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Archive for the hemlock woolly adelgid tag

Invasive Hemlock Woolly Adelgid Pest Found at More Sites in West Michigan

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The public is asked for continued help in looking for invasive pests

The small cottony masses characteristic of adult hemlock woolly adelgid. (Credit: Connecticut Agricultural Experiment Station Archive)
The small cottony masses characteristic of adult hemlock woolly adelgid. (Credit: Connecticut Agricultural Experiment Station Archive)

Thanks to an alert citizen working in the area, the Michigan Department of Agriculture and Rural Development (MDARD) today confirmed hemlock woolly adelgid (HWA), an invasive tree-killing pest discovered in Ottawa County in June, has now been found at locations in southwestern Muskegon County. The finds in Ottawa and Muskegon counties are the first instances of HWA occurring in native forest hemlock.

MDARD and its partners have been actively monitoring and controlling HWA since 2001, but until this year, all HWA infestations found in Michigan were restricted to nurseries and hemlock landscaping. Each infestation was treated, eradication activity took place, and continued surveillance occurred after eradication activities were wrapped up.

“Once again, citizen involvement played a central role in early detection. Continued citizen involvement and citizen reporting is crucial for the management of this pest or any other exotic pest,” said Gina Alessandri, MDARD’s Pesticide and Plant Pest Management Division Director. “Examine your hemlock for HWA, and if you find something suspicious, contact MDARD immediately.”

Hemlock trees are typically green in color, but in advanced HWA infestations, twig and branch mortality can occur, giving infested trees a grayish hue. The small cottony masses characteristic of HWA are found on the underside of the branch at the base of the needle; they are never found on the needles themselves.
HWA can be very difficult to detect at low population levels because the insect is so small.

Since its discovery in Virginia in 1951, HWA has spread rapidly across most of the native range of hemlock in the eastern U.S., decimating hemlock forests from Georgia to Maine. To protect Michigan’s hemlock forests and the wildlife they support, MDARD has maintained a strict quarantine against out-of-state hemlock since 2002. Current and past infestations in Michigan are likely the result of hemlock from these areas shipped into Michigan prior to, or in violation of, this quarantine.

To report a possible HWA detection, contact MDARD at 800-292-3939 or MDA-info@michigan.gov.

Hemlock Woolly Adelgid Eradicated from Three Michigan Counties

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hemlock-woolly-adelgidAccording to the Michigan Department of Agriculture and Rural Development, Hemlock Woolly Adelgid (HWA) has been eradicated from three counties across the state: two sites in Macomb County, two sites in Ottawa County, and multiple locations within Emmet County. HWA was first detected in Emmet County in 2006, then at the Macomb and Ottawa county sites in 2010.

The infestations were believed to have originated from hemlock nursery stock originating from HWA-infested areas of the U.S. The infested trees at each site were removed and destroyed. Nearby trees were treated with pesticides and surveyed annually over the course of at least three years.

HWA is a small, aphid-like insect that uses its long, siphoning mouthparts to extract sap from hemlock trees. Native to eastern Asia, HWA was discovered in Virginia in 1951, and has since spread over an area from Georgia to Maine, decimating hemlock stands.

Over 100 million hemlock trees are present in Michigan forests, providing valuable habitat for a diversity of animals, including birds, deer, and fish. These trees are critical to the ecology and aesthetics of Michigan’s northern forests. Michigan law restricts the movement of hemlock into the state, and includes a complete ban on the movement of hemlock from infested areas.

Tree owners are asked to examine their hemlocks for the presence of white, cottony masses on the underside of branches where the needles attach. If you suspect HWA, contact MDARD immediately: email MDA-Info@michigan.gov or call 800-292-3939.

For more information on the HWA quarantine or other exotic pests, go to www.michigan.gov/exoticpests.

Michigan’s Hemlock Trees Face Big Threat from a Tiny Insect

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Michigan Department of Agriculture recommends inspecting your hemlock trees

The hemlock woolly adelgid (HWA) is a tiny, aphid–like insect that damages hemlock trees by inserting its mouthparts into the base of the needles and removing plant fluids.
The hemlock woolly adelgid (HWA) is a tiny, aphid–like insect that damages hemlock trees by inserting its mouthparts into the base of the needles and removing plant fluids.

The Michigan Department of Agriculture & Rural Development (MDARD) is reminding homeowners and landscapers that although hemlock woolly adelgid (HWA) can be seen year round, spring is one of the better times to inspect hemlocks for their presence.

“The HWA is a tiny, aphid–like insect that damages hemlock trees by inserting its mouthparts into the base of the needles and removing plant fluids,” said Gina Alessandri, director of MDARD’s Pesticide and Plant Pest Management Division. “This feeding activity results in needle loss, reduced twig growth, dieback and death. HWA can kill an entire tree in as few as three years.”

HWA was first discovered in Virginia in 1951 and has since infested hemlock trees from Maine to Georgia. HWA has decimated hemlock stands across much of the eastern U.S.

Approximately 100 million hemlock trees are present in Michigan forests and hemlocks are commonly utilized in landscape plantings. At this time, HWA is not known to exist in Michigan although it has been found here before.  HWA has been documented in the Harbor Springs/Petoskey area (2006, 2007, and 2010), the Utica and Clinton Township areas of Macomb County (2010), the Grand Haven and Holland areas (2010) and the New Buffalo area of Berrien County (2012). At each of these sites, MDARD required the removal and destruction of infested trees, treated hemlocks in close proximity to those infested trees with insecticides and is conducting follow-up surveys.

The biggest threat of introduction of HWA into Michigan comes from the importation of hemlocks, primarily through the nursery and landscape trade, from areas where HWA is established.  If you have ever had hemlock planted on your property, your hemlocks could have an increased risk of having HWA. Michigan’s Hemlock Woolly Adelgid Quarantine restricts the movement of hemlock into the state, and includes a complete ban on the movement of hemlock from infested areas of the country into Michigan.

Examine your hemlocks for the presence of white cottony masses on the underside of the outermost branch tips where the needles attach. As it matures, HWA produces a covering of cottony-like wax filaments to protect itself and its eggs from natural enemies and to prevent them from drying out. The “cotton” can be readily observed from late fall to early summer.

“Most positive reports of HWA in Michigan have come from alert and conscientious arborists and landscapers,” said Alessandri.  “This underscores the importance of citizen involvement in invasive pest detection.”

If you suspect you have seen HWA, immediately call MDARD’s Customer Service Center at (800) 292-3939 or via email at MDA-Info@michigan.gov and report it.”

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