The 17- and 13-year cicadas will both emerge next year, together for the first time since 1803. But this year, possibly as early as this weekend, a relatively small number of Magicicada septendecim may come out ahead of schedule:
Love them or hate them, Chicagoans might not have to wait another year to see the blood-red eyes of these polarizing creatures with orange wings. It often happens that a few hundred stragglers get confused and emerge a few years before or after they are supposed to.
Scientists are expecting an early emergence of brood XIII cicadas, which come out every 17 years, and of brood XIX cicadas, which come out every 13 years. The former can be found in northern Illinois, including the Chicago area, as well as in some parts of Iowa and northeastern Indiana. The latter can be found in various southern states, including south portions of Illinois.
“The (stragglers) are numerous enough to be noticeable but they also don’t really survive very long because the periodical cicadas sing during the daytime when birds and other predators are quite active, and they’re relatively obvious insects,” said Phil Nixon, retired entomologist from the University of Illinois at Urbana-Champaign.
[C]icadas usually come out after a day or two of high temperatures in the low 80s and low temperatures around the 70s, followed by rain that softens the soil. They emerge after soil temperatures exceed 64 degrees.
The Brood XIII emergence due a year from now in the Chicago area is expected to be the largest emergence of cicadas anywhere, with numbers approaching a million insects per hectare.