Crawling out from underground every 13 or 17 years, the periodical cicadas are nature’s kings of the calendar.

This spring, an unusual cicada double dose is about to invade a couple parts of the United States in what University of Connecticut cicada expert John Cooley called “cicada-geddon.” The last time these two broods came out together in 1803 Thomas Jefferson, who wrote about cicadas in his Garden Book but mistakenly called them locusts, was president.

The largest geographic brood in the nation – called Brood XIX and coming out every 13 years – is about to march through the Southeast, having already created countless boreholes in the red Georgia clay.

Soon after the insects appear in large numbers in Georgia and the rest of the Southeast, cicada cousins that come out every 17 years will inundate Illinois. They are Brood XIII.

An even bigger adjacent joint emergence will be when the two largest broods, XIX and XIV, come out together in 2076, Cooley said: “That is the cicada-palooza.”