Cicadas 2024 Illinois Map 2024. There are two groups of periodical cicadas โ those that emerge every 13 years and those that emerge every 17 years. After they emerge, the adults are white, soft, and squishy but will darken and harden overnight.
Gene kritsky at mount st. Adult periodical cicadas from brood xix are now completing its emergence as the brood is out in full force in states across the midwest and southeast, according to.