Biological Control Release Underway Bolsters Second Round of Treatment to Limit Spread of Invasive, Tree-Killing Pest
The New York State Department of Environmental Conservation (DEC) and partners announced that additional efforts to limit the spread of the invasive hemlock woolly adelgid (HWA) on Forest Preserve lands in Washington County are underway. DEC forestry staff are treating 29 acres of infested hemlock stands near Shelving Rock and additional infested hemlocks near Paradise Bay. DEC is partnering with the New York State Hemlock Initiative and Cornell University to release Leucopis silver flies, a biological control for HWA, near Paradise Bay. These efforts are part of an ongoing, multi-year initiative to control the HWA infestation along the shores of Lake George that was discovered last August. Additional partners in these treatment efforts include the Adirondack Park Invasive Plant Program (APIPP) and Lake George Land Conservancy (LGLC).
“Hemlocks are the fourth most common tree in New York’s forests and their ability to grow on steep slopes along streams makes these trees fundamental in terms of preventing erosion, filtering pollutants from runoff, and maintaining cold-water habitat,” said DEC Commissioner Basil Seggos. “Preventing the spread of these hemlock-killing pests is essential for protecting the vital ecosystem services that hemlock forests provide for the Lake George Watershed and the greater Adirondack Park.”
DEC crews are using bark applications of the chemicals imidacloprid and dinotefuran to treat infested hemlock. However, direct injections are used for ecologically sensitive areas and when wet weather conditions interfere with bark applications. Before treatment, crews conduct surveys to identify and mark trees to be treated. This process helps to ensure treatments are applied to the trees that need it most. The flagging is removed once the tree is treated and tags are left at the base to identify treated trees. These flags should not be removed or disturbed by anyone other than the staff working to treat the trees. A photo of the tags is attached.
In addition, DEC and partners are releasing Leucopis silver flies collected in the Pacific Northwest for the Hemlock Woolly Adelgid Biocontrol Research Lab at Cornell University to be prepped for release. These are predatory flies that feed on HWA eggs laid in the spring and the release of the Leucopis silver flies complements the October 2020 release of Laricobius beetles, another biocontrol that feeds on developing and adult HWA during the fall and winter. The goal of these deployments of predatory insects is to establish stable populations in the area and provide long-term, year-round protection for the region’s hemlock forests.
“DEC and partners have done an admirable job responding to the spot infestations on Lake George to slow the spread of HWA,” said Mark Whitmore, Director of the New York State Hemlock Initiative based at Cornell University. “The use of insecticides will give us time necessary to implement classic biological control with predators from the Pacific Northwest where HWA is a native insect. The three predator species we are releasing feed exclusively on adelgids and are known to effectively control HWA in the west.”
About Hemlock Wooly Adelgid
A tiny insect from East Asia, HWA feed on young twigs, causing branch dieback as needles dry out and drop prematurely. Hemlock decline and mortality typically occurs within four to 10 years of the initial HWA infestation.
Signs of HWA include:
- white, woolly masses (ovisacs) about one-quarter the size of a cotton swab and found on the underside of branches at the base of needles;
- gray-tinted foliage; and
- significant needle loss and branch dieback.
HWA is mobile for only a short period of time in the spring from mid-April through mid-June. DEC is asking anyone surveying for HWA or entering a hemlock stand for any reason to clean off any equipment or gear used and to leave infested branches where they are found. If a suspected infestation is found, please:
- Take pictures of the infestation signs as described above, include something for scale such as a coin;
- Note the location, including intersecting roads, landmarks, or GPS coordinates; and
- Email the information to DEC at [email protected], contact the local Partnership for Regional Invasive Species Management (PRISM, available at DEC’s website for contact info), or report the infestation to iMapInvasives.
To support New York State’s overall efforts to combat invasive species, the State Budget once again earmarked $13.3 million from the Environmental Protection Fund to support prevention and control activities. This sustained funding continues to provide critical support for prevention, eradication, research, and biological control efforts through programs like the New York State Hemlock Initiative and through the PRISM network, which protects against threats to New York’s biodiversity, economy, and human health at the local level.
For more information on HWA, including identification, control techniques, and reporting possible infestations, visit DEC’s website. For more information on the NYS Hemlock Initiative, visit Cornell University’s website. Report possible infestations to [email protected] or call DEC’s toll-free Forest Pest Information Line at 1-866-640-0652.
Hemlock woolly adelgid (pictured above), emerald ash borer, and spotted lanternfly are three bad bugs that will be highlighted during the Forest Pest Symposium on April 22. Photo by Michael Montgomery, USDA Forest Service, Bugwood.org.