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Home > Bugs > Bugs of Trees and Shrubs > Hemlock Woolly Adelgid

Hemlock Woolly Adelgid—Adelges tsugae

Hemlock woolly adelgid (HWA) is a serious pest of eastern hemlock. Feeding from HWA causes needles to discolor and drop prematurely. Tree death can occur within a few years from the first infestation. HWA is dispersed by wind, birds, mammals and can be moved on plants in the nursery trade.

A Hemlock Woolly Adelgid Quarantine was established to protect Maine's hemlocks. Despite the best efforts to prevent the spread of HWA in Maine, several towns are known to be infested (map). A quarantine remains in place to slow and prevent the spread of HWA into other parts of the state.

 

hemlock with hemlock woolly adelgid needles with hemlock woolly adelgid close-up of hemlock woolly adelgid
The most obvious sign of HWA infestation are the white cottony masses, resembling cotton balls, found at the base of the hemlock needles.

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Identification and Control Information (each will open in a new window)

More Information (each will open in a new window)

 

[Photos, left to right: James Johnson, Georgia Forestry Commission, Bugwood.org; Connecticut Agricultural Experiment Station Archive, Connecticut Agricultural Experiment Station, Bugwood.org; Chris Evans, River to River CWMA, Bugwood.org]

 
It is the policy of the State of Maine to minimize reliance on pesticides. The Maine Department of Agriculture and the Maine IPM Council encourage everyone to practice integrated pest management and to use pesticides only as a last resort. The mention of pesticides in the fact sheets linked to these pages does not imply an endorsement of any product. Be sure that any product used is currently registered and follow all label directions.