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Michigan Department Of Natural Resources Says Tiny, Invasive Insects From Asia Found In Michigan State Park

(CBS DETROIT) - The Michigan Department of Natural Resources recently confirmed a new detection of invasive hemlock woolly adelgid at Ludington State Park in Mason County.

It happened on Oct. 19, where DNR says a single hemlock woolly adelgid adult and ovisac were found on a hemlock tree branch in a wooded area off a trail near the west shore of Hamlin Lake.

Hemlock woolly adelgids are tiny insects from Asia that feed on the sap of hemlock trees, spinning white, waxy ovisacs to protect their eggs.

Over time, their feeding kills needles, branches and whole trees.

These insects are considered invasive because they are not native and can cause significant harm to Michigan's hemlock resource, estimated at 170 million trees.

This discovery is approximately 17 miles north of Bass Lake, where the first hemlock woolly adelgid infestation in Mason County was detected in March 2020, prompting the Michigan Department of Agriculture and Rural Development to extend its hemlock woolly adelgid internal quarantine in September.

The internal quarantine, which regulates movement of hemlock nursery stock, forest products and yard waste, now covers Allegan, Ottawa, Muskegon, Oceana and Mason counties, all bordering Lake Michigan.

The single insect and ovisac were spotted by Travis Wilcox, a member of the Michigan Civilian Conservation Corps Forest Health Crew in the DNR's Parks and Recreation Division, during a routine survey of the park's hemlock forests.

What to look for

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 balls of spun cotton and may appear alone or in clusters. The short video Hemlock Woolly Adelgid: Invasive Species in Michigan provides helpful identification tips.

Other, less damaging pests easily can be mistaken for hemlock woolly adelgids. Be sure to review photos and descriptions of common hemlock woolly adelgid look-alikes at Help in identifying eastern hemlock trees is also available at the same site.

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