Hemlock Woolly Adelgid Has Gained a Foothold in Knox County


August 27, 2014

AUGUSTA, Maine – Hemlock woolly adelgid was recently recognized in Camden by a tourist who had battled the bug in his own backyard. It is clear the infestation in town is not limited to the two stately shade trees it was found on, but the question remains whether this insect has found its way into forests in and around Camden.

Hemlock woolly adelgid is a small, aphid-like insect. Most of the year, white, waxy tendrils cover the insect’s body, making it resemble a miniature cotton ball. It is most visible from late-October through July. The woolly masses can be found attached to hemlock twigs at the bases of needles. Although there are adelgids on other conifers, hemlock woolly adelgid is only found on hemlocks.

The insect, which came from Japan in the 1950s, causes premature needle drop and twig dieback, and can eventually lead to tree mortality. In Maine it has been found in forested areas from Kittery to Owls Head. Previously in 2014, the hemlock woolly adelgid had been found in forested areas of Friendship and Owls Head in Knox County during Maine Forest Service detection surveys. If a broader infestation is found in Camden, the city will be the third municipality in the County and the 43rd in the state with a known established population in forest trees.

Hemlock trees are a significant Maine tree species. Often found near lakes and streams, hemlocks contribute to Maine’s water quality. They also buffer stream temperatures which can affect such species as brook trout. The trees, which are a favored landscape tree, are also important in deer wintering areas and contribute to the state’s forest economy.

In some Maine communities with hemlock woolly adelgid, populations of the insect are scattered and hard to find. In others, it can seem harder to find hemlocks free from adelgid than those with it. In the latter areas, pockets of noticeable adelgid-related decline are becoming apparent. For the first time this year, adelgid-related hemlock mortality has been noted during aerial survey.

The Maine Forest Service asks that people take some time to check their hemlocks for signs of this pest. And, if you think you’ve seen it, please report it. Public participation in detecting and reporting this insect allows us to more wisely apply resources for management of the pest. Information on distribution helps Maine Forest Service target surveys and management activities such as release of predator beetles.

If you think you have found evidence of hemlock woolly adelgid in Maine please call or email the Maine Forest Service at: (207) 287-3147 or forestinfo@maine.gov For more information hemlock woolly adelgid, please see: http://www.maine.gov/dacf/mfs/forest_health/insects/hemlock_woolly_adelgid.htm