(Gray News) – The cicada invasion has started in the southeast, as the bugs are about to emerge in numbers we haven’t seen in decades.

On Sunday, Brad Buchanan posted a video on X showing cicadas crawling up a tree in Charlotte, North Carolina.

“That long-warned-about cicada invasion is here,” he wrote in the post.

Experts said this is the first time in centuries that billions of cicadas will take to the air as the life cycles of two different broods overlap.

According to researchers, 13-year broods, Brood XIX, usually emerge in the same year as a 17-year brood, Brood XIII, every five to six years. These broods are usually not in contact with each other, however, and are spatially separated.

A co-emergence involving adjacent broods of two different life cycles only happens once about every 25 years, and two specific broods of different life cycles co-emerging only happens once every 221 years.

Experts say the co-emergence involving the specific broods of XIX and XIII is the first since 1803. The next co-emergence won’t happen until 2037.