Billions of insects will make a lot of noise this summer when they emerge from the ground after 17 years, but it will be a while before we see them in Wisconsin.
It may sound like something out of a science fiction movie, but it’s a normal part of the cicada life cycle. The big, noisy, flying insects spend nearly two decades in the ground, feeding on tree roots before popping up to mate and lay their eggs for several weeks at a time.
“We’re going to miss the fuss with this batch,” said University of Wisconsin entomologist PJ Liesch. “If the Wisconsinites really wanted to see these, you could drive a couple of hours and get into parts of Indiana or Illinois and see them, but we’re going to miss us here.”
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One of the largest groups, Brood X, will hit much of the eastern United States this summer, spanning 15 states from Georgia to eastern Illinois and Indiana. However, Wisconsin has its own group, Brood XIII, which has been out of service since 2007 and is putting them on track to get to the surface in 2024.
Liesch said that different cicada broods can look similar, but there can even be different species within the same brood. For example, Brood X has three different types of cicadas.
“You can really split some fine hair here,” he said. “One of the main ways they tell the broods apart is what year they come out and where they showed up in the US.”
Why do cicadas stay in the ground for so long? Experts say the bugs develop very slowly, which could serve a bigger purpose.
“It can very well be an evolutionary strategy to avoid robbery,” said Liesch. “If you are an insect or some type of creature that keeps popping up in large numbers, what feeds on you will cling to it. But if you come out on a long interval of 13 or 17 years for that Brood X group, then predators can’t understand that. “
Juvenile cicadas, or nymphs, spend most of their lives in the ground, usually only four to six inches deeper. They have stinging mouths like a mosquito that they use to suck fluids from tree roots (don’t worry, they won’t bite). The damage to trees is negligible and, according to Liesch, most people do not even notice that they are there.
However, they are hard to miss when they show up as they emit mating noises that can reach anywhere from 80 to 100 decibels, the equivalent of a low-flying airplane or lawnmower.
Once they mate, the females make small slits in trees and bushes to lay their eggs. When they hatch, tiny cicadas invade the ground, where the 17-year cycle starts all over again.
Larger trees are fine, according to Liesch, but immature plants and shrubs can be damaged. The millions of dead insects are also a great source of natural fertilizer, he said.
“If you get enough of the small cuts, this could provide an entry point for pathogens, or just the physical impact of all the cuts could cause some problems,” Liesch said. “On a large scale, they do a bit of plant damage, but they’re not out there damaging crops or anything like that.”
Contact Jake Prinsen at jprinsen@gannett.com. Follow him on Twitter at @PrinsenJake.
