Maybe you haven’t seen them, with their dark green hard-shell bodies and large red eyes, but you may be hearing the trademark buzzsaw sound of the cicada.

The insects have made headlines for months because the emergence of two broods — an occurrence two centuries in the making — is expected to bring astronomical numbers of these insects above ground. The group of cicadas known as Brood XIX emerge every 13 years. This is also the year for Brood XIII, to emerge after 17 years underground.

“Over the next few months, people in the South will witness the emergence of the largest brood of periodical cicadas in the country, spanning parts of 16 states,” said Jon Zawislak, extension urban entomologist for the University of Arkansas System Division of Agriculture.

“The insect army poised to invade are still nymphs, in the very last stage of their development,” he said “After feeding on fluids from tree roots for 13 years, slowly growing and molting underground, they will make their debut by crawling up and out of the soil when it warms to about 64 degrees Fahrenheit and is softened by rains.”

The adult cicadas pose no threat to people, pets or livestock. They don’t sting and don’t bite.

“Mature adults don’t feed and don’t even have functional mouthparts with which to bite,” Zawislak said. “Having spent the last 13 years doing little more than eat, they emerge with the single-minded goal of making more cicadas.”