Published on 08/13/03

Killer wasps swarm in August

By April Reese
University of Georgia

Measuring almost two inches long, sporting yellow markings across a robust body and patrolling the ground with red wings and yellow legs, cicada killer wasps look intimidating. Although they look fierce and threatening, they're more buzz than bite.

"Although these wasps are very large, they usually ignore people," said Nancy Hinkle, an extension entomologist with the University of Georgia College of Agricultural and Environmental Sciences. "The individuals patrolling the ground are males, which cannot sting and are harmless. Females are rarely seen because they are busy hunting cicadas and must be provoked to sting."

Lone flyers

Female cicada killers, also called giant cicada killers or sand hornets, use their stingers to paralyze cicadas, noisy insects that live in nearby trees.

"As big as female cicada killers are, they still have a hard time lumbering through the air with a cicada, so often they paralyze it, drop it from the tree, and then drag it along the ground," Hinkle said.

"Females are rarely seen because they are busy up in the trees, looking for cicadas to bring back and bury in the ground for their larvae to feed on," she explained. "While the females are capable of stinging, they are shy and must be forced to sting."

People who have caught female cicada killer wasps claim the sting is less painful than that of a wasp or bee, she added.

Cicada killers are solitary wasps, unlike most other wasps, such as hornets, yellow jackets and paper wasps who live in social groups. Cicada killers live in solitary units where each female digs her own burrow, six to 10 inches deep and as much as six inches horizontally, to lay her eggs.

They prefer to burrow in well-drained or sandy soils, making a horseshoe shaped mound beside the hole. Each burrow can have as many as 20 eggs, each in an individual cell, and each egg can have as many three cicadas to feed on in its cell.

"Cicada killer wasps show up around the first of August in Georgia and may be seen for about a month," she said. "By September, adult cicada killers will have mated, provisioned their burrows with cicadas for the larvae, laid their eggs, and died."

Cultural control

Although virtually harmless, cicada killers can invade your home landscape and make a mess with their horseshoe dens. If control is necessary, locate the nests during the daylight hours and treat after dark when female wasps are in their nests. Remember to wear protective clothing.

"These strikingly colored wasps are particularly noticeable because of their size and the fact that they fly close to the ground," Hinkle said.

Before deciding to do away with the insects, Hinkle urges you to remember, "as is apparent from their name, they are predators on cicadas, so they provide good biological control of these pests of ornamental trees and shrubs."

The best control is prevention. Because cicada killers nest in open areas without vegetation, healthy turf won't be attacked. The best way to prevent having cicada killers around is to cultivate a lush healthy lawn without bare patches.

"So, remember, the more aggressive cicada killers are males, which are all show and no substance. They hope to be able to scare you away by bluffing, but when it comes down to it, there's nothing they can do to you - or any other predator," she said. "The females are otherwise occupied and can't be distracted, so pose no threat. Because they are so innocuous - and so beneficial - it is best to leave them alone and just enjoy their beauty and fascinating behaviors."