COLUMBUS, Ohio — When Brood X cicadas make their appearance later this month, it will mark the third time David Shetlar has witnessed and documented their emergence, which occurs every 17 years.
In the days leading up to when the loud, large-winged insects surface from underground, where they have lived on tree roots for nearly two decades, Shetlar, who calls himself “Bug Doc Dave,” has been monitoring their progress.
When the cicadas pop out, they will have a wingspan of about three inches. In a strategy designed to overwhelm their predators, they will emerge in large numbers.
Nationally, experts say their numbers could easily reach the trillions. Ohio is one of 16 states where they will crop up.
Carrying a garden trowel and a kitchen meat thermometer, Shetlar, an entomologist who taught at universities including Ohio State University, where he remains a professor emeritus, walked off the trails at Prairie Oaks Metro Park in West Jefferson, Ohio, last Thursday morning.
Moving into a wooded area, Shetlar pushed away honeysuckle branches that have become lush with leaves and clusters of white blooms since his last visit weeks earlier.
The ground was still muddy from an inch of rain earlier in the week.
It didn’t take long for Shetlar to find the turrets of dirt with holes in them — the cicadas’ “chimneys,” built to help keep water and mud out of the insects’ holes.
In some cases, the cicadas had built their chimneys into exposed tree roots. In one section, there were nearly a dozen chimneys in one square foot.
“I can’t believe how deep these things are,” Shetlar said as he plunged the trowel into the mud.
“You little rascals,” he scolded the cicadas, which were more than a few inches below the surface.
The cold weather led the insects to retreat six to seven inches into the ground. Shetlar jabbed the thermometer deep into the soil. The temperature hovered around 49 degrees.
Cicadas won’t burrow through the mud and surface until the soil reaches 64 degrees about eight inches below the surface. While air temps can rapidly change, soil temperatures take longer to adjust.
With recent cool weather and forecasts not hitting highs of mid-60s until later next week, the cicadas aren’t ready.
A few weeks earlier, the cicadas were near the surface and completely light brown, Shetlar said. But when the cicadas are ready, they will form black spots on the back of their heads just behind their eyes.
“You’ll notice the wing pads are turning a creamy white color,” he said. “Basically what they’re doing is getting the beginning of the pigmentation they’ll have as adults.”
How long until the cicadas emerge in Ohio is anyone’s guess.
“It may be the third or fourth week of May until we start seeing them,” said Shetlar.