116 3rd St SE
Cedar Rapids, Iowa 52401
National media outlets soon will be buzzing about the mass emergence of periodical cicadas in parts of the Midwest, Mid-Atlantic and Southeast in May. Eastern Iowans will be left to wonder what the Brood X brouhaha is all about because we won’t see it — or hear it.
It is a natural phenomenon, and the first time in 17 years that Brood X will be above ground to mate, lay eggs and die.
“This Eastern emergence is a big deal because it will happen near major media markets like Chicago, Washington, D.C., and New York. But it’s an emergence that most of us won’t see except through the media,” said Don Lewis, professor of entomology at Iowa State University.
The only cicadas bugging Eastern Iowans this year will be annual cicadas — the green or black cicadas that make noise during summer’s dog days from July to first frost, Lewis said.
Cicada is a large group of insects that are as big around as a thumb, about 1 inch or so long with sucking mouth parts. There are 3,000 cicada species. “They are most closely related to aphids and leafhoppers, and they have a simple life cycle — egg, nymph and adult. It may take three years to complete a life cycle.”
You’ll sometimes find a cicada exoskeleton clinging to a tree, a souvenir left behind as the nymph struggles into adulthood. The insects don't sting or bite and don't damage trees or foliage.
Periodical cicadas are different. Lewis described them as “unique and interesting” among insects in that they have either 13- or 17-year life cycles, most commonly 17. “From the time eggs are laid, through the nymph stage, the immature adults do not appear until 17 years later. It’s amazing because we’re used to mosquitoes that have a seven-day life cycle, 10 days for a house fly,” the entomologist explained. “There is an advantage for periodical cicadas having a mass emergence. If all of them emerge at once, predators can’t eat you out of existence.”
There are 15 regional broods, and broods emerge at different times. The last big brood in Iowa (Brood III) emerged in 2014 in a region that extends from Ledges State Park near Boone, down the Des Moines River valley all the way to Missouri. “Nationally, it didn’t get a lot of attention. That’s our biggest brood, and we’ll have to wait until 2031 to hear them again.”
Northeast Iowa had a periodical cicada emergence in 2007, slated to reappear in 2024. But surveys in 2007 also showed that “periodical cicadas are mostly gone from the state. Periodicals only live in permanently undisturbed wooded areas, forests, woodlands, river bottoms and flood plains, where trees are never disturbed,” Lewis said.
With bulging, bright red eyes, thick, 1 ½-inch-long black bodies and gossamer orange-veined wings, periodic cicadas are striking, but more than a pretty face. They’re also loud — really loud — because where the population exists, the number of insects emerging from the ground is huge — really huge.
“You’ll have 20,000 to 40,000 per tree which can sometimes be rounded to 1 million per acre in density. Midmorning, they’ll start singing and the sound is similar to annual cicadas, but there are so many of them that the sound becomes oppressive. It comes in waves and so loud that you can actually feel it press against your body.”
It’s the males singing in search of mates. “And it’s a cacophony. You hear it before you see it. When you come to the area in the sunshine from 10 a.m. to 2 p.m., you’ll see them fluttering from tree to tree, just filling the air. You stand in awe,” Lewis said. It's possible to see nymphs come out of the ground and cling, white and wingless, to tree bark and shrubs as they go through their final molt, shedding their exoskeleton. Wings expand and bodies dry and harden before the adult periodical cicadas fly up to the trees.
Lewis saw and heard Brood III’s emergence in 1980, 1997 and 2014 at Ledges State Park. “I’m counting on one more chance to be there for an emergence in 2031.”