Wisconsin DNR says emerald ash borer find in Burnett County means beetle has spread across state

The tree-killing emerald ash borer has now spread to every county in Wisconsin, state officials said Friday.

The state Department of Natural Resources said agency staff responded to a report of a possible emerald ash borer infestation in two trees at a private residence in the town of Meenon in Burnett County on June 13.

Tests the U.S. Department of Agriculture Animal and Plant Health Inspection Service conducted on insect samples taken from the trees confirmed the specimens were emerald ash borer.

Ashland has taken action to protect trees in the city from the infestation. As part of its fight, the city is treating dozens of trees infected with bugs. The city has about 575 public trees in right of ways, boulevards and city parks. In 2022, about 60 ash trees found to be in poor to fair health were removed and 42 trees were planted.

Starting in 2023 and running through 2025, roughly 60 trees in poor to fair condition will be removed each year, 55 trees will be planted and 100 trees will be treated by a contractor with a 4% emamectin benzoate solution. When sprayed on foliage, emamectin benzoate penetrates leaves and forms a reservoir within them, which provides residual activity against pests, according to Environmental Protection Agency.

The emerald ash borer is native to Asia. It was discovered in the United States in southeastern Michigan in 2002. Officials believe the beetle has been moving around the country by hitching rides on firewood.

According to the USDA’s Animal and Plant Health Inspection Service, it is currently present in 36 states and the District of Columbia. It was first discovered in Wisconsin in 2008 in Ozaukee County.

Emerald ash borer larvae bore into ash trees, killing them. The DNR expects that the beetle will eventually kill more than 99% of Wisconsin’s white, black and green ash trees.

The Associated Press contributed to this story.