It’s time to check your hemlock trees.



The Michigan Department of Natural Resources, Agriculture and Rural Development will ask those who have eastern hemlock trees on their property to take time this winter to inspect their trees for signs of hemlock woolly adelgid. I encourage you to do so. Anyone who goes to the woods can look for signs of this invasive insect while hunting, hiking, or enjoying other outdoor activities.

Round white hemlock woolly egg sacs are found on the underside of the branches near the base of the needles.

Round white hemlock woolly egg sacs are found on the underside of the branches near the base of the needles.

Winter is the best time to look for evidence of an invasion, said Robert Miller, MDARD’s invasive species prevention and response specialist.

“Cold temperatures induce feeding activity,” Miller said. “When hemlock woolly adelgid feeds, they secrete a white waxy substance that forms egg sacs. The presence of these small round white masses makes it possible to identify infected trees.”

These small, soft-bodied insects consume the nutrients stored in the hemlock as they feed, slowly sucking the life out of the tree.

These insects are not native to Michigan and are considered invasive because they can cause significant damage to Michigan’s estimated 170 million hemlock trees.

Hemlock woolly adelgid infestations have been confirmed in Allegan, Benzie, Mason, Muskegon, Oceana, Ottawa, and Washtenaw counties.

Winter survey underway

Throughout the winter, expeditions from the DNR and several cooperating invasive species management areas conduct surveys for signs of hemlock within a five-mile boundary along the shores of Lake Michigan.

Appropriate insecticide treatments can protect hemlock trees from these pests, so map and tag infected trees and other hemlocks in the area and prioritize them for summer treatment. Attach.

CISMA will seek permission from landowners to conduct hemlock surveys on private land within the shoreline boundary. CISMA’s research efforts are supported by funding from the Michigan Invasive Species Grant Program and the U.S. Forest Service, and are provided at no cost to landowners.

i need your help

Dozens of staff members help with the survey, but they cannot test every hemlock. If you have hemlock growing on your property, whether within or beyond the eight-mile shoreline boundary, take the time to look for signs of hemlock woolly his adelgid. Anyone who spends time outdoors is encouraged to do the same.

In the forests of northern Michigan, hemlock trees can be found in moist soils along streams, riverbanks, and coastal dunes. Hemlock is also popular as a landscape tree in parks and residential areas.

Identify Hemlock Trees

It is important to distinguish hemlock from other conifers, such as pines and spruces, because adelgid only feeds and forms egg sacs on eastern hemlock trees in Michigan. search:

  • A conical or egg-shaped tree up to 75 feet tall.
  • drooping or pinnate branches.
  • Flat needles grow individually from the sides of the twigs.
  • The needles are dark green at the top and have two parallel white stripes below.
  • They are paper-like cones about three-quarters of an inch long that hang downward from the branches.

look for signs

Late fall to early spring is the best time to observe hemlock trees. Check the underside of the branch for round white egg sacs near the base of the needles.

Up close, egg sacs look like tiny cotton balls and can appear singly or in clusters. A short video, “Hemlock Woolly Adelgid: An Invasive Species in Michigan,” provides helpful identification tips.

Report your findings

Report hemlock tree damage using the Midwest Invasive Species Information Network, available online at or as a downloadable smartphone app. When a report is made in the field, the MISIN smartphone app captures the GPS location. You can also upload photos along with your report.

Reports may also be submitted by email to or by calling the MDARD Customer Service Center at 800-292-3939.

Locate the infected tree and, if possible, take a photo or two of the infected branch to confirm identification. To avoid insect infestation, do not collect branches or twigs for samples.

manage trees

If you find hemlock woolly adelgid on your property, it is important to know that certain insecticides can treat the infestation if used correctly.

Without treatment, infected trees can die within 4 to 10 years. A qualified arborist, such as an International Arbor Society certified arborist, can diagnose infected trees and assist in treatment.

If you are able to treat it yourself, follow the guidance provided in the MSU Extension Information How to Treat Hemlock Trees for Hemlock Woolly Adelgid.

Even if you manage it yourself, reporting infected trees is important to determine how far hemlock woolly adelgid has spread. This information also indicates where additional investigation is required.

Find more information

For more information on identification, reporting, or treatment, visit the Michigan Invasive Species Program’s Hemlock Woolly Adelgid page at

Michigan’s invasive species program is implemented in collaboration with the Department of Environment, Great Lakes, and Energy. Department of Natural Resources. Ministry of Agriculture and Rural Development.

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