Department of Natural Resources
Nov. 18, 2020
Crews have treated affected trees and continue to survey the area
The Michigan Department of Natural Resources recently confirmed a new detection of invasive hemlock woolly adelgid at Ludington State Park in Mason County. On Oct. 19, 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.
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.
|“It was a cold, clear morning, and I had just completed a careful binocular survey of a large tree. I turned around to another, smaller hemlock and saw the ovisac right away,” said Wilcox. “We spend a lot of time looking at these trees. Anything white on the underside of a branch catches our attention.”
Due to its experience, the crew at Ludington was able to survey the surrounding area quickly and treat nearly 400 hemlocks in the vicinity to try to prevent the infestation from spreading or intensifying. Through survey efforts, four additional infested trees were identified.
|Ludington State Park is the eighth state park where hemlock woolly adelgid populations have been found, and currently the northernmost point of infestation. Eastern hemlock trees are an integral part of Michigan’s coastal dune ecosystem, which stretches along the state’s west coast into the U.P. Hemlocks are also found in Michigan’s northern hardwood forests.
Hemlock woolly adelgids can be carried to new locations, sometimes miles away, by birds, wildlife and even wind. This new detection so far away from other known infestations highlights the importance of regular surveillance of hemlock trees.
Residents with hemlock trees on their properties and anyone visiting forested areas this winter can assist in this effort by taking time to look at the undersides of hemlock branches for evidence of hemlock woolly adelgids. Birders with binoculars can be especially helpful in spotting the invasive pest.
|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.
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 Michigan.gov/HWA. Help in identifying eastern hemlock trees is also available at the same site.
Trees infested with HWA should be reported by one of the following means:
Be prepared to report the location of infested trees and, whenever possible, take one or two pictures of infested branches to help confirm identification. To avoid spreading hemlock woolly adelgid, do not collect sample branches or twigs.
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.
The Michigan Civilian Conservation Corps is a career training program geared toward those who want to learn what it's like to work in the natural resources field. The DNR’s MCCC Forest Health crew is partially funded by the Great Lakes Restoration Initiative and Michigan Invasive Species Grant Program and works in partnership with AmeriCorps.
MCCC staff are full time State of Michigan employees and are eligible to sign up for AmeriCorps service awards which can be used for educational expenses or repayment of qualifying student loans. More information about the MCCC/AmeriCorps program is available at Michigan.gov/DNRJobs.
Michigan's Invasive Species Program is cooperatively implemented by the Department of Environment, Great Lakes, and Energy, the Department of Natural Resources, and the Department of Agriculture and Rural Development.
Note to editors: Accompanying photos are available below for download. Suggested captions and photo credit information follow:
Magnification: Round, white hemlock woolly adelgid ovisacs are found on the undersides of branches near the base of the needles. Photo courtesy of Lorraine Graney, Bartlett Tree Experts, Bugwood.org
Ovisac: The tiny white spot on the center of this branch is the hemlock woolly adelgid ovisac spotted by MCCC crew member Travis Wilcox during a survey at Ludington State Park.
Mason map: Map showing the known infestations of hemlock woolly adelgid in Mason County, including Ludington State Park.
Hemlock tree: Hemlock trees are generally cone-shaped with lacy or feathery branches.