COLUMBIA, S.C. – The din begins this spring.
A swarm of critters that emerges from underground every 13 years will fill the air over much of the Southeast with their ear-splitting mating calls.
Scientist call them periodical cicadas, Brood 19. Writers often mislabel the red-eyed, 1 1/2-inch-long insects as locusts, as in biblical plagues.
As ground temperatures approach 64 degrees, the four species of 13-year cicadas will dig out at night from burrows where they have sucked sap from roots for more than a decade.
Entomologists don’t know exactly what triggers their emergence, but the date does not vary much among generations.
“Periodic cicadas are amazing in their ability to be synchronized,” said Clemson University entomologist Eric Benson. “Almost overnight, tens of thousands emerge in an area. It’s something to behold.”
He predicts the swarms will rise about late April or early May, based on weather conditions in the spring and their behavior in 1998, the year of the most recent emergence. Other species of smaller cicadas come around every year.
Concentrations of the 13-year variety have been known to reach 1.5 million per acre in some places. But more commonly, the density is in the hundreds of thousands per acre, scientists say.
City slickers are less likely to notice the bugs. The cicadas stay where there are lots of trees and shrubs and the soil is undisturbed. They favor hardwoods and have a particular taste for oaks.
The insects are relatively harmless, scientists say. They are not poisonous. They don’t transmit disease. There are so many cicadas that nature allows hungry animals to feast until they’re full. But that still doesn’t significantly reduce the population.