FRANKFORT, MI — An invasive pest which kills hemlock trees has been found in Benzie County; extending its march 50 miles north of the known infestation line near Ludington.
The Michigan Department of Natural Resources (DNR) said the hemlock woolly adelgid (HWA), a tiny insect which extracts sap from hemlock trees while slowly killing them, was found last month at the Crystal Downs Country Club near Frankfort.
On Jan. 27, the U.S. Dept. of Agriculture confirmed a sample collected by Northwest Michigan Invasive Species Network (ISN) staff who found the pest while conducting a survey.
The detection follows a 2021 discovery in single tree at a Sleeping Bear Dunes National Lakeshore campsite in Benzie County, although the DNR says no signs of the insect have arisen since that tree’s branches were removed.
“While no one welcomes the news that their trees are infested, we’re glad the survey found the infestation at an early stage so we can contain it and protect hemlock trees, which are an important part of our landscape,” said Michael Huget, Crystal Downs board president.
The country club is located north of Point Betsie between Crystal Lake and Lake Michigan. Invasive species surveyors are canvassing the club grounds to discover the extent of infestation and mark trees for treatment.
Similar surveys will happen elsewhere in Benzie County and along the lakeshore through March. The surveys are part of a larger, systematic effort along the Lake Michigan shoreline to find infestations before they become unmanageable.
Hemlock woolly adelgid is a small insect that uses long, siphoning mouthparts to extract sap from hemlock trees. This weakens needles, shoots and branches. Over time, growth slows and trees become grayish-green. Without treatment, infested trees die within four to 10 years.
Treatment involves a painstaking insecticide application.
The bugs pose a major threat to Michigan’s estimated 170 million hemlock trees, an evergreen that’s largely found along streams, rivers and coastal dunes in northern forests but which is also used in park and residential landscaping.
In the past six years, infestations have been confirmed in five counties along Lake Michigan: Allegan, Ottawa, Muskegon, Oceana and Mason.
In Michigan, the first detection was in 2006 in Emmett County, in nursery stock from Virginia that was planted in Harbor Springs. The bug was thought to be eradicated by 2015, but it returned later that year in Muskegon and Ottawa counties.
A native of Japan, it’s believed the adelgids first arrived in the United States in the 1950s in Virginia.
The Michigan Department of Agriculture and Rural Development (MDARD) regulates movement of hemlock nursery stock, forest products and yard waste in Allegan, Ottawa, Muskegon, Oceana and Mason counties.
Based on the new detection and overall winter survey results, the state says it will review whether to extend the quarantine boundaries northward.
Though the tiny insects don’t move far on their own, they can be blown by wind or hitchhike on birds or mammals that come into contact with an infested branch. Cars, boats or recreational vehicles parked under infested trees can also transport the insects to new locations.
Infestations are easiest to spot in the winter because cooler weather triggers production of the insects’ small, round, white ovisacs; where egg cells are produced.
Anyone within 10 miles of the shoreline in Benzie, Grand Traverse, Leelanau and Manistee counties with hemlock trees on their property is encouraged to request a site visit from invasive species surveyors by completing this form.
People spending time outside this winter are encouraged to look at the underside of hemlock branches for round ovisacs which look like spun cotton balls.
Infested trees should be photographed and reported with a detailed location by either emailing MDA-Info@Michigan.gov, calling 800-292-3939, or using the Midwest Invasive Species Information Network online reporting tool or smartphone app.
Do not collect samples.
The Northwest Michigan Invasive Species Network is offering adelgid survey training at no cost on Saturday, March 11, from 10 to 11 a.m. at Almira Township Hall in Lake Ann. Those interested in attending are encouraged to register at HabitatMatters.org/Events.
Related stories:
Tiny pest threatens to decimate Michigan hemlocks
Ad Choices