It's bug vs. bug in latest attempt to save ash trees
By Lee Bergquist
Town of Saukville
- Wisconsin's newest weapon in the war against the emerald ash borer took flight on Wednesday morning as tiny parasitic wasps were released into a forest infested with the invasive pest.
Two species of Asian wasps that feast on the larvae of the insect were let go by University of Wisconsin-Madison entomologists at the Riveredge Nature Center.
A third species that feeds on the egg stage of the bug will be released later this summer.
It was the first time that the wasps - which are invasive species in their own right - have been used in Wisconsin to fight the destructive pest.
Emerald ash borers have killed tens of million of trees since they were discovered in Michigan in 2002.
Thus far, some chemical treatments have shown promise for controlling the pest. They are largely used in residential settings, but not entire forests. Biological controls - in this case, an experiment pitting bugs against other bugs - would attack emerald ash borers in larger settings where chemical treatment isn't feasible.
UW-Madison entomologist Ken Raffa and a graduate student, Todd Johnson, released 800 wasps from plastic cups late Wednesday morning.
After a few feet of flitting through the air, they disappeared into Riveredge's forest, which is being hit hard by emerald ash borer.
This area along the Ozaukee-Washington county line is ground zero for Wisconsin's infestation.
The emerald ash borer was detected in 2008 in Newburg, where the skeletal remains of dead ash trees have become an all-too-common site.
Since then, they have been found in Cudahy, Franklin, Oak Creek, Green Bay, Kenosha and Victory in Vernon County. Wisconsin has an estimated 700 million ash trees.
As part of this year's experiment, all of the wasps will be released at Riveredge, where the insects will not need to travel far to find food.