Hemlock Woolly Adelgid

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woollyadelgidSummer 2014 Update

On Monday, July 14, 2014 all 235 Eastern Hemlock trees located at Hemlock Bluffs Nature Preserve in Cary were treated with Safari using the bark painting method of application by Bartlett Tree Experts. The process took about five hours and expectations are high for complete success in eradicating the pest. After the 2010 treatment, adelgids were not found for over four years, and similar results should are expected with this treatment. The Town of Cary, working with experts in the field of entomology and engaging Bartlett Tree Experts, has taken swift action to protect these important trees at Hemlock Bluffs Nature Preserve. Moving forward, continued inspections will occur twice annually.

Adelgids Return to Hemlock Bluffs

During the routine physical inspection of the hemlock trees by a third party company in June 2014, Hemlock Woolly Adelgids were found present on at least one tree in the Nature Preserve. A management plan is in place to suppress and eliminate Hemlock Woolly Adelgids.

To treat for the Hemlock Woolly Adelgid, contractors will apply treatment to the bark of all 235 Eastern Hemlock trees at Hemlock Bluffs. The treatment dries quickly and is completely absorbed by the bark, thus preventing any broader impact on surrounding plants, wildlife, and soils. The solution remains effective for at least two years, killing adelgids as they feed. The method of painting bark is the least invasive method of eradicating adelgids, and was determined to be the most appropriate treatment for the adelgids at Hemlock Bluffs Nature Preserve. This same treatment was used on all of the Eastern Hemlock trees in August 2010. There were no signs of the Hemlock Woolly Adelgid following the 2010 treatment until the June 2014 inspection.

Due to predicted weather, bark painting is now planned for July 14. Stevens Nature Center and Hemlock Bluffs Nature Preserve will remain open during the treatment application.


The Hemlock Woolly Adelgid (Adelges tsugae) is a tiny, non-native aphid-like insect that, if left unchecked, kills hemlock trees by feeding at the base of hemlock needles and preventing nutrients from flowing to the needles - the needles drop, and the tree dies. Scientists believe Woolly Adelgids can kill Hemlocks within a matter of years.

Knowing that the insects devastated hemlock populations throughout the eastern United States, the Town of Cary worked with area experts to develop the Hemlock Woolly Adelgid Treatment Plan used in 2010. The treatment was successful, lasting twice as long as estimated. The same plan will be implemented again due to its effectiveness.

More Information

The Preserve is a partnership between the Town of Cary – which maintains the Preserve, operates the programs, and owns the structures -- and the State of North Carolina, which owns most of the land and helps guide its stewardship. Citizens with questions on maintaining hemlock trees on private property can contact Stevens Nature Center or email questions to hemlocks@townofcary.org.


Brochure: Hemlock Woolly Adelgid - NC Division of Forest Resources


Mark Johns
Operations and Program Supervisor- Environmental

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