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2024 Cicada Invasion

Updated: Feb 28

It's the largest single emergence since 1803.

Vector drawing of a cicada superimposed over a birch tree in springtime in an open field with blue skies

Periodical Cicadas spend most of their lives underground and surface en masse every 13 or 17 years. In 2024, these remarkable bugs will emerge in central and southern U.S. in an event the likes of which hasn't happened in over 225 years.

Starting in late April and lasting through July 1st, two "broods" of cicadas numbering in the billions to trillions will start buzzing. Broods consist of multiple species of cicadas that merge on the same cycle. Brood XIX, or the Great Southern Brood has four species and will affect 15 states from Virginia down to Georgia and west to Oklahoma. Bood XIII, known as the Northern Illinois Brood has three species and will appear in Illinois, Wisconsin, Indiana, Ohio, and a bit of Michigan.

The Roman numerals assigned are based on a tradition established by the Department of Agriculture in 1893 when the first 17-year cicadas recorded emerged.

Mutual Assurance wasn't even a decade old the last time two "broods" emerged in the same year. Past Mutual Assurance member, Thomas Jefferson, was president, and that same year, 1803, marked the completion of the Louisiana Purchase. 2024's pairing of Brood XIII and Brood XIX, won't happen again until 2245.

Map of central and eastern U.S. with orange and green dots indicating where the 2024 cicada emergences will occur

What Makes Cicadas So Unique?

For bug enthusiasts, this year's emergence is a celebration of one of nature's marvels. Cicadas have the longest life cycle of any insect on the planet and have survived for 1.8 million years. Their singular purpose at emergence is to breed, and then they die in four to six weeks.

Unlike annual cicadas, which live between 2-8 years, periodical cicadas emerge in prime number years, which to some scientists helps explain their long existence. The fact that their existence is not divisible by any other number (except 1) means predators' life cycles are predicated on the existence of cicadas.

Entomologist Steven Jay Gould puts it this way:

"Consider a predator with a life cycle of five years: if cicadas emerged every 15 years, each bloom would be hit by the predator. By cycling at a large prime number, cicadas minimize the number of coincidences (every 5×17, or 85 years, in this case)."

So they spend their lives ticking away underground, waiting to emerge in mathematically elusive intervals so predators can't track them.

The Guys Make All The Noise

The mating song (buzz, cacophony, etc.) is produced by the guys. Their sound-producing tymbal organs, sometimes referred to as drummers, are rapidly vibrated by the insect's abdominal muscles. Each species of cicada (and there are over 3000 of them worldwide) has its own "song" pitch, frequency, and tone. You may notice that it will be quiet one afternoon, and then all of a sudden a swell of noise from the cicadas will start. Periodical cicadas synchronize their songs to form a chorus. Entomologist believe they do this to mark their territory and to alert each other to threats. In general, though, it seems the louder they buzz, the more the girls like it.

What This Invasion Means To Homeowners

Cicadas, whether periodical or annual, are relatively harmless. While underground, they live off the moisture in plant roots, and once they emerge, their only focus is on mating.

Cicadas don't bite, they don't spread disease, and the only possible damage they might cause is to young trees when the females lay their eggs on the new growth.

If you have young trees and want to protect them, you can loosely wrap their branches in cheesecloth to keep the females from depositing their eggs there. In more mature trees, egg-laying acts as a natural pruning tool that assists in producing more flowers and fruit in following years.

Pesticides don't work on cicadas and are discouraged. Cicada tunnels help aerate the soil, and they are a food bonanza for predators that happen to stumble upon their emergence. Cicada carcasses add massive amounts of nitrogen and other nutrients to the soil, so the adage, "live and let live" may have been created with cicadas in mind.

Of note - if you have a dog that likes to munch on whatever he can find, most dogs are OK if they eat a few cicadas, but if he gorges on the large, crunchy insects he'll find the exoskeleton difficult to digest and can suffer serious consequences. The American Kennel Club advises this:

"Preventing your dog from eating cicadas is the safest choice. Get ahead of the game and teach the “leave it” command. And if you have a pup who likes to eat bugs, you’ll need to be a constant companion when they go outside."

So while you may not be able to enjoy your quiet time on your porch or in the garden while the cicadas are in full chorus this Spring, enjoy this once-in-your-lifetime event for the rare natural phenomenon that it is.



Sources: Reuters, LiveScience, USA Today


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