Brace yourself, the cicadas are coming.
The all-encompassing, eardrum-numbing buzzing that accompanies their summer arrival will be extra loud this year as two cicada broods emerge around the same time. Periodical cicadas are considered some of the loudest insects in the world, and their mating calls can be as loud as a lawn mower or motorcycle, according to the National Institutes of Health.
For the first time in more than 200 years, Brood XIX, known as the Great Southern Brood, and Brood XIII, known as the Northern Illinois Brood, will emerge from the ground nearly simultaneously, though largely not in the same locations.
A brood is a large group of periodical cicadas that emerge during the same year, says Hannah Burrack, professor and chair of the Department of Entomology at Michigan State University. Brood XIX emerges every 13 years and Brood XIII emerges every 17 years. The difference between periodical and annual cicadas is the amount of time they spend underground. Annual cicada nymphs stay underground for two to five years, though the species emerges every year, while periodical cicada nymphs stay underground for either 13 or 17 years.
“Brood XIII and Brood XIX only synchronize every 221 years,” says Floyd Shockley, an entomologist and collections manager at the Smithsonian National Museum of Natural History. “So, the last time they emerged together was in 1803 and the next time these two broods will synchronize is in 2245.”
Where Are the Cicadas and When Will They Emerge?
Much of the Midwest and Southeast will experience the cicada invasion this spring, but the cicadas won’t all emerge at the same time. Since cicadas wait for soil temperatures to rise above 64 degrees to emerge and molt, the southernmost brood will start emerging before their northernmost counterpart, says Shockley. Some Brood XIX cicadas have already been spotted in Alabama.
The northern brood will emerge in Iowa, Illinois, Indiana and Wisconsin, and the southern brood will emerge in Alabama, Arkansas, Georgia, Indiana, Illinois, Kentucky, Louisiana, Maryland, Missouri, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee and Virginia. It’s possible people in Illinois will experience both broods at the same time, Burrack says.
How Many Cicadas Will There Be?
While predictions for the number of cicadas have ranged from billions to trillions, Shockley says it’s “impossible to count them all with any precision or accuracy.”
“[If] there was only a billion and you were using a clicker, it would take more than 31 years of constant clicking to count 1 billion cicadas,” he says. “A trillion [cicadas or seconds] would take more than 31,000 years to count.”
Instead, experts wait until the cicadas have emerged and count the number of emergence holes in the ground in a square foot, then “extrapolate out to larger and larger areas until we cover most of the distribution range of a brood,” Shockley says.
“The other confounding issue is that all of the cicadas in a given place are not coming out at the same time on the same night. It’s staggered,” he says. “Some cicadas are better at telling soil temperature than others, so it lasts a couple of weeks. So, we don’t often have the opportunity to refine our estimates until the entire emergence is over.”
How Long Are Cicadas Above Ground?
The cicadas, which will be above ground in any one place for four to six weeks, are almost exclusively looking for mates. The males will be singing in large clusters, and the females will fly around looking for the “best singing males to mate with.”
“They feed a little bit to keep themselves alive, but adulthood is all about mating,” Shockley says. “Their time above ground is for mating and laying eggs and once they have done that, they die.”
After about two months, the eggs laid by the females hatch, the nymphs drop from the trees to the ground and go into the soil, and the cycle begins again.
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Are Cicadas Safe to Eat?
Cicadas are perfectly safe for pets – and humans – to eat as long as they haven’t been sprayed with pesticides or have a fungal infection. Shockley says they have a “nice earthy, nutty flavor when cooked.”
“They are actually quite versatile…depending on which life stage you are using. Nymphs are very similar structurally and texturally to shrimp, teneral adults are very soft like soft-shell crab, and full adults are crunchy and full bodied,” Shockley says.
However, people with seafood or shellfish allergies should skip the cicada snack since their exoskeleton is made of the same component as crustacean shells.
Do Cicadas Have an Impact on the Ecosystem?
Cicadas’ emergence holes create conduits for oxygen, water and nutrients to penetrate deeper into the ground. In addition, the “natural pruning event” that occurs when females lay their eggs in tree branches encourages more tree growth the following year.
“The tree species they feed on as nymphs and oviposit into as adults have evolved with the cicadas so they are tolerant to this activity,” Shockley said. “And the beauty of the periodical cicada life cycle is once they mate, they all die relatively close to where they emerged. Meaning, they return the nutrients that they received from the trees as their bodies decompose.”
