The Muskegon Conservation District urges local citizens to be aware of hemlock woolly adelgid and the ways to treat their trees if hit by an outbreak.
Hemlock woolly adelgid (Adelges tsugae) is an invasive forest pest that attacks eastern hemlocks and has the ability to devastate Michigan’s estimated 170 million hemlock trees. Once infested, hemlocks have a 4-10 year life expectancy.
Look for hemlock woolly adelgid (HWA) on the underside of the hemlock branches at the base of the needle. Though the insects are hard to see, HWA can be identified by its white, woolly egg masses (ovisacs) that look like tops of cotton swabs. Hemlocks are vulnerable to HWA at any stage of growth. Hemlock woolly adelgid can be transported to new locations by birds, wildlife, wind, field equipment such as trucks and campers, clothing, infested yard waste and nursery stock. This pest is most easily transferred from April through July, with their feeding cycle happening during the winter months.
Hemlock forests along the Lake Michigan shoreline have been hit hard by HWA, with infestations in 10 counties as of 2024, including Muskegon and Oceana. These forests are ecologically important due to the unique environmental conditions they create under dense canopies and are critical to the survival of a variety of species that rely on hemlocks for protection, food, and growing conditions. Hemlocks on your property help create a beautiful, healthy ecosystem and can increase property value. The loss of Michigan’s hemlock resource could result in a dramatic change in ecosystem processes, which in turn could cause a disappearance of unique plants and wildlife.
To combat this invasive, chemical treatment is recommended to treat HWA. Trees can be treated with systemic insecticides called Dinotefuran (up to one to two years of protection) or Imidacloprid (up to five to seven years of protection). Without treatment, hemlocks will succumb to this forest pest. There are a variety of businesses that can perform the treatments for-hire. The Muskegon Conservation District has a treatment program for HWA. We are skilled and certified using both types of insecticides and have spots available for our 2025 treatment season. The cost of treatment varies from property to property and is dependent on the number of trees and the average size of those trees. The quote to estimate cost is free and you can sign up for this service on the MCD website at muskegoncd.org under projects and programs. Here you can also find more information about our treatment program and the process! You can also contact Lance McCarty at lance.mccarty@macd.org or call the MCD office at 231-828-5097 with any questions.
We can all work together to protect Michigan’s hemlocks.
