The emergence of an insect army may be delayed slightly in Kentucky. Here’s why
For the first time in 17 years, billions of cicadas from Brood XIV will take over broad swaths of Kentucky this spring and summer, and they’re already emerging in some parts of the state.
Central Kentucky is expected to be the epicenter of what one local insect scientist has named the “Bourbon Brood.” But has their arrival been somewhat delayed by the cooler, rainier weather Central Kentucky has gotten recently?
University of Kentucky entomologist Jonathan Larson says yes, but not by much.
“I think that it probably has delayed them slightly,” Larson told the Herald-Leader in a May 7 interview. Their arrival “should be imminent,” however, he added.
Technically, the cicadas are already here under our feet, waiting for the right signal to dig out from underground. Once that happens, they’ll take part in a weeks-long, insect music festival of sorts that will make Woodstock look like a tepid high school musical.
“I was out digging in my yard a couple of weeks ago, and I found them staged up in the upper layer of the soil,” Larson told the Herald-Leader.
So what needs to happen before billions of cicadas can takeover Kentucky? We asked Larson, someone who knows what to look for, about that. Here’s what to watch for.
What’s the trigger for cicadas to emerge from underground?
A periodical cicada spends most of its life underground maturing and waiting for the right time to emerge with millions of its buggy brethren. (In the case of Brood XIV, the second largest cicada brood, it’s billions, not millions.)
Prior to this spring, Brood XIV has spent 17 years feeding on sap in the root networks of trees. Its members “count” the passing years by tracking the ebb and flow of tree sap that cycles with the seasons. When the cycle runs its course 17 times, that’s the cue to start digging for the surface.
According to Larson, an easy way to anticipate cicada arrival in Kentucky is to look for the blooming of irises in the late spring. In the Bluegrass region, they typically reach their peak in mid-May. You’ve likely already noticed them around town or in your neighborhood, which means cicadas aren’t far behind.
In fact, they are already emerging in some parts of Kentucky, Larson reports. A homeowner in Bullitt County found some emerging on their deck, Larson said, adding he expects them to dig out in much greater numbers soon.
More precisely though, cicadas need soil temperatures to warm up enough before they feel ready to tunnel to the surface, where they’re exposed to the elements and are easy prey for predators.
Soil temperatures need to reach about 64 degrees Fahrenheit at about 8 inches deep, Larson said. That takes some consistently warm days.
When they do show up, male cicadas will take to the trees and start calling females in a loud song that can rival a jet engine. After pairing off to mate, the male cicadas die and the females find a good tree to lay their eggs in before dying, as well. Freshly-hatched cicada nymphs drop to the ground and start digging, and in the case of Brood XIV, we won’t see them again for 17 years.
How many cicadas can we expect in Central Kentucky this year?
A lot.
During a typical cicada emergence, about 1.5 million cicadas can occupy an acre of tree-covered land, according to Time, citing Cincinnati biologist Gene Kritsky.
Brood XIV is considered to be the second largest cicada brood behind Brood XIX, according to the University of Connecticut.
Central and Eastern Kentucky is expected to be its epicenter as the insect army rises across 13 states.
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