File photo by Michigan Department of Natural Resources

The Michigan departments of Natural Resources (DNR) and Agriculture and Rural Development (MDARD) encourage Michigan residents who have eastern hemlock trees on their property to take time this winter to inspect the trees for signs of hemlock woolly adelgid (HWA).

HWA are tiny, soft-bodied insects that consume the trees’ stored nutrients, according to a DNR press release on Nov. 20. The DNR states that 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 in the release. “As the 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.”

The DNR states that 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 HWA have been confirmed in Allegan, Antrim, Benzie, Leelanau, Manistee, Mason, Muskegon, Oceana, Ottawa, Van Buren, and Washtenaw counties.

Winter surveys underway

According to the DNR, throughout the winter, survey crews from the DNR and multiple cooperative invasive species management areas, or CISMAs, will look for signs of HWA. Crews will focus their efforts along the northern edge of the infestation, conducting surveys within a 5-mile border along the Lake Michigan shoreline.

The release states that because hemlock trees can be protected from these insects with proper insecticide treatments, infested trees and any other hemlocks within the area will be mapped and tagged, then prioritized for summer treatment.

If designated survey areas include private lands, CISMAs first will seek landowner permission, according to the DNR. CISMA survey efforts are supported by funds from the Michigan Invasive Species Grant Program and the U.S. Forest Service and are provided at no cost to these landowners.

Your help is needed

The DNR states that though dozens of staff will assist in the surveys, they won’t be able to check every hemlock. If Michigan residents have hemlocks on their property, whether it’s within or beyond the 5-mile shoreline border, the DNR suggests taking some time to look for signs of HWA.

The DNR states that in Michigan’s northern forests, hemlock trees are found in moist soils along streams and riverbanks and along coastal dunes. Hemlock also is popular as a landscape tree in parks and residential areas.

Identify hemlock trees

Since these 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, according to the release. Michigan residents should look for the following.

— 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.

Look for signs

The DNR states that late fall through early spring is the best time to check hemlock trees. Those checking the trees should look on the undersides of branches for evidence of round, white ovisacs near the base of the needles.

Report your findings

Individuals should report infested hemlock trees by using the Midwest Invasive Species Information Network, available online misin.msu.edu/, according to the DNR. 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.

Those reporting infested hemlock trees should identify the location of infested trees and, whenever possible, take one or two pictures of infested branches to help confirm identification, according to the release. To avoid spreading the insect, the DNR encourages people to not collect sample branches or twigs.