This spring, a rare event will unfold as two cicada broods with 13 and 17-year cycles emerge simultaneously, last seen in 1803. The billions of insects will create a unique spectacle, according to an NBC News article. They say, 

“This spring, two different broods of cicadas — one that lives on a 13-year cycle and the other that lives on a 17-year cycle — will emerge at the same time from underground in a rare, synchronized event that last occurred in 1803.

Billions of the winged insects will make an appearance across the Midwest and the Southeast, beginning in some places in late April, for a raucous mating ritual that tends to inspire fascination and annoyance in equal measure.”

While cicadas emerge annually, periodical cicadas with 13 or 17-year cycles surface in a synchronized event. Brood XIII and Brood XIX will align this year, a rare occurrence, according to a Smithsonian Magazine article. It says, 

“Though some cicadas surface every year, periodical cicadas spend most of their lives underground before emerging en masse every 13 or 17 years to mate and start the cycle over again.

Any pair of broods may occasionally overlap and emerge in the same year. But these specific groups—Brood XIII (also known as the Northern Illinois Brood) and Brood XIX (or the Great Southern Brood)—only appear simultaneously once every 221 years, making 2024 an especially exciting period for entomologists and bug aficionados alike.

The next time the broods align again will be in 2245.”

Entomologist Floyd W. Shockley emphasizes the unique nature of the cicada event, stating that witnessing such a synchronized emergence won’t occur again in anyone’s lifetime.