After a 17-year wait, cicadas emerge a little early in Chicago area: 'It's a milestone'
This year marks a rare double emergence, with the cycles of the 17-year and 13-year cicadas aligning for the first time in 221 years. The last overlap of Brood XIX, four species that appear every 13 years in the Southeast, and Brood XIII, three species that appear every 17 years in northern Illinois, was in 1803.