Christelle Guédot, a fruit crop entomologist and extension specialist in the Department of Entomology at the University of Wisconsin–Madison, says that Japanese beetles were once the bane of gardeners and farmers in the southern half of the state, but their range has since spread northwards.
“Over the past 10 years, they have been detected by the Wisconsin Department of Agriculture, Trade and Consumer Protection up in Bayfield. We also trap many hundreds in Spooner and we see them now in Door County,” Guédot said. The beetles have also been wreaking havoc in the northeastern counties, including Oneida and Vilas.