As Illinois awaits a massive, rare double-brood emergence of cicadas, entomological research shows that the insects may come earlier.This year, two 'periodical' cicada species—Brood XIII and Brood XIX— will emerge simultaneously. Maps of Illinois show where each brood is expected to flourish. According to Jennifer Rydzewski of the Forest Preserve District of DuPage County, brood XIII occurs in the Chicago area only every 17 years, while Brood XIX occurs every 13 years.
Climate-related disruption of the cues periodical cicadas use to pick their year of emergence will lead to an increase in unexpected, oddly-timed emergences or even the breakdown of these insects' periodicity. The study mentions notable off-cycle emergences have already occurred, such as the unexpected emergence of Brood X cicadas in 2017.'It's possible we are a few days ahead of schedule this year due to the warming climate, but we definitely need more data and analysis,' Dr.