MADISON — The Wisconsin Department of Natural Resources (DNR) confirms the detection of emerald ash borer (EAB) in Burnett County, which means the pest has now been confirmed in all 72 of Wisconsin’s counties.

DNR staff responded to a report of EAB at a private residence in the town of Meenon on June 13. Two trees on the property showed characteristic symptoms of EAB infestation, including tree decline and visible woodpecker damage to the outer bark, known as “flecking.”

DNR staff members collected samples from the symptomatic trees and sent them to the United States Department of Agriculture Animal and Plant Health Inspection Service for identification. In July, the Animal and Plant Health Inspection Service confirmed that the insect specimens taken from the trees were emerald ash borer.

The state’s first confirmed sighting of EAB took place in Ozaukee County in July 2008. Although the ash tree-killing beetle is less established in northwest Wisconsin than in other parts of the state, this year’s detections indicate that the pest is expanding its foothold in the region. EAB is usually transported to new areas by hitching a ride on firewood.

EAB larvae bore into ash trees and carve winding, S-shaped galleries beneath the trees’ bark, typically starting in the upper canopy and progressing down the tree. The galleries restrict the movement of water and nutrients to affected areas of the tree, leading to branch dieback, canopy thinning and tree death.

EAB is expected to eventually kill more than 99% of Wisconsin’s white, black and green ash (and their ornamental varieties). Landowners concerned about EAB should contact a forestry professional or ISA-certified arborist and consult the state’s EAB Information Resource webpage to learn about management options. In the parts of northern Wisconsin where EAB populations remain low, there is still an opportunity to reduce the insects’ impact.

The Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) monitors the presence of EAB in Wisconsin. DATCP will continue to track the spread of EAB at the township and municipal level to inform management efforts to slow the spread. Visit the Wisconsin EAB Online Detections map to see where EAB has been found in Wisconsin or to report new detections.

The Burnett County detection will not result in any federal regulatory changes. EAB was federally deregulated on Jan. 14, 2021, and Wisconsin rescinded its state quarantine on July 1, 2023.

For more information, visit the DNR’s Emerald Ash Borer webpage or download the Emerald Ash Borer fact sheet.