ST. LOUIS -- Entomologists are predicting a noisy summer in Missouri as two broods of long-living cicadas emerge.

A batch that spent 17 years underground will make a ruckus in the northwest part of the state, while another group will surface in the southeast part after a 13-year subterranean existence.

Rob Lawrence, a forest entomologist for the Missouri Department of Conservation, said "it could be deafening" as male cicadas try to attract mates.

The cicadas' emergence will mark the only time this century a 13-year and a 17-year brood are arriving at the same time in Missouri. And it will be another 221 years before these two broods come out to mate at the same time in the state.

"When people think of cicadas in the summer, they usually hear one or two, and it's usually in July or August," Lawrence said. "This is going to be much different. Much louder, and earlier, like May and June."

The exact population of a brood is unknown, but researchers say the numbers can range from 10,000 cicadas per acre to 1.5 million an acre.

The 13-year brood already is singing in Mississippi and Tennessee. Blake Layton Jr., an entomology professor at Mississippi State University, said there have been a "lot of calls" as people see large black insects with red eyes flying around.