Cicada broods XIX and XIII both emerged in the same spring and summer this year, and the regions in the Midwest where descendants of the two broods overlap are now inundated with buzzing cicadas everywhere, writes Jane Nash in the award-winning student newspaper at Prospect High School in Mt Prospect, Illinois.
Map: Library of Congress (public domain). Overlays based on a New York Times graphic.The map shows the United States around 1803, with Brood XIII shown in yellow around Ft Dearborn, near Chicago, and Brood XIX shown in green just south of Brood XIII and extending somewhat west of it and to the East Coast. The zones of these cicadas have expanded over the years and now have significant overlap in their coverage area.
Since 1803, 13 generations of the cicadas of Brood XIII with their 17-year lifespan and 17 generations of the cicadas of Brood XIX with their 13-year lifespan have come and gone. Descendents of these two broods will next emerge from the warming ground to molt, sing, mate, lay eggs, and die during the same summer in 2245.
“I think it’s so fascinating that nature can create a life process that takes 17 years to blossom for a mere two weeks before the cycle repeats itself,” the paper quoted a resident as saying. “I find this to be an amazing and beautiful life cycle.”
Indeed, there are many theories about how this unusually long lifecycle evolved, with some scientists suggesting a selective advantage to the prevalence of prime numbers in the lifecycles, producing very infrequent simultaneous emergence.
As most Illinoisans know, the cicadas are helpful, not harmful, except perhaps to young trees, mostly from when the females slit notches in branches to lay eggs.
“I frankly think that just seeing cicadas everywhere I go is kind of crazy and scary all in the same place,” the paper quoted one ninth grader as saying. “I guess it’s really part of the Midwest experience. I’m not too scared of bugs, but if you told me it was an apocalypse, I’m already in Canada.”
