For the first time since 1803, cicada broods XIX and XIII are co-emerging throughout the eastern and midwestern United States this summer.
Broods XIX and XIII are periodical cicada broods, meaning they emerge from the ground on a fixed schedule every set number of years. Brood XIX emerges every 13 years, and Brood XIII emerges every 17 years.
There could be around one or two million cicadas per acre spanning from Maryland to Oklahoma, which means trillions, if not quadrillions of insects will be present this summer, said John Cooley, associate professor of ecology andevolutionary biology at the University of Connecticut Hartford.
Cicada broods do not tend to overlap geographically when they emerge, but southern Illinois may witness a co-emergence of these broods. Brood XIII is emerging in northern Illinois.
“Down by Springfield, Ill., Brood XIII will have a little bit of overlap with brood XIX, and there’s a small area that may actually have double the number [of cicadas], but for us in theChicagoland area, this is just going to be our normal level of the 17-year periodical cicada emergence,”said Tom Tiddens, supervisor of plant health care at the Chicago Botanic Garden.
According to Louie Yang, professor of entomology and nematology at the University of California, Davis, periodical cicadas emerge based on soil temperatures, usually surfacing after consistent warm weather, typically at the end of May.
When emerging in large groups, cicadas’ noise can be noticeably loud.
“Because so many of them come out of the ground at the same time, and their courtship and mating is really loud, they have a really loud call,” said Yang. “So if you’re in a place that has a lot of cicadas during this period, it can be deafening. It can be rock concert loud.”
According to Tiddens, cicadas’ noise can reach 100 to 120 decibels, which is comparable to the sound of a jet plane or chainsaw.
“I think the important thing that people need to know is that they’re not harmful at all,” said Tiddens. “They are not going to hurt you in any way. You could eat them, and your dog could eat them, with no worries there.”
Due to the high numbers of periodical cicadas that will be present this summer, predatory animals like birds, squirrels and chipmunks are expected to increase in population compared to past summers.
The next cicada co-emergence is predicted to occur in the year 2245.
“It’s sort of like seeing a comet or an eclipse,” said Yang. “This particular event, the co-emergence of the 13 and 17-year broods is a once-in-a-lifetime thing. It’s every 221 years. It’s once in several lifetimes, really.”