If you live in one of the lucky (or should we say unlucky?) states, this spring is bringing a once-in-a-lifetime event just outside your window.

Starting in mid-May, 16 states in the South and Midwest will experience the emerging of two different cicada groups simultaneously, something that hasn’t happened in 221 years and won’t again until 2245.

The two groups, Brood XIX and Brood XIII, are periodical cicadas that typically emerge separately every 13 and 17 years, respectively.

But this year, they will emerge from their years spent underground together.

See the map of states where the different cicada broods will emerge

According to the map, Oklahoma’s most prevalent brood of periodical cicadas is Brood IV, which last emerged in 2015 and is next expected in 2032.

Brood XIX will make an appearance in southeastern Oklahoma, specifically McCurtain County. Brood XIX is also the largest known group of periodical cicadas, stretching across 14 states.

In total, Brood XIX and Brood XIII will emerge in 16 states this year:

• Alabama

• Arkansas

• Georgia

• Illinois

• Indiana

• Iowa

• Kentucky

• Louisiana

• Mississippi

• Missouri

• North Carolina

• Oklahoma

• South Carolina

• Tennessee

• Wisconsin

• Virginia

What are periodical cicadas?

As opposed to annual cicadas which emerge every year, periodical cicadas emerge every 13 or 17 years, according to the U.S. Environmental Protection Agency.

According to OSU Extension, periodical cicadas have the longest life cycle of any known insect because of their years spent underground.

When the time comes, periodical cicadas will emerge from the soil at night, shed their skins and spend around a month eating, mating and, for females, laying eggs before dying.

When those eggs hatch, they become nymphs that will fall to ground and burrow deep under the soil. During that time, they will feed on tree sap from underground roots and in 13 or 17 years, the cycle will repeat itself.

This article originally appeared on Oklahoman: 2024 cicada map: See where historic broods will emerge this spring