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2024 is a special year for cicada season: for the first time in over 200 years, a “double brood” emergence of two extremely large cicada populations, Brood XIII and Brood XIX, will simultaneously rise out of the ground this spring, flooding the Chicagoland area with their signature chorusing. 

Brood XIII will arrive in northern Illinois, while Brood XIX will reach farther into southern Illinois and beyond, with an overlap expected around the north-central area of the state. Expect to start seeing (and definitely hearing) these 1.5-inch long critters as early as late April when the ground begins to warm.

This fascinating natural phenomenon is unique to Chicago, as these two particular broods are the only ones in North America to have a significant presence in Illinois. But seeing as Chicago wasn’t even a city the last time these broods emerged together, it raises questions as to what social or environmental impact — if any — these cicadas will have on the whole of the Chicagoland area. 

Read on to learn more about the effects of cicadas on our natural environment, and how to prepare for the ensuing Cicada Apocalypse of 2024!

The “Cicada Apocalypse”

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The last time Brood XIII and Brood XIX emerged at the same time was in 1803, the year of the Louisiana Purchase. The broods are known as “periodic cicadas”, and emerge from the ground in 13-year and 17-year cycles. It is anticipated that around 1.5 million cicadas per acre will emerge in and around the Chicagoland area.

While the cicada populations will be noticeably larger than they have been in the last decade, most people will not fully experience the rare double emergence, as the overlap will only occur in a small section of north-central Illinois.

The cicadas will emerge once — around late April or early May — and remain above ground for about 4-6 weeks.

Anyone who has experienced cicadas before will be met with similar experiences this spring, just to a more noticeable degree.

• Their chorusing, which are their mating calls, will be much louder. 

• More cicada exoskeletons will be noticed on trees.

• Dead cicadas will cover the ground by larger quantities, and contribute to a more pungent odor as they decay.

But they will follow the pattern they always have during their cycles, which is to emerge from the ground, cling to trees for nutrients as they mature, mate, lay eggs on twigs and branches, and the next generation will return to the ground for the next 13-17 years.

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The more noteworthy aspect of the double brood emergence is a scientific one: whether or not the cicadas from Brood XIII and Brood XIX will interbreed. Cicadas from the two broods are classified as different species, so scientists and researchers are curious how the next several generations of hybrids will develop as a result. In the short term, it is likely that the offspring will choose one or the other broods and join the 13-year or 17-year cycles.

The Environmental Implications

With billions of cicadas comes a short period of environmental change. Insects of this volume will naturally and noticeably impact plants and wildlife, as well as be influenced by the rapidly changing climate of today. 

Will cicadas of this volume harm the environment?

Luckily, cicadas are not at all dangerous to humans (if you don’t count the constant and annoying noises they make in the dead of night). They are not venomous, do not bite, and will leave you alone unless you look eerily like a tree. They pose no risks to pets or gardens.

They can, however, pose a risk to trees and shrubs. because the wood on twigs is soft enough that the female cicada can carve small, protective burrows to place the eggs in. Many branch tips will wither and die, stunting the tree’s overall growth. The biggest threat is to saplings and newly planted orchards.

However, cicadas can be equally beneficial in providing nutrients to the very same trees. After the mating cycle is complete, the adult cicadas die and fall to the ground, leaving their bodies to decompose into nitrogen — an important nutrient for growing and budding trees.

When the next generation of cicadas hatch and burrow back into the ground, the little holes they dig aerate the ground and provide optimal conditions for water filtration. While the baby insects go on to munch on tree and shrub roots for their own nutrients, this hasn’t been known to be a serious issue, especially to plants that are already matured.

Cicadas, which, tend to provide predators with a surplus of food and nutrients during the 4-6 weeks they’re above ground. Periodic cicadas have such large populations that predators can have their fill of the insects and not make a dent in the overall population. With the incoming double brood emergence, this will only hold more true.

How will climate change impact cicada populations?

While these cicadas have evolved to withstand predators and other threats to their species by sheer volume, it is believed that like all living creatures, the cicadas’ behavior will start to change as the climate does. 

Global warming, for example, may implicate that cicadas will begin emerging from the ground earlier and earlier into the year, if the weather allows for the hastened warming of ground temperatures. If this happens, it may have further implications on the actual length of the cicadas’ cycles, and if they’ll begin to emerge more often or more irregularly. 

If climate change afflicts the habitats of the insects’ existing predators, and predator populations begin to dwindle, the cicada brood sizes may continue to rise to levels we’ve never seen before. The overcorrection of cicada populations may result in them overfeeding on the trees they normally flock to for nutrients and breeding grounds.

How to Prepare

The nice thing about cicadas is that if they’re left alone, they don’t cause much of a disturbance. They are very much a part of North America’s natural environment and will come and go without too much strife…mostly. But if you’re worried about the presence, smells, and especially the noises of these cicadas, here are some tips to prepare you for the impending cicada apocalypse:

1. Don’t try to harm them.

Pesticides are . They are harmless in their own right, so the best case scenario of using pesticides against them is that another animal will come along, eat them, and get sick.

The cicada larvae that move underground will, however, be harmed by pesticides and chemicals sprayed onto lawns. And since they are not in hibernation, but constantly burrowing underground for up to 17 years, killing them prematurely may diminish the benefits of aeration and water filtration. 

2. Protect your growing trees and plants.

If you’re worried about the cicadas damaging your trees or other plants, you can protect them with thin, unobstructed materials like cheese cloth or mesh netting placed over the plant. This will allow beneficial insects to still have access to the plant while preventing the “predatory” insects from pursuing it further.

3. Dispose of dead cicadas responsibly.

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You have the option to let dead cicadas decompose back into the ground, but if the smell and sheer volume is getting particularly bad in your area, there’s no harm in disposing of them responsibly.

Try to clean up as fast as possible to avoid lingering smells, using shovels or rakes for your yard and smaller trowels if they start making their way into your gutters. You can dispose of them along with the rest of your trash or in an outdoor compost pile.

4. Invest in some really good earplugs or noise canceling headphones.

Cicadas on a normal year can be surprisingly loud, reaching decibel ranges similar to that of a lawnmower. They can get to noise levels of 90 decibels or higher, . So if you don’t have some already, consider investing in a good pair of earplugs or headphones to protect your ears (and your sanity) this spring. 

5. Most importantly…be on the lookout!

The next time a double emergence between Brood XIII and Brood XIX will happen is in the year 2245…and even the broods by themselves won’t be seen until you’re well over a decade older. So be on the lookout for these fascinating insects while taking a stroll through Grant Park, or take a day trip to Springfield where the suspected overlap of the broods may fall.

Historic events like these are once-in-a-lifetime opportunities. And this one is exclusively happening for Chicagoans!

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