Hemlock woolly adelgid (HWA) is an invasive insect native to eastern Asia that sucks sap from eastern hemlock tree branches and can kill a tree in 4 to 10 years if not treated.  HWA can be identified by its white, cottony ovisacs on the undersides of hemlock branches, near the base of the needles. The ovisacs may appear alone or in clusters. Late fall through early spring is the best time to check hemlock trees for the presence of HWA. You can see them with the naked eye or use binoculars to see higher branches.

Invasive hemlock woolly adelgid has been found in Mason County. Thanks to collaborative efforts between the Michigan Dept. of Natural Resources, regional CISMAs (Cooperative Invasive Species Management Areas) and regional Conservation Districts, HWA was located in Summit Township and Ludington State Park in 2020. Treatments have been underway in 2020, 2021, and 2022 to protect the infested trees and those in surrounding areas. In winter 2021-2022, Mason-Lake Conservation District staff found HWA in other locations in Mason county, mostly to the south of Hamlin Lake and west of Jebavy Rd, and also on the most easterly portion of the arm of Hamlin Lake.

Treatments are underway for the known infested trees and those in surrounding areas. Treatments are handled by West Michigan CISMA thanks to grants provided by the US Forest Service, and in 2022 the WMCISMA treatment crew will be joined by Mason-Lake Conservation District staff thanks to MISGP grant funding from the DNR.

Mason-Lake CD staff will continue detection survey efforts in 2022-23 for private property, local campgrounds, township parks, etc. to determine if HWA has spread to other areas of the county.  If located, this will trigger a regional response to containing the infestation and working with the landowner to provide treatment on infested trees. We do not want this insect to continue spreading north!

  • Contact usf or a free site visit to check out your trees. Just complete and return the permission form to us and we will schedule a visit. Completed forms can be mailed to the address on the form or emailed to This email address is being protected from spambots. You need JavaScript enabled to view it..

  • Keep an eye on your trees!  Look at undersides of branches in December through March for small, white ovisacs. If found, note the location of the tree and, if possible, take photos of the infested branch. To avoid spreading HWA, do not collect sample branches or twigs. Report the find using one of these methods:
      • Contact us via email at This email address is being protected from spambots. You need JavaScript enabled to view it., or phone (231) 757-3707 ext. 111
      • Use the Midwest Invasive Species Information Network (MISIN) online reporting tool or MISIN smartphone app.
  • Remove birdfeeders from areas where hemlock trees are present. Birds may carry these insects to a birdfeeder where they can be picked up and transported by other birds.

  • Be mindful of your hunting and camping gear, RV’s etc.  If you are in areas with hemlock trees, just brushing against an infested tree could bring these insects along for the ride! Run clothing through a dryer and wash or brush off gear and vehicles before moving to a new area.

  • Construction equipment could also spread these insects and other invasives. Ensure they are washed or brushed off before entering and leaving sites!

  • Consider pruning low-hanging hemlock branches especially along roadways or driveways.

  • For a two-sided, pocket sized HWA and hemlock tree identification card please contact our office to pick one up. Great to keep on your fridge as a reminder to check your trees!

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Please see the following resources for help with identification, information, and reporting options:

  • - A short video with identification tips.
  • Michigan.gov/HWA – website with identification, look-alike and quarantine information, maps and more.
  • SaveMiHemlocks.org – website of the West Michigan hemlock woolly adelgid taskforce