LANSING, Mich. — For the first time in the history of the infestation in Michigan, Hemlock woolly adelgid (HWA) has been found in non-landscape and non-nursery settings.

HWA, a native of Asia, is a small, aphid-like insect that threatens eastern hemlock and Carolina hemlock in the eastern United States. HWA is a small, sap-feeding insect that always nestles in the needles of the tree.

The Michigan Department of Agriculture and Rural Development (MDARD) has been monitoring for HWA since 2001, however, until this year infestations found here were restricted to nurseries and hemlock landscaping. Different kinds of hemlock are often used as bushes in landscape settings to achieve different kinds of aesthetic effects, said John Bedford, pest response program specialist at MDARD.

Hemlock bushes are considered important for wildlife habitat and for providing shade for the state’s trout streams.

The latest discovery of HWA was found in a semi-wild setting, although it’s possible hemlock was planted in this area, Bedford stated. Since HWA had probably been in this area for the better part of a decade – it was found in Muskegon County in southwestern lower Michigan – it’s impossible to know for certain exactly how HWA got to that specific site. Officials do know that all HWA was brought to Michigan from nursery stock outside the state at some point.

"Once again, citizen involvement played a central role in early detection," said Gina Alessandri, MDARD’s pesticide and plant pest management division director in an MDARD press release September 16. "Examine your hemlock for HWA and if you find something suspicious contact MDARD immediately."

HWA is characterized by white, woolly masses that appear on the stems of hemlock during its development. Last June, an Ottawa County based arborist found HWA in Park Township. He reported his finding to MDARD, which had the USDA test samples to provide confirmation of the pest. MDARD then conducted a survey of trees in a one-mile radius and discovered two more positive locations for HWA.

Each infestation was treated, eradication activity took place and continual survey occurred after eradication activities had wrapped up.

"It’s a little bit different this time because this was found in a more forested setting. Some landscape plants may have been put in there, but a lot of times this is difficult if not impossible to prove," Bedford said.

Although HWA is not especially fast-moving, the insects do cause tree decline and death, usually within 4-10 years of infestation in the insect’s northern range. The invasive pest was first reported in the United States in 1951 near Richmond, Va.