2017's Cicada Swarm Was No Fluke

Jan 5, 2018

The Cincinnati area now has a new sustaining brood of cicadas. In May 2017, insects associated with the Great Eastern Brood came out of the ground four years early.

Gene Kritsky of Mount St. Joseph University presented a paper in Denver in November confirming the new group.

"It occurred in such a broad area," he says. "The map of the sites occurs all the way from northern Indiana, as far south as Erlanger, and all the way into Fairfield and throughout greater Cincinnati. So we have the foothold of a well-established, reproducing brood of cicadas that wasn't here before."

Kritsky says the group is associated with Brood VI, which previously only appeared in North Carolina, South Carolina and Georgia.

A larger appearance of cicadas, Brood X, also called the Great Eastern Brood, will return to the Cincinnati area in 2021.

Kritsky is the dean of behavioral and natural sciences at Mount St. Joe and says the Brood VI insects came out early because of warmer temperatures.

"It's hard to think about that when you're sitting here in sub-zero temperatures," he says. "We're anxiously waiting to see what happens in 2021, and keep measuring this material and the emergences (to) get a better sense of how temperature might be fitting into this whole process."

Kritsky says two scientists, Monte Lloyd of the University of Chicago and Henry Dybas of the Field Museum, saw it coming.

"In 1966 they talked about how a 17-year cicada could come out four years early and then shift back to a 17-year cycle because that's what the mapping at the time suggested might be underway. They picked as the number one possible trigger to that would be environmental temperature increases."

Kritsky says Brood VI will appear again around Cincinnati in 2034, and will be about a fifth the size of Brood X.