Cicadas’ mating calls can be deafening. They herald their arrival above ground with a high-pitched cacophony of buzzing that can reach decibels of 100 or greater — about the same as a subway train, forklift, or motorcycle.

Their carcasses also litter the ground. The last time the Northern Illinois Brood emerged, in 2007, “they were out in such abundant numbers that Chicagoans were having to remove them with shovels, to clear sidewalks and roads,” Floyd Shockley, an entomologist and the collections manager for the Department of Entomology at the National Museum of Natural History, told NPR.

It’s An All-Male Choir

The mating song of the cicadas is performed by an all-male choir. Only males have sound-producing tymbal organs, sometimes called drummers, on either side of their abdomens just beneath their wings.

It’s easy to pick out the males — if you’re not too squeamish to pick them up and examine them.

A female has an oval-shaped reproductive structure with a hallow-point needle-like structure at the end called an ovipositor that she uses to cut a slit into a tree or shrub to deposit her eggs.

Cicadas Are Harmless

Cicadas don’t bite humans, and they don’t spread disease. They can harm young trees when the females lay their eggs in new tree growth, according to Cicada Safari, a portal created by Kritsky.

The best defense is to loosely wrap the branches of a young tree in cheesecloth to keep female cicadas from using the branches as a depository for the eggs. In more mature trees, egg-laying is a natural pruning that makes the trees more productive in flowers and fruit the following years.

Pesticides won’t kill cicadas and are not recommended. There are good reasons to allow them to live. For one thing, the underground tunnels created periodical cicadas naturally aerate the soil. They are also a food bonanza to all sorts of predators, and their decaying bodies contribute a massive amount of nitrogen and other nutrients to the soil.

Cicada Tourism Is Big

Kritsky released an app in 2019 called Cicada Safari that allows citizen scientists to report cicada sightings where they live. He told NBC he already has heard from a handful of people who want to plan their vacations around the cicada emergence.

“In the past, I’ve also had people plan vacations to leave while the cicadas are here,” he told the network.