Illinois residents can look forward to an unusually noisy spring, as billions of periodical cicadas are set to emerge in a rare "double-brood" that will overlap in the central region of the Prairie State.
Beginning in April, Brood XIII and Brood XIX will emerge in the central and southern regions of the country. The Brood XIII cicadas were born in 2007 and spent 17 years growing underground, while the Brood XIX cicadas were born in 2011.
While cicadas regularly emerge in 13-and-17-year cycles, it is rare that the two cycles happen concurrently - in fact, it's a once-in-every-other-lifetime phenomenon. The last time the US saw two overlapping broods was 1803 and it's not expected to happen again until 2245, according to the Independent.
"I've been looking forward to this for years," Illinois entomologist Catherine Dana told Scientific American. "We have two different broods emerging in the same state, and that's a very rare thing."
Scientists even believe that cicadas from the two different broods could interbreed - though they are different species, with the males singing different versions of the insects' characteristic songs, according to Scientific American.
Though only Illinois will see the broods overlap, large swaths of the country will see the emergence of new cicadas, as the warmer months begin. Brood XIII is found in Illinois, Iowa, Wisconsin and Indiana.
Brood XIX, meanwhile, is present in Alabama, Arkansas, Georgia, Indiana, Illinois, Kentucky, Louisiana, Maryland, Missouri, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee and Virginia.
"They don't often coincide in time, but to have them coincide in time and space is even more unusual," insect ecologist John Lill told Scientific American. "That's what's happening this year that's generating a lot of buzz-pun intended."
