Groton — Wasps called "cicada killers" have burrowed into the sand at Poquonnock Plains Park, forcing the Groton Parks & Recreation department to block off the sandbox and play area used by children ages 2 to 5.

Jerry Lokken, manger of recreation services for Groton, said the insects have nested in the sand for the last three or four years in the popular park, and are also in part of the track. But he said the wasps are not dangerous; male cicada killers do not have stingers. Females have stingers but rarely sting, Lokken said.

"They're big and they look menacing, but they're really not," he said.

The female wasps prey on cicadas and feed them to their larva, according to nationalgeographic.com.

Lokken said insecticides would kill the adult wasps but not the eggs, so the insects would return to the park next year. He said the department decided not to treat the playground with pesticides because children play there. Lokken said the insects should disappear in about a month.

"Perhaps by September they'll probably be gone, and it'll be back to normal," he said

Parents with children at the park Monday said they were avoiding the area, marked with yellow tape and traffic barriers. Wasps hovered over the sand.

Julia Allen of Groton said the insects seem to stay confined, but she believes the department should put up a sign.

"Sand is what kids want to play in," Allen said.

Meghan Berry of New London said she's been visiting the park for years, and the wasps seem to return to the sandbox every summer.

"It's really frustrating because it's one of the nicest parts of the park," she said.

d.straszheim@theday.com