LANSING, Mich. – The Michigan Dept. of Natural Resources (DNR) has reported a find of Hemlock woolly adelgid (HWA) well north of where the invasive pest has typically been found in Michigan.

The new find is in Benzie County, Mich., about 50 miles north of what was previously thought to be the northern edge of infestation, in Mason County, Mich. Both counties hug the Lake Michigan shoreline, as Hemlock trees favor the environment near the lake and other waterways. The Northwest Michigan Invasive Species Network staff members conducting a winter survey for the pest detected the tiny insects on Hemlock at Crystal Downs Country Club in Frankfort in late January. The only other time this happened in Benzie County was in 2021, where a single tree infested with HWA was found at a campsite at the Sleeping Bear Dunes, however, no other trees were found with it in the area. HWA is a tiny insect that uses its long, siphoning mouthpart to extract sap from Hemlock trees, over time this weakens the trees and will kill them if not treated. HWA is an invasive pest and native to Asia and is characterized by tiny white formations on Hemlock twigs that can look like cotton balls.

There are 170 million Hemlock in the state and they are used extensively by greenhouses for sale to individuals for landscaping as well as to businesses, according to Joanne Foreman, a spokeswoman for the Michigan Dept. of Natural Resources. “We have been looking on the shoreline and 10 to 15 miles inland,” Foreman said. “Although the Hemlock prefer hilly areas to grow, there are many orchards and farms in western Michigan, so undoubtedly there are some Hemlock that grow on farmland in the area. Tree farms also sell Hemlock as landscaping trees for people’s yards and to some businesses. Conservation districts have annual tree sales, also, as fundraisers and sell Hemlock trees to both residential as well as businesses.” Foreman added that businesses and area nurseries in particular have been participating in efforts to stop the spread of HWA.

Mason-Lake County Conservation District HWA Project Manager Brie Jasinski said, “we are actually a big part of the effort to control HWA in Michigan. We do have annual tree sales as fundraisers, but right now we aren’t selling Hemlock seedlings. We’re doing a lot of detection surveys in Mason County. We try to advertise that this is a service that we offer.” The group reaches out to mostly residences, but sometimes does a survey at a township or county park to see if any HWA might be lurking there. According to Jasinski, the conservation district might do a survey at an area farm if there is a waterway running through the property. “If we find HWA on someone’s property, if it’s on the northern edge of where HWA is occurring then there is some grant money available to treat the infestation. But that funding might not last. If it’s found in the more southerly counties where HWA is more common, then we can’t pay for treating those infestations.”

HWA was first detected in Michigan in 2015. Although it is slow moving, it has gradually moved north along the Lake Michigan shoreline. The tiny adelgid – like an aphid but confined to conifers – can reach the moth stage in its native Asia, but lacks the right host here and never reaches the moth stage in Michigan, remaining always as a crawling rather than flying pest. People who live near the Lake Michigan shoreline are encouraged to have their property surveyed for HWA. More can be found out about this at HabitatMatters.org or at MichiganInvasives.org.