MAPLE, Wis. 鈥� Douglas County in Wisconsin is going to work with the U.S. Department of Agriculture to save ash trees.
On Monday, Dec. 18, the Douglas County forestry committee approved the USDA Animal and Plant Health Inspection Service to release parasitoid wasps on 20 acres of land in the town of Maple to combat emerald ash borers.
ADVERTISEMENT
The invasive beetle was first discovered there in 2021, eight years after it was found in Superior.
The stingless wasps were found to be a natural enemy of the emerald ash borer (EAB), according to the USDA. Four wasp species 鈥� three that attack the larvae and one that targets EAB eggs 鈥� kill the invasive beetle, the USDA reported.
A study conducted in Michigan and several northwestern states showed the wasps killed 20% to 80% of emerald ash borer in ash trees up to eight inches in diameter, resulting in fewer EAB attacking the trees, according to a USDA report issued in December 2020.
鈥淪ome of the trees are significantly damaged, but there is a portion that would be a good candidate for the release of the wasps,鈥� said Mike Nordin, a USDA technician based in Duluth. 鈥淲e have released wasps in other parts of Wisconsin. 鈥� It鈥檚 a biological control.鈥�
The releases would occur monthly on county forest land near County Highway O from June to September in 2024 and 2025.
鈥淚t was pretty morbid what you were telling us, that we鈥檙e going to lose every ash known to mankind on the North American continent,鈥� said Mark Liebaert, Douglas County board chairman. 鈥淒oes this give us hope that they鈥檙e going to survive?鈥�
Based on what鈥檚 happening on the East Coast, where the wasps have been used longer, Nordin said saplings and seedlings are doing better since the introduction of the wasps.
ADVERTISEMENT
鈥淚 think it鈥檚 a real great deal,鈥� Supervisor Nick Baker said, making the motion to approve the release of the wasps.
The Trust Project
