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In a few months, they will make their way out of the ground, red eyes shining, a deafening song filling the air. It will be a company of creatures the likes of which have not been seen in the United States since Thomas Jefferson who was president – and it won’t happen again until 2245. Insects are so rare that some are referring to them as a cicadapocalypse.
Billions of cicadas are expected to emerge this spring and two different broods – one that appears every 13 years, and another every 17 years – will emerge at the same time. The 13-year group, known as Brood XIX, or the Great Southern Brood, is the largest periodic cicada brood, spanning across the southeastern United States. The Northern Illinois Bishop, or Brood XIII, rises every 17 years.
“It’s rare that we see this amount of double brood emerging,” said Dr. Jonathan Larson, adjunct entomologist and assistant professor at the University of Kentucky. “We’re talking about the absolute solitude of nature, one of America’s coolest insects.”
Although a chicadapocalypse seems looming, experts predict that the two broods will not overlap significantly, and that the bugs themselves, while loud and numerous, are harmless. Here’s what you need to know heading into cicada season.
What is known about cicada brood
These spring bugs are part of a genus, or group, of cicadas in the eastern US known as the Magicicada, or periodical cicadas. Three species emerge on a 17-year cycle, and four species on a 13-year cycle. (Scientists have long debated the significance of these numbers, which are the two main numbers – some researchers have suggested that the periodical cicadas are less likely to be killed by predators with a life span of 2 or 3 years , emerging in these prime numbered years, but the jury is still out.)
The following species periodic pattern is different from the “annual” cicadas, which do not actually have an annual life cycle, although you can see them every summer in much of the United States. Nymphs, or babies, of the annual cicadas spend two to five years underground, growing slowly, until they are ready to emerge. There are so many overlapping generations that there seems to be a steady stream of these cicadas every year.
Annual and periodic cicadas are easy to tell apart. Annuals tend to come out later in the year than periodicals. For example, annual “dog day” cicadas in the genus Neotibicen usually show up in the dog days of summer, around August, but the periodicals make their appearance in the spring. Although there are many species of annual cicadas, many of them are large and green. Periodic cicadas are smaller and mostly black, with bright red eyes and orange-tinged wings and legs.
Cicadas are divided into groups called broods based on when they emerge. Cicadas from multiple species can be contained in a brood. As long as they are adults in the same 13 or 17 year cycle at the same time, they are counted as members of the same brood.
When and where do the cicadas emerge?
These spring periodical cicadas will make their appearance when the soil temperature 8 inches deep reaches 64 degrees Fahrenheit (about 18 degrees Celsius). It will probably happen sometime in mid-May. The adult life span of individual bugs is only a few weeks, but their emergence will be staggered, so cicadas will be around six weeks.
That month-and-a-half period will be full of loud singing, mating and then dying, like “the most macabre Mardi Gras you’ve ever seen,” Larson said.
Parts of the Midwest and Southeast are in for cicadas this spring. Northern Illinois, along with southern Wisconsin, eastern Iowa and northwestern Indiana will likely see bugs from Brood XIII; in central and southern Illinois, most of Missouri and scattered areas of Kentucky, Tennessee, Virginia, Maryland, North Carolina, South Carolina, Georgia, Alabama, Mississippi, Louisiana and Arkansas are to find Brood XIX bugs.
There are several areas in central Illinois where the geographic ranges of the two broods were historically close and may have overlapped. However, predictions of a chicadapocalypse – where Brood XIII and Brood XIX appear in the same place at the same time – are probably exaggerated.
“We’re not even sure if they’re going to pass,” said Dr. Chris Simon, a professor of ecology and evolutionary biology at the University of Connecticut. Her research group at the university maintains a cicada information website, which includes maps showing where the hatchlings have historically emerged.
The double emergence of Broods XIX and XIII is rare, occurring every 221 years (when cicadas overlap 13 years and 17 years, as 13 times 17 is 221). These two broods have not been above ground at the same time since 1803, and after this year, they will not be brought together again until 2245.
However, the coincidence of different cicada hatchings, somewhere in the United States, is not so rare. It last happened in 2015; it will happen again in 2037.
Preparing for cicadas
Although there is unlikely to be much overlap between the two cicada broods, a large number of bugs does not mean only one brood is found in an area.
“You should expect lots and lots of cicada exoskeletons covering your trees and bushes. You should expect to hear a lot of noise,” Larson said. The insects are more likely to be in wooded areas near water, he said.
While the sheer number of insects, along with their distinctive jackhammer-loud sounds and bright red eyes, might give some people pause, Larson notes that cicadas are harmless. They are not a danger to garden plants. However, if you have young trees, cicadas may damage them when the insects cut into branches to lay their eggs. You can mitigate this damage by covering the trees with cicada nets.
Cicadas will not bite or bite you or your pets. If your dog eats a cicada or two, he said, the animal will be fine.
It’s not just dogs that are used to nosh on cicadas; people have been eating them for thousands of years. “They have a natural, sweet nutty flavor,” Larson said. (If you are allergic to shellfish, however, you should eat cicadas – a protein in shellfish that is linked to allergies is also present in many insects).
If you live in an area where cicadas are making an appearance this spring, you can download community science apps to help researchers studying these bugs.
“The main thing we want people to know is that they should download the Cicada Safari app, which is free on the web, and just take a photo of whatever cicadas they see, ” said Simon. Those photos are sent to scientists, who then map where and when the cicadas are emerging: information vital to scientists studying how climate change affects cicadas and predicting cicada activity In the future.
Beyond the larger scientific story of cicadas, Larson said he hopes people will embrace cicada spring simply because it’s a rare opportunity to witness some of the world’s most unusual bug behaviors.
“These are some of the coolest insects in America,” Larson said. “I hope people will appreciate this for what it is: this unique natural phenomenon that you don’t get anywhere else. It is lovely.”
Kate Golembiewski is a freelance science writer based in Chicago with special interests in zoology, thermodynamics and death.
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