Everything Everywhere Daily: History, Science, Geography & More - The 17-Year Cicada

Episode Date: May 25, 2021

Every 17 years one of the grandest spectacles in nature takes place. Billions of insects in a seemingly coordinated fashion will emerge from the ground and cover the skies and the trees. This is all part of their extremely unusual life cycle which consists of an extremely long juvenile period and very short adulthood. Learn more about periodic cicadas and their unusual behavior and life cycle on this episode of Everything Everywhere Daily. Learn more about your ad choices. Visit megaphone.fm/adchoices

Every 17 years, one of the grandest spectacles in nature takes place. Billions of insects in a seemingly coordinated fashion will emerge from the ground and cover the skies and trees. This is all part of their extremely unusual life cycle, which consists of an extremely long juvenile period and very short adulthood. Learn more about periodic cicadas and their unusual behavior and life cycle on this episode of Everything Everywhere Daily. What if your perceptions about the past were wrong? throughline is a podcast that takes you back in time to uncover the parts of the story that may have gone unnoticed. It effectively turned day into night and how it shaped the world now. Time travel with us every week on the Thurline podcast from NPR.

This episode is sponsored by audible.com. My audiobook recommendation today is Empire of Ants, the hidden world and extraordinary lives of Earth's tiniest conquerors. by Suzanne Fotzick. Ants number in the tens of quadrillions, and they have been here since the Jurassic era. Inside an ant hill, you'll find high drama worthy of any royal court, and between colonies, high-stakes geopolitical intrigue is afoot. Just like us, ants grow crops, raise livestock, tend to their young and infirm, and make vaccines. And just like us, ants have a dark side. They wage war, despoil environments, and enslave rivals, but also rebel against their oppressors. Empire of ants will inspire new respect for ants as a global superpower and raise

questions about the very meaning of civilization. You can get a free one-month trial to Audible and two free audiobooks by going to audibletrial.com slash everything everywhere or by clicking on the link in the show notes. Cicadas are a very common species of insect. There are over 3,000 species of cicadas all around the world and they can be found on every continent except Antarctica. Most of the species are annual species with a regular life cycle that occurs every year, with some species going dormant for several years. However, there is a particular genus in the cicada family called the Magi Cicada or periodic cicadas. They're found exclusively in the eastern part of the United States, and they have a very unusual development cycle. They will only appear once every 13 or

17 years. When they do, if you happen to be in the area, it can be an incredible experience. billions of insects will rise up almost simultaneously and create an incredible cacophony. So what exactly is happening, and why do they do this? Periodic cicadas engage in a reproductive strategy known as predator cessation. The idea behind it is pretty simple. It's basically taking a shotgun approach to reproduction. When the cicadas emerge, a whole lot of them are going to get eaten by predators like birds. However, if you have multiple billions of cicadas, they can't eat all of them.

It's sort of like the online campaign a few years ago to get a million people to rush into Area 51. If you get enough people, it would be impossible to stop them all. A one-acre plot of land with periodic cicadas can have as many as 1.5 million of them emerge at the same time. Sometime in the spring of the year that they're going to emerge, they begin digging tunnels to the surface. Some might actually build small mounds, which occasionally. extend above the surface. They are all waiting for the ground temperature to reach a certain level, which is about 64 degrees Fahrenheit or 18 degrees Celsius. When the temperature reaches that point, which is usually in late April or early May, depending on the area, they all come out at exactly

the same time. All of the cicadas which emerge at the same time and the same schedule are considered to be part of a single brood. There are 23 of the broods in the United States, which are on separate 13 or 17-year timers. In 2020, 21, the largest brood, Brood 10, is coming out, which is why people are making such a big deal out of it. Brood 10 is actually scattered over multiple states, from Ohio to Tennessee to Indiana, Pennsylvania, and a few others. So, what do the cicadas do once they leave the ground? Once they're out, they are considered nymphs. They are still in the casings which they've been growing in in the ground, and the first order of business is to molt.

They will do that either on the ground or on some vertical surface. They will then do nothing for a few days as they wait for their exoskeletons to harden and finalize their transition to adults. I should note that cicadas are not locusts. Locas are more like grasshoppers. They have a mouth and they eat things. Cicadas don't have a mouth. They have more of a sucker like a mosquito.

They feed by making small slits and plants and consuming their fluid. They might damage the plant, but they really don't consume them per se and they won't kill them. They won't wipe out an entire field of crops. As an adult, a cicada has one real purpose in life, to reproduce. At this point, once it becomes an adult, it only has a few more weeks to live. And during this time, it has to not be eaten and try to find a mate. The males will make an incredibly loud sound that can reach up to 100 decibels, which can be as loud as a motorcycle or a jackhammer.

The females will then be drawn to one of the males, and they'll make a V-shaped cut in a twig where they will lay their eggs. They might leave about 20 to 30 of these cuts in a tree and lay a total of about 600 eggs. In 6 to 10 weeks the eggs will hatch, and the nymphs will fall to the ground where they will burrow into the soil and wait for 13 to 17 years before they come out again. By the time the nymphs fall to the ground, all of the adults who have laid the legs will be dead, and they will be fertilizer for all the plants that they've been feeding off of for the last decade. How do they live when they're underground? Well, they feed off the liquids and the roots of plants.

They just cut slits in it as they do in their adult stage. One question many people have is, why do they come out on 13 or 17-year cycles? It's a really long time, and the vast majority of other cicada species have cycles that are nowhere near this long. Well, the best guess most researchers have is that 13 and 17 are prime numbers. That means that other species, which might feed on the cicadas, can't develop a reproduction cycle of their own that could be used to feed on them, unless they too followed the exact same 13 or 17-year cycle. And because it's such a long cycle, it's really hard to do.

One of the surprising animals which eat cicadas are humans. Cicadas have a very similar nutritional profile to shrimp. Many people call them land shrimp. People with shellfish allergies often have allergies to cicadas. The key is to get them right after they come out of the ground before they develop their hard exoskeleton. You only have a short window of about a week to harvest them. Most people will put them in the freezer to kill them and then boil them to clean off anything which might be on them.

And from there, you can fry them, bake them, or whatever. Cicada tacos have become very popular. So, if you happen to be in an area where the periodic cicadas are hatching, put in some earplugs to drown out the sound and enjoy some cicada tacos, because you aren't going to get another chance until the year 2038. The associate producer of Everything Everywhere Daily is Thor Thompson. If you'd like to support the show, please donate over at patreon.com. There is content only available to supporters, merchandise, and even opportunities for a show producer credit.

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