Billions of cicadas that have been burrowing underground for 13 and 17 years are now emerging in parts of the Midwest and southern United States.
“The southern states and central United States will be hit hardest,” says Paula Shrewsbury, an entomologist at the University of Maryland. “They will have billions of cicadas.”
Thirteen-year-old cicadas, Brood XIX, are found in Georgia, Tennessee, the Carolinas, and elsewhere in the Southeast. Brood XIII, the 17-year-old cicadas, emerged primarily in Illinois. Periodical cicadas, which stay underground for years and then emerge together, are found only in the United States.
“It’s one of the great mysteries of why these cicadas have evolved very long life cycles, among the longest of any insect,” says Floyd Shockley, an entomologist at the Smithsonian’s National Museum of Natural History. , adding that it could be a reaction to radical changes. the temperature changed a long time ago.
“The last ice ages, which would have occurred after the evolution of Magicicada, may have forced them to have longer life cycles in order to survive periods when their host trees would have been affected by glaciers,” says- he.
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Cicadas spend their years underground as nymphs feeding on tree sap until it is time to rise, which occurs when soil temperatures reach around 17 degrees Celsius (64 degrees Fahrenheit) .
“That first night, their only goal is to turn into adults,” Shockley says. “It takes them several hours to complete this process. They usually start at dusk and do so primarily at night to avoid predators. It’s not a very effective strategy, but when you’re going out in the millions or hundreds of millions, you don’t really have to worry about surviving… there’s still plenty (of cicadas) for the breeding phase.
After a few days, the mating dance begins. Male cicadas gather in trees and begin singing to attract females, who will signal if they are interested.
“She will flap her wings and he will mate her. And once she’s mated, he inserts what’s called a copulatory plug, which plugs the female so other males can’t mate with her,” Shrewsbury explains. “But then he can move on and find other females to mate with.”
Mating can last from a few hours to a day. Once mated, females begin creating slits in the stems of tree branches where they will lay 400 to 600 eggs before dying.
All cicadas will only live above ground for four to six weeks, just long enough to mate and lay their eggs before the adults die off en masse. Eggs left behind hatch approximately six to eight weeks later. The hatched nymphs fall to the ground and burrow underground to start the cycle again.
Although cicadas may be a nuisance to some, scientists say they have ecological benefits and do not harm people or animals. For example, the millions of shed skins decompose and this organic matter is recycled back into the soil.
“And when they come out of the ground, they dig these holes, and those holes will add aeration holes for the roots of the plants. And water infiltration will be better, which will help plants grow better,” says Shrewsbury.
Insects also provide a nutritious food source for animals.
“We see a lot of feeding, particularly by birds, but also by mammals and reptiles that take advantage of the abundant food source,” Shockley says. “Wherever cicadas emerge, there is population growth of these predators. And so, they will have a very good season. And then, of course, their populations will naturally decline when this abundant food source disappears.
Cicadas can also be a source of food for humans. There are recipes for everything from sautéed cicadas to cicada tacos and chocolate-dipped cicadas. Shrewsbury and Shockley sampled them.
“Cicadas have kind of a nutty taste, but they are very nutritious,” she says. “Insects in general are very nutritious. »
“Most people prefer to go ahead and remove the wings and legs,” says Shockley. “Just because, I don’t know why, they think maybe it’s a little less scary.” But they are delicious.
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