REGION– The Michigan departments of Natural Resources and Agriculture and Rural Development encourage those who have eastern hemlock trees on their property to take time this winter to inspect the trees for signs of hemlock woolly adelgid. Anyone taking to the woods also can help by looking for signs of this invasive insect while hunting, hiking or enjoying other outdoor activities.
Winter is the best time to look for evidence of an infestation, according to Robert Miller, MDARD’s invasive species prevention and response specialist.
“Cooler temperatures trigger feeding activity,” Miller said. “As hemlock woolly adelgid feeds, it secretes a white, waxy material that creates ovisacs. The presence of these small, round, white masses makes it possible to identify infested trees.”
As they feed, these tiny, soft-bodied insects consume a hemlock’s stored nutrients, slowly sucking the life from the tree.
These insects are considered invasive because they are not native to the state and can cause significant harm to Michigan’s estimated 170 million hemlock trees.
Infestations of hemlock woolly adelgid have been confirmed in Allegan, Benzie, Mason, Muskegon, Oceana, Ottawa and Washtenaw counties.
Since adelgids feed and form ovisacs only on eastern hemlock trees in Michigan, it is important to distinguish hemlocks from other conifers like pines or spruces.
Look for:
- Cone- or egg-shaped trees up to 75 feet tall.
- Drooping or feathery branches.
- Flat needles growing individually from the sides of twigs.
- Needles that are dark green on top with two parallel, white stripes underneath.
- Papery cones about three-quarters of an inch long that hang downward from branches.
Late fall through early spring is the best time to check hemlock trees. Look on the undersides of branches for evidence of round, white ovisacs near the base of the needles.
Up close, ovisacs look like tiny cotton balls and may appear alone or in clusters. The short video “Hemlock woolly adelgid: invasive species in Michigan” provides helpful identification tips.
Report infested hemlock trees by using the Midwest Invasive Species Information Network, available online at MISIN.MSU.edu or as a downloadable smartphone app. The MISIN smartphone app will take a GPS location point if a report is made at the site; it also will allow you to upload photos with a report.
Reports also can be made by email to MDA-Info@Michigan.gov or by phone to MDARD’s Customer Service Center at 800-292-3939.
