Forest Health: Hemlock Woolly Adelgid

The Hemlock Woolly Adelgid moved into Kentucky in 2007 and has been found on the Daniel Boone National Forest.

Hemlock forests in the neighboring states of Tennessee and Virginia are dying from attacks by the hemlock woolly adelgid (Adelges tsugae), a non-native invasive insect. Agency personnel and other forest health experts are researching options for the control of this insect on the Daniel Boone National Forest.

The hemlock woolly adelgid has been in the United States since 1924. This introduced insect, believed to be a native of Asia, is a serious pest of eastern hemlock and Carolina hemlock. In the eastern United States, it is present from the Smoky Mountains north to the mid-Hudson River Valley and southern New England.

White cottony sacs at the base of hemlock needles are good evidence of hemlock woolly adelgid infestation. These sacs resemble the tips of cotton swabs. They are present throughout the year but most prominent in early spring. (Scroll down to see photos below.)

The hemlock woolly adelgid feeds during all seasons with the greatest damage occurring in the spring. It is dispersed by wind, birds and mammals.

By sucking sap from the young twigs, the insect retards or prevents tree growth and causing needles to discolor from deep green to grayish green and to drop prematurely. The loss of new shoots and needles seriously impairs tree health. Defoliation and tree death can occur within several years.

Links:

http://www.na.fs.fed.us/fhp/hwa/

http://www.invasivespeciesinfo.gov/animals/hwa.shtml

http://www.saveourhemlocks.org/

http://www.invasive.org/hwa/

Below are photos of hemlock woolly adelgid infestations. More images available at Forestry Images.

 

Insect Threats

Chestnut Borer | Gypsy Moth | Southern Pine Beetle | Sudden Oak Death

Other Forest Health Topics

Four Threats to Forest Health | Forest Health Initiative | Red cockaded woodpecker | Invasive Species | Prescribed Burning

Title: Hemlock Woolly Aldegid
Last Updated: July 27, 2009