Maryland Reaches New Milestone in Biocontrol Efforts for Eastern Hemlock Conservation

ANNAPOLIS, MD – This fall, the Maryland Department of Agriculture’s Forest Pest Management Program achieved a significant milestone in protecting Eastern Hemlock trees through its ongoing partnership with state and federal agencies, utilizing the Laricobius nigrinus beetle as a control method.

From October 25 to November 18, 2024, the Forest Pest Management team conducted inter-state collections of L. nigrinus beetles at Rocky Gap State Park. These beetles, first released in 2004 as part of a strategic pest management initiative, have played a crucial role in combatting the invasive hemlock woolly adelgid, a serious threat to the health of Eastern Hemlocks. Thanks to the collaborative efforts between the department and the U.S. Forest Service’s Hemlock Woolly Adelgid Initiative, Rocky Gap State Park has emerged as one of the most successful locations on the East Coast for the establishment of this biological control.

This year’s collection set a new state record, with over 14,000 L. nigrinus beetles harvested and redistributed to various states including Vermont, Kentucky, Tennessee, and multiple sites within Maryland. Over the past four years, this multi-state cooperative project has successfully collected more than 33,000 beetles, aiding vulnerable hemlock forests as far north as Maine and as far south as Tennessee.

The success of this initiative can be attributed to the dedicated efforts of Forest Pest Management staff, particularly former Forest Health Specialist Biff Thompson. His two decades of expertise in establishing L. nigrinus populations in Maryland and his commitment to training staff in beetle behavior and collection techniques have been instrumental. Thanks to his leadership, staff were able not only to collect thousands of beetles from Rocky Gap but also to identify four new sites across Maryland with high potential for future collections.

Participants in the 2024 project also included the Maryland Department of Natural Resources, Catoctin Mountain Park, Kentucky Division of Forestry, The Nature Conservancy, Tennessee Department of Agriculture Division of Forestry, Vermont Agency of Natural Resources, and the U.S. Forest Service. The success of this initiative demonstrates the power of collaboration among these state and federal organizations.

For more information about the department’s Eastern Hemlock Conservation program please visit www.mda.maryland.gov.