NATCHEZ — When Keith Sanders heard the loud vibrating chirp of winged insects during the daytime Tuesday, he knew visitors who wait more than a decade to visit the area — even though they never left — had returned.

The sound is the emergence of the 13-year-cicadas, a locust-like insect that, through its lifespan, emerges only once every 13 years.

“It sounded like thousands and thousands of them — maybe a million — were all singing at once,” Sanders said.

“They have a high trilling sound that kind of fades off and stops, but I have never heard anything from them like I have heard (Tuesday) and (Wednesday).”

The brood emerging in the area are different from the cicadas that emerge annually, Adams County Extension Service Director David Carter said.

“We see the green cicadas every year, and they are not uncommon,” he said. “But these are black with red eyes, and they are very different, and you’re going to find them in areas with more hardwoods.”

As adults, the cicadas sing in a manner similar to grasshoppers, Carter said.

“They have six different sounds they make with their wings,” he said. “Right now, they are in the top of trees, singing, mating and laying eggs.”

At the beginning of their lifecycle, the 13-year-cicadas hatch from egg nests mounted on living twigs, fall and burrow into the ground.

They age slowly under the earth, and 13 years later, they burrow back out of the ground, emerging as juvenile nymphs. After leaving the hole, they molt their skin as part of the final transition into adulthood, which begins four to six days later, after their new skin hardens into a shell.

After mating and leaving egg nests for the next generation, the adults die. Six to 10 weeks later, the eggs hatch, the cicadas burrow underground and the cycle starts over.

Another breed of cicada has a similar lifecycle on a 17-year rotation, Carter said.

The insects feed by sucking — not chewing — on hardwood trees and similar plant life, and don’t represent a risk to the area’s crops and decorative shrubbery, Carter said.

“They are not harmful at all, and my kids have caught tons of them,” he said. “If you want to catch one, don’t worry about climbing trees to get them, because they are going to be on the ground.”

Those who do find interesting cicadas can contact the extension service, Carter said, which is collecting specimens to send to the state museum.

The extension service can be reached at 601-445-8202.