by Mark Harvey
“…they came out of little holes in the ground, and did eat up the green things, and made such a constant yelling noise as made the woods ring of them, and ready to deafen the hearers…” —William Bradford, Massachusetts, 1633
If you missed the totality last month when the moon fully obscured the sun and can’t wait until August 23, 2044, for the next total solar eclipse, don’t despair. There are still some very good reasons to rent a strange Airbnb in a strange county you’ve never visited to witness another rare event in nature: the emergence of a trillion cicadas. If you’re inclined to get the best seats for this event, you might want to start looking at flights to Illinois and Iowa, where the bugs will really take over.
For those who don’t follow cicadas, this year we’re seeing what amounts to a Sturgis rally or Woodstock for insects: a hell of a lot of showing off, really loud music, lots of sex, and truly living for the moment. Periodical cicadas, as they’re called, live underground as nymphs for years, and then spend only a few weeks above ground as adults after they’ve emerged to mate. There are two types of periodical cicadas, one which emerges every thirteen years, and one which emerges every seventeen years. What’s exciting this year—if you’re an entomologist—is that two adjacent broods, one from the seventeen-year gang and one from the thirteeners, have synched up so they are both emerging the same year. The last time this happened was in 1803.
This being America, there’s even a clumsy portmanteau to describe making a special trip to hear the insects: cicada-cation.
There aren’t too many places that the two broods will overlap but Dewitt County, Illinois appears to be one of them. And of course, Reddit has a thread that can help the insect lovers find the best viewing places. In fact, one thread is titled “Double Brood Emergence—best viewing locations?” It’s not a long thread but the enthusiasm is genuine. One Redditor writes, “My mom has ‘listen to cicadas’ on her bucket list so we’re planning a trip from the PNW. Now that we’re a bit closer, any tips on timing and places to stay?”
I live in a part of the world where there aren’t any periodical cicadas so I’m a little envious of those who get to witness this event. It’s going to be really loud. Audiologists tell us that when the male cicadas are trying to attract a mate, they can be as noisy as 100 decibels. That’s 10 decibels louder than a lawn mower. The males make the sound by flexing their abdomen at a high frequency and their hollow bodies create a resonance. The cicadas synch their mating calls in roughly one-second periodicity at frequencies between 2.5 kilohertz and six kilohertz. Us humans don’t even get into the kilo-hertz range and speak in voices ranging from about 90 to 250 hertz. Sad!
The female cicadas are a little more demure and only make a quiet click with their wings when they see a male they like. I’ve read that female humans have ways of communicating their attraction with subtle gestures such as flipping their hair, laughing at your jokes, and making eye contact. While us human males sometimes miss those cues, not so the male cicadas. If you haven’t watched the video of Sir David Attenborough successfully imitating a female cicada and attracting a sex-starved male cicada, you really haven ‘t lived have you? Attenborough just repeatedly snaps his fingers, approximating the sound the females make with their wings. The video does show how indiscriminate and licentious male cicadas are after thirteen or seventeen celibate years underground. With his oxford shirt and plummy accent, Attenborough has little resemblance to a cicada and yet the male on his video goes at him like a shameless barfly.
Scientists tell us that cicadas have very few natural defenses so their mode of survival is to hope predators choose one of the other trillion cousins on the same mating cycle. The scientific term for this is predator satiation. Studies have shown that birds, one of the main predators for cicadas, just plain can’t eat all of the billions of cicadas even when they gorge themselves.
It’s a bit like a vast police lineup where you just hope the hungry bird or racoon chooses the other guy, not you. The years when vast numbers of cicadas emerge take the pressure off other insects such as caterpillars. And the trophic effect of caterpillar booms—sometimes double the numbers–is very hard on trees. So while the cicadas themselves don’t do much damage to the trees, the sometimes doubling in caterpillar numbers does.
The sharp reader will also notice that the cycle of cicada emergence and mating is based on two prime numbers: thirteen and seventeen. This makes it much harder for predators that have, say, a life-cycle of two, four, or six years to mesh with our loud prime-numbered friends. As an example, if a predator had a life cycle of four years, it would only sync with a 13-year cicada every 52 years (22 x 13). So the feasting on cicadas would only happen every 13th generation of that predator. But if the cicada had a life cycle of twelve years, just one year shorter, it would sync up with the same predator every twelve years (22 x 3) or every third generation. And, no, they’re probably not that good at basic math and evolution probably doesn’t work that way.
But the precision of a cicada’s cycle is still otherworldly: how do they know 17 years have passed? In a word, no one knows. Even if you read Entomology Today, you will get a pretty unsatisfactory answer as in “they must have an internal molecular clock.” Some entomologists surmise that their timing is based on their consumption of a tree’s xylem (sap to us laymen) and the changes of its composition throughout a year. This supposition is based on an event in 2007. When a warm January in Ohio followed by a hard freeze in February and then a normal spring produced two leaf sets on maple trees, several hundred 17-year-cycle cicadas emerged on what was just the 16th year.
The other element that seems very precise in the life of a cicada is that they don’t come out of the dirt until the ground reaches 64 degrees Fahrenheit. I once had a baseball coach that used to tell us over and over that being on time means showing up 10 minutes early. If you’re a cicada, that’s very bad advice. Coming up out of the ground early means you’re probably going to get eaten immediately by a bird or a racoon that hasn’t yet sated himself on your billions of cousins who aren’t trying to impress the world with their punctuality.
One of the things I always miss about America when I’m traveling abroad is the unabashed willingness to go full-on-tacky with our language, sculpture, painting and advertising when necessary. You won’t see enormous fake dinosaurs to lure families at gas stations in Switzerland, but in Utah or Colorado you can fill your tank in a majestically fake Mesozoic atmosphere with Tyrannosaurus-o-plenty. So it is with cicadas and our singular ability to commercialize every natural event. There is cicada themed beer, cicada-shaped chocolate-covered strawberries, and t-shirts emblazoned with the bug and a motto that says “2024, The Comeback tour.”
Another t-shirt says “Brood XIII, Song of our People, US Invasion Tour of 2024.” There are mugs that say, “2038, Save the Date, Brood X will be Back.” And of course there is the branding: cicada-palooza, cicadageddon, and cicadaclypse. Some countries have universal health insurance, but no one can do merchandise or branding like us. Not even close. USA!
Cicadas have a strong place in mythology through various cultures. One of the most charming myths takes place in ancient Greece during an important musical competition. One of the contestants, a man named Eunomos, breaks a string on his instrument just when he hits the last high note of the song. Magically a cicada appears and sings the missing note perfectly to help Eunomos win the competition.
Thousands of years ago, the Chinese regarded the cicadas way of emerging from their exoskeleton as a symbol of rebirth. Thus began a tradition of placing jade carvings of cicadas in the mouths of their dead to encourage reincarnation. In the Hopi mythology, cicadas emerged out of the Grand Canyon to lead their people into the fourth world. Hopi also placed stone cicada carvings in the mouths of their dead.
So what are you waiting for? There are flights to Champaign, Bloomington, and Decatur airports in Illinois, all within easy driving distance of where the action and arthropods are. The AirBnb’s around there are very reasonable—some as low as $45/night if you don’t mind rooms a little heavy on tchotchkes, bibelots, and bagatelles. The next time these particular two broods of cicadas will sync up again will be 221 years from now. I guarantee you flights will be more expensive.