Maine has become the first state to employ wasps as unwitting scientific accomplices.

For volunteers with nets, ready to spring at a moment’s notice, it’s a project to protect the Maine woods from voracious beetles.

For the wasps — suddenly knocked out of the air, paralyzed beetle prey wrenched from their wasp arms, then just as suddenly let go — it’s a bit what-just-happened?

State forest entomologist Colleen Teerling has spent part of the summer training volunteers and pairing them with colonies of cerceris fumipennis, a ground wasp whose young dine on shiny, wood-boring beetles and — happily for volunteers — don’t sting.

The effort, Teerling said, is all about keeping an eye out for the green metallic emerald ash borer, a beetle that’s destroyed millions of trees in North America but hasn’t been found in Maine, yet.

Early detection could be the difference between having to cut down hundreds of trees versus thousands, she said.

“Maine is at the forefront,” Teerling said. “Bio-surveillance is completely new.”

Sarah Walton of Mechanic Falls led the first of the teams around the state to bag 50 beetles. In early August she darted around a field at the Poland Community School, blue net in hand.

“I just don’t want the trees to go away,” said Walton, 10.

She learned to be patient and look for “wasps that are really fat and they’re shiny,” signs that they’d gone into the ash trees and grabbed a wood-boring beetle.

“Sometimes they don’t (let go), and you’ve kind of got to give them a gentle flick to make them let go. They’re stubborn,” she said.

Walton picked beetle collecting as a project toward her Girl Scout Bronze Award after her troop got a visit from Teerling. Other Scouts also helped out.

“Last year, she was using butterfly nets to try to catch chipmunks,” said mom Joan Walton, leader of Troop 1600.

None of their beetles turned out to be emeralds, just nonthreatening members of the same family.

Teerling said the idea for using wasps originated with Canadian Philip Careless about 18 months ago. Temporarily bagging wasps to catch the beetles works well, she said, because the emerald ash borer starts feeding on a tree at its top, where people don’t climb and don’t notice, but wasps do.

“It’s often 10 to 12 years before people find it,” Teerling said. “Each one does a little damage. It’s when you get hundreds that they kill the tree — and they always kill the trees.”

People inadvertently spread the beetle by transporting firewood — a potential home for beetles — from place to place, Teerling said, making the state, with so much camping, vulnerable.

This month volunteers are at 20 sites. They got a late start because the wasps like to fly on clear, hot days, and it hasn’t been that sort of summer.

When they hunt, lady wasps grab a metallic beetle. (It aims for wood-borers but has been caught by volunteers making mistakes, like bagging a shiny Japanese beetle instead, Teerling said.) Lady wasps paralyze the bug, stuff several in an underground chamber, lay an egg on the last beetle and seal the chamber up. Eggs hatch over the next week or two, she said, and dine in-house for the next month.

Gathering 50 beetles from each site is enough to know whether emerald ash borers are present, she said, without infringing on the wasps too much. Collected bugs are frozen — that kills them — then mailed to the Maine Forest Service for positive identification.

“I’m hoping to have a network of colonies all throughout the southern half of the state and basically have an early warning network,” Teerling said. “All New England is going this way, but they’re where we were last year.”

Walton, who’s going into the fifth grade at Elm Street School, said she liked working with Teerling. And the bugs weren’t bad. “Some of the girls in my class would probably be screaming,” she said.

kskelton@sunjournal.com

For more information on Philip Careless’ research: www.cerceris.info