By Bill McNee, DNR Forest Health Specialist, Oshkosh, bill.mcnee@wisconsin.gov or 920-360-0942

In 2021, emerald ash borer was found in 90 more communities in Wisconsin than in 2020, including 10 cities, 14 villages and 66 towns. This increased the total number of communities with a reported emerald ash borer detection 11% to 898 at the end of 2021.

Emerald ash borer was confirmed for the first time in Barron, Iron and Langlade counties during the year. It has now been found in 61 of Wisconsin’s 72 counties and confirmed on Oneida Nation land, and we believe additional unreported infestations are present.

Municipal emerald ash borer detections during 2021 are shown in orange. Older detections are shown in green or blue. Map courtesy of Wisconsin Department Agriculture, Trade and Consumer Protection.

By the end of 2021, the pest was found in 49% of all Wisconsin municipalities: 131 cities (69% of all cities), 236 villages (57% of all villages) and 531 towns (43% of all towns). The cities where it’s been found are disproportionately located in the southern half of Wisconsin, where emerald ash borer is now a common insect. In contrast, the northern half of Wisconsin has many towns, and emerald ash borer is much less common in that region and in that type of municipality.

Cumulative number of Wisconsin communities where emerald ash borer has been detected as of the end of 2021. Graph courtesy of Wisconsin DNR.

The five following communities are currently the most populous ones that are not on the state’s municipal detection lists: the village of Weston in Marathon County, the city of Menomonie in Dunn County, the city of Chippewa Falls in Chippewa County, the village of Plover in Portage County and the city of New Richmond in St. Croix County. However, emerald ash borer is likely present in some or all of these five communities.

Find additional information about emerald ash borer identification, detections and management here. Information for communities can also be found on the DNR’s urban forestry webpage.

Note: Emerald ash borer municipal information is from the master list maintained by the Wisconsin Department of Agriculture, Trade and Consumer Protection. Community information is from the Wisconsin Department of Administration, Demographic Services Center and uses estimated populations as of January 1, 2021.