Forest
Stewardship News Release
January
27, 2004 - For Immediate Release
Contact: Rance
Harmon, Phone: 814-863-0401 E-mail: rsh144@psu.edu
Exotic Pests Feed on Pennsylvania State Tree
Eastern hemlock, an attractive evergreen tree with small, flat needles, is a favorite among Pennsylvanians but also a favorite of many insect and arachnid pests: the elongate hemlock scale, spider mite, hemlock rust mite, hemlock borer, hemlock looper, and the now infamous—hemlock woolly adelgid. If you live anywhere in Pennsylvania, except the westernmost part of the state, now is the time to check your hemlocks for the infestation of this soft-bodied aphid relative. According to Shahla Werner, DCNR Forest Entomologist, the hemlock woolly adelgid’s egg sacs are especially visible in the wintertime.
Originally from Japan, the hemlock woolly adelgid has traveled throughout the Eastern United States by way of wind, and by “hitchhiking” on birds, plants, mammals and humans. In the 35 years since it was first discovered in Pennsylvania, the hemlock woolly adelgid has spread to 43 counties, north to Bradford, south to Somerset, and as far west as Allegheny. Look for discolored, gray-green needles with white, woolly sacs on the underside. Hemlock woolly adelgid sucks the sap from the tree causing a loss of foliage and eventually leads to branch and tree mortality.
To help stop the spread of the hemlock woolly adelgid and other exotic pests such as the elongate hemlock scale, Werner encourages landowners to clip heavily infested branches, dispose of them by burning, and to avoid moving foliage around. Placing a bird feeder in a hemlock stand could also aggravate the spread.
In some areas of Pennsylvania the elongate hemlock scale is of greater concern than the hemlock woolly adelgid. “There are some sites, particularly in Lycoming County, where there’s virtually no hemlock woolly adelgid, but lots of elongate hemlock scale,” says Werner. Trees infested with elongate scale will have yellow needles with waxy coverings on the underside that protect the insect while it feeds.
Last year, the Department of Conservation and Natural Resources (DCNR) Forest Pest Management (FPM) Division began releasing a specialized beetle species that feeds on the elongate hemlock scale. For the past four years, FPM has also released a specialized beetle that feeds on the hemlock woolly adelgid. Since this beetle predator lies dormant in the winter while the hemlock woolly adelgid proliferates, FPM is currently assisting Virginia Polytechnic Institute in their research to find a beetle that will eat the winter generation of this exotic pest. So far, 300 of the new beetles have been released. Werner estimates that it could take another ten years before the three beetles species provide a permanent source of control.
FPM does not recommend beetles for commercial use. “If you own hundreds of acres of hemlocks it might be appropriate,” says Werner. “But for localized woodlots it’s too expensive and the beetles do tend to migrate. Because the hemlock woolly adelgids are so prolific you’d really need a lot of beetles to control them.”
To learn more about hemlock pests, visit the DCNR Forest Pest Management site or request a free fact sheet on the hemlock woolly adelgid from FPM, 717-948-3941, The Penn State Cooperative Extension also has a fact sheet about hemlock woolly adelgid.
The Pennsylvania Forest Stewardship Program provides publications on a variety of topics related to woodland management for private landowners. For a list of free publications, call 1-800-235-WISE (toll-free), send e-mail to RNRext@psu.edu, or write to: Forest Stewardship Program, Forest Resources Extension, The Pennsylvania State University, 320 Forest Resources Building, University Park, PA 16802. The Pennsylvania Bureau of Forestry and USDA Forest Service, in partnership with the Penn State's Forest Resources Extension, sponsor the Forest Stewardship Program in Pennsylvania.
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