Attention, Midwesterns and folks in the Northeast: It’s about to get loud.
Brood X (for Brood 10) cicadas are pushing their way out of the ground and singing their song from Illinois eastward, with a dipping down to Georgia. So when is Brood X coming? The first members of this illustrious insect group were noted around the Baltimore and Washington, D.C., areas in mid-May, and the rest of their friends and family are expected to emerge within days. How big is Brood X? In the trillions.
So, what is so special about this group of insects? After all, don’t cicadas emerge every year, pretty much all across the United States? Yes. But not all species follow the same pattern.
Brood X, also known as the Great Eastern Brood, is a group of periodical cicadas, and these types—which have a life cycle of many years—are unique to the eastern part of the country. The rest of the nation sees species that have much shorter life cycles.
There are about 170 species of cicadas in the U.S., with three of those having a 17-year lifecycle (including Brood X), and four having a 13-year cycle according to nationally renowned cicada expert Dr. Gene Kritsky, of Cincinnati’s Mount St. Joseph University. He literally wrote the book on this brood (The Periodical Cicadas: The Brood X Edition was published this year).
What Has Brood X Been Up to for the Last 17 Years?
The easy answer is: They have been living underground. This group grew from eggs planted in tree branches 17 years ago. “After mating, the females lay their eggs in the terminal ends of tree branches, about the thickness of a pencil,” says Kritskey. Each female carries about 500 eggs and lays them in clusters of about 10-30 or so in nests about a quarter-inch long. Once she runs out of branch, she flies to a new one if needed. About a day or so after laying her eggs, she dies.
“About six weeks after this, the eggs hatch, this year in late July or early August,” Kritsky says. The very young cicada lymphs wriggle free from their treetop nursery and drop straight to the ground immediately. They feed on grass and other shallow roots for weeks. For this group, “By New Year’s, they will be 8 to 12 inches underground, sucking on tree roots. Usually the one they nested in, “ Kritsky says. They don’t hibernate; they literally spend almost 17 years eating and tunneling down.
What Happens When Brood X Emerges?
After their 17-year feast, and once the soil temperature hits 64 degrees, the nymphs go topside and find a vertical surface where they can transform into an adult cicada. The insect pumps up its wings with fluid and fully transforms all within the first night it digs out of the ground. Then it’s back to the trees so they can mature a bit.
Why Do Cicadas Sing?
And that is when the males start their very loud singing, looking to attract their mate. Kritsky says he has measured a cicada’s song at 96 decibels, about the same as a motorcycle engine.
Are Cicadas Harmful to Humans?
The idea of trillions of insects emerging from the ground and flying all around your home and garden might sound a little nightmarish, but Kritsky says cicadas are actually not harmful to humans. “They don’t sting; they don’t bite; they don’t carry off small children,” he says.
Are Cicadas Harmful to Plants and Flowers?
And he also says the insects pose no danger to your garden. “They don’t feed on vegetables, flowers or annuals,” he says. “The damage they do cause occurs to very young trees, three to four feet in height that you just planted.” This is caused by the nesting females soon after they have climbed out of their tunnels and mated. If you live in the Brood X emergence zone and are thinking about planting some new trees, hold off a few weeks. If you have already planted a young sapling, shorter than five feet, you can buy a mesh garden bag to put over the whole tree and cinch at the bottom.
“The plant can still get air and water but the cicada can’t lay eggs,” Kritsky says. “You can probably start planting around June 20 and be safe.”
Can Cicadas Damage Your Land?
Although Brood X can be hard on your trees during nesting, they will soon fertilize the same land they grown on. When they die, they will accumulate around the base of your trees and may smell bad for a bit. You might be tempted to get the leaf blower and move that stench down the road, but hold off. Soon, the nutrients from the insects will go back to the tree and provide them fuel for growth.
Other Benefits of Brood X Cicadas
The cicadas’ life cycle has other benefits for nature. “The holes they make in the ground are like natural aerators. Their emergence is a food pulse for animals, birds and rodents, which provides more food for owls and raptors,” Kritsky says.
If Brood X is expected to emerge in your area—or if you are outside their zone but curious—you can check out the Cicada Safari app. This app, created by Kritsky, relies on residents to self-report when they see the Brood X clan in their area. You can upload a picture and help researchers and regular folks like the rest of us track their arrival. The eggs that result from this round of a Brood X “invasion” won’t show their multi-eyed faces until 2038.
Kritsky, Gene. Periodical Cicadas: The Brood X Edition. Ohio Biological Survey, 2021.