They were expected to make their first appearances last week, coming out of their mud mounds and climbing trees to find love. But this month’s cold temperatures have delayed the emergence of the 17-year periodical cicadas known as Brood X.
Entomologists in Ohio had expected the emergence to begin last week. On May 12, Joe Boggs did some digging in Butler County and found cicada nymphs that looked exactly the same as they did two weeks before. They still hadn’t acquired the darker colors and adult characteristics that mark their exit from the underground.
The soil temperature needs to reach 64 degrees consistently before the mass exodus takes place. With freeze warnings on so many mornings, “who knows when that will be?” he said.
That may be a bummer to cicada fans eagerly awaiting their reappearance for the first time since 2004. To others, the delay may be a welcome respite.
“There are people who are panicking, I don’t know why,” Boggs said in a Zoom program titled Periodical Cicada Brood X (10): Apocalyptic or Just Ho Hum?
No reason to worry
An assistant professor with The Ohio State University Department of Entomology and commercial horticulture educator with the OSU extension, Boggs wonders if the worry dates back to some of the first colonists.
“The Puritans came from England, where there are no periodical cicadas. They’re looking at this huge emergence and assumed it was what happened in Exodus,” he said, referring to the Biblical account of the plague of locusts that was sent to Egypt when Pharaoh refused to let the Israelites go.
The ravenous insects ate every crop, leaf and speck of green before a wind blew them into the Red Sea.
Boggs says it’s important to remember that cicadas are not locusts; they’re not even kissing cousins. Locusts are in a different insect order and are related to grasshoppers, while cicadas are family to stink bugs and aphids.
They have the same kind of mouthparts as a mosquito — made for piercing and sucking, not chewing — so they cannot consume vast quantities of greenery, as locusts and grasshoppers do. Piercing and sucking is what the Brood X cicada nymphs have been doing for the past 17 years.
They feed on xylem fluid from the roots of hardwood trees, mostly in the upper eight inches of the soil.
“So the trees probably had to be there, undisturbed, for multiple 17-year cycles,” Boggs said.
In other words, there won’t be any periodical cicadas emerging in housing developments built on former corn or soybean fields, while places like Cincinnati’s Spring Grove Cemetery & Arboretum, near where he lives in Hamilton County, “could probably be nicknamed Cicadaville,” he said.
Suit of armor
All insects have exoskeletons, as opposed to our endoskeletons, so when they want to get larger, they have to “molt the old suit of armor,” Boggs explained.
While butterflies undergo complete metamorphosis, changing from a crawly caterpillar to an elegant winged insect, cicada nymphs just keep growing bigger, molting the old armor as they go.
It’s in their last stage that they emerge from the ground and climb the trees whose roots have fed them all these years. At this point, they are actually fully-formed adults with wings but are still trapped in a teenager’s suit of armor.
At some point in their climb, the exoskeleton splits down the middle and sticks to the tree. The cicadas are then free to fly, but they usually don’t go far.
Males emerge first and begin singing to attract a mate. It’s when the males synchronize their singing and sound like one that things really get loud. Their choruses can reach 100 decibels, the same as a jackhammer or a gasoline-powered mower.
The females, meanwhile, can be carrying as many as 500 eggs in their abdomens. After mating, they climb further up in the trees and begin laying their eggs in branches that are usually a quarter- to a half-inch in diameter.
Using ovipositors that are hard as nails, the females lay 40 or 50 eggs at a time in straight lines, which causes damage to the branches. The damage is intentional; the females are hoping those branches will die and fall off. Why?
“The branch might be 75 feet in the air, but the goal is to get their offspring to the ground,” Boggs said.
The parents die not too long after mating, while the eggs remain in the branches for six to 10 weeks before hatching. In July, people might begin to see “flagging” on the trees as the leaves of those branches turn red or brown and the branches wilt or break off.
But this is not a bad thing said Boggs, who gives frequent updates about Brood X on OSU’s Buckeye Yard & Garden online at bygl.osu.edu.
“The damage is actually natural pruning,” he said. “Next year the tree will have a heavier canopy and will provide more food for birds and animals.”
Tens of thousands of cicada bodies rotting return nutrients to the trees, not to mention providing a smorgasbord for wildlife. And nymphs burrowing into the ground provide aeration and additional water for trees.
The bottom line is that owners of woodlots and forested land needn’t fear a 17-year cicada apocalypse.
“This is a native insect that’s been in Ohio tens of thousands of years,” Boggs said. “They haven’t managed to kill all the trees yet.”
Protect young trees
The greatest concern is damage to newly-planted or young trees. But homeowners must resist the urge to wrap them tightly in cloth or row covers, like a mummy. This stunts new growth and distorts branches, which is permanent.
Instead, Boggs recommends using half-inch mesh and gently draping it over the tree. He’s also heard from a woman in southwest Ohio who uses white tulle of the sort used for bridal veils.
Speaking of bridal, an Ohio couple admitted to a bit of cicada panic when they were interviewed recently on CBS This Morning Saturday.
Worried that cicadas would invade their outdoor wedding this summer, they contacted the man considered the expert on the subject, Dr. Gene Kritsky. Dean of the School of Behavioral and Natural Sciences and Professor of Biology at Mount St. Joseph University, Kritsky literally wrote the book on 17-year cicadas called Periodical Cicadas: The Brood X Edition.
He assured the couple that the cicadas would most likely be gone by their July 3 nuptials.
Check the app
In the segment, CBS environmental correspondent Ben Tracy also mentioned the Cicada Safari app that Kritsky created along with the Center for IT Engagement at Mount St. Joseph. More than 100,000 people had downloaded the app as of last week, but Kritsky and other entomologists are hoping many more will do the same.
The app allows folks to take photos of cicadas with their phones, then sends them to Kritsky and his students. They not only verify the cicada sighting, but map the latitude and longitude of the spot where the photo was taken. This citizen science will result in valuable data on exactly where periodical cicadas are emerging in Ohio and elsewhere.
In a Zoom program titled Periodical Cicadas: What Can We Learn From Them? Kritsky said Brood X cicada sightings were first documented at a Swedish Lutheran church in Philadelphia on May 9, 1715.
“Ben Franklin knew about them when came out in 1749,” he said.
The technology in the Cicada Safari app, and the articles Boggs writes for BYGL, not only add to the science behind Brood X, but also the historic record. Both men recommend getting out and enjoying the phenomenon rather than fearing it, and involving kids whenever possible.
“These are bugs of history,” Kritsky said. “Make some memories this year because you’re going to remember this in 2038. And who knows, it could also ignite a spark for natural history and science.”
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