By Lee Bergquist of the Journal Sentinel

Minnesota officials on Wednesday began releasing thousands of
parasitic wasps on an island in the Mississippi River to help fight
the spread of the destructive emerald ash borer.

Meanwhile, Wisconsin authorities said that this past summer's
surveillance found no new infestations of the tiny invasive beetle.

The stingless wasps were released on a Minnesota island, a few hundred
yards from Victory, a community in Vernon County where emerald ash
borer has attacked local ash trees.

Minnesota authorities have confirmed infestations in Houston County,
across the river from Victory, and in Hennepin and Ramsey counties in
the Twin Cities.

As part of efforts to control the spread of the bug in Minnesota, two
species of stingless wasps were introduced to the island.

The wasps were raised by the federal Animal and Plant Health
Inspection Service at a laboratory in Brighton, Mich.

Wisconsin authorities are considering using the wasps, but the
earliest it would happen is 2011, said Jennifer Statz, emerald ash
borer coordinator for the Wisconsin Department of Agriculture, Trade
and Consumer Protection.

Statz said Wisconsin's scientific panel is still weighing the merits
of using wasps, because it means introducing an invasive species into
the environment. Both the emerald ash borer and wasps are natives of
Asia.

Still, she said Wisconsin supports Minnesota's decision.

In the United States, the emerald ash borer has no known predator.

Enter the wasps, which lay their eggs next to the eggs of the emerald
ash borer and eat ash borer larvae under the bark of ash trees.

Statz said Wisconsin officials were surprised there were no new
infestations of emerald ash borers this year. The insect was
discovered in Wisconsin in 2008.

"It was a very quiet summer," she said.

She said experts with the agriculture department, the Department of
Natural Resources and the University of Wisconsin System aren't sure
why the bug didn't appear to spread this year, but one explanation may
be that higher-than-average temperatures limited movement this year.

The areas infested by the bug are: Newburg and the immediate
surrounding area in Ozaukee and Washington counties; Franklin, Oak
Creek and Cudahy in Milwaukee County; and Brown and Kenosha counties.