News Releases

December 10, 2012

Beetles Released to Control Spread of Hemlock Woolly Adelgid

Officials with the Vermont Department of Forests, Parks and Recreation announced that 379 Laricobius nigrinus beetles were released in Pownal on Thursday, December 6. The predatory beetles are part of a management strategy to control a tree-killing insect, the hemlock woolly adelgid. The adelgid is an invasive insect from Asia and threatens Vermontís hemlock trees. There are no significant natural enemies of hemlock woolly adelgid in Vermont. Laricobius beetles feed exclusively on adelgids and only complete development on a diet of hemlock woolly adelgid.

The beetles were raised in a lab at Virginia Tech, but are native to the Pacific Northwest. Hemlock woolly adelgid is native to the Pacific Northwest, but doesnít have a significant impact on tree health there, in part because of predation by the beetles. Laricobius nigrinus is the most studied of several beetles that have been approved by the USDA Animal and Plant Health and Inspection Service (APHIS) for use against hemlock woolly adelgid. Laricobius has been used as a biocontrol agent by the US Forest Service, US Fish and Wildlife Service, the National Park Service and several eastern states. APHIS issued a permit for the Pownal project. Since 2003, over 175,000 beetles have been released in 347 locations, including two others sites in Vermont. Monitoring of the Vermont sites has shown that the beetles are established.

The Pownal infestation was discovered this summer by a volunteer from the Forest Pest First Detector program. Foresters overseeing the project will continue to monitor the site for several years. They expect that the beetles will colonize the area and help to keep the hemlock woolly adelgid in check.

For more information on forest health issues, check the Vermont Department of Forests, Parks and Recreation web site at

Source: Department of Forests, Parks and Recreation
Last Updated at: December 10, 2012 11:33:06