Lake County battles ash borer with predator wasps

Can a natural predator be the answer in the fight against the destructive emerald ash borer?

The Lake County Forest Preserve District wants to find out and plans to release up to 2,700 tiny predator wasps this summer in a forest preserve along the Des Plaines River.

“In my opinion, this is a very good avenue to look at,” said Jim Anderson, the district's natural resource manager.

“We're going to try to build up a (wasp) population to keep the emerald ash borer in check,” he explained in a request for direction Monday from the forest board's planning and restoration committee.

The district, like many communities in Illinois, stands to lose a significant number of ash trees as the metallic green beetle spreads.

“There's nothing preying on it so it's going wild,” Anderson said of the emerald ash borer.

Forest district officials likened the use of the wasps for “biological control” to that of a program it began 10 years ago that uses beetles to control purple loosestrife, an invasive plant.

The forest preserve district would be working with the U.S. Department of Agriculture to obtain and monitor three types of wasps, known as parasitoids, in a test area between Wadsworth Road and Grand Avenue.

Anderson said they are less than a millimeter in length, can't sting or bite and were found to pose no risk to human health.

They were found to attack larvae or egg of the emerald ash borer in its native range in China, according to the USDA, and are being use in several states as a long-term strategy.

The invasive wood boring beetle was first identified in the U.S. in 2002 near Detroit and has spread to 13 states, including Illinois, killing tens of millions of trees in the process.

The USDA began releasing the three wasp species in small numbers in 2007 near its biological control facility in Michigan. Last year, the wasps were released in eight states, including Illinois.

The Chicago Bureau of Forestry is in its third year of releasing the wasps. Current and previous release sites include city parks, Cook County forest preserves and in Evanston, but the success of the program is yet to be determined.

There will be no cost to the Lake County Forest Preserve District, although it will be required to monitor to determine the success of the release of the wasps and their effectiveness.

Even if it does work, the results will be hard to gauge and could take years to determine.

“In 10 or 15 years, we may have more ash trees standing than we would have,” said commissioner Bonnie Thomson Carter of Ingleside, who chairs the planning and restoration committee.

Some committee members were concerned about the potential impact the wasp.

“It's just scary to introduce something ... “ said committee member Michelle Feldman of Deerfield. Feldman was the lone dissenter in a 6-1 vote, saying she wanted to study the data.

“Is there anybody out there saying this is a bad idea?” asked Pat Carey, a committee member from Grayslake.

“No,” Anderson replied.