E-mail: rturcotte@fs.fed.us
E-mail: dwanner@fs.fed.us

Forest Service Employees Monitor Colonization of
Beetles in Fight Against Hemlock Woolly Adelgid

Morgantown, WVa— David Mausel, a graduate student from Virginia Polytechnic Institute and State University, along with three USDA Forest Service State and Private Forestry officials from Morgantown, WVa, and Monongahela National Forest Silviculturist Glen Juergens Friday September 16 to conduct a survey for the predatory beetle Laricobius nigrinus in the Devil’s Garden area of the Marlinton Ranger District. About 300 beetles were released in the spring of 2004 as part of a study to see if they could become established and help control the hemlock woolly adelgid, an introduced pest.

This is the first of six samples that will be collected over the next 3 months to gather population information on the beetles. Because the beetles are so small—less than 3 millimeters in length—they are sampled by holding a white sheet under a hemlock branch and striking the branch to make the insects fall onto the sheet.

“We are sampling to determine if the beetles that were released last year have become established. If they become established, it becomes one more weapon in our arsenal against the adelgid. These preliminary studies will address some of the issues involved with using this beetle as a biological control agent,” said State and Private Forestry Entomologist Rick Turcotte. “There are currently only two methods to fight an infestation of adelgid. One is biological control, using beetles such as this one that are known to feed on adelgid, and the other is one of the chemical control methods,” said Turcotte.

The hemlock woolly adelgid is a nonnative pest that was first discovered in the Eastern United States in the 1950s. Adelgid populations began to increase dramatically and spread northward to New England in the 1970s. By the early 1990s, adelgid infestations began causing extensive hemlock tree mortality throughout the East. Heavy infestation of a hemlock tree can result in the tree’s death in 2 to 7 years. The hemlock woolly adelgid is easily identified by the white woolly material it produces on hemlock twigs.

The eastern hemlock is an important component of the forest. It does not have an ecological equivalent that can replace its role in the forest. It grows in dense stands, providing shelter when harsh weather conditions exist. The temperature can often be several degrees warmer inside these dense stands than in the surrounding forest on a winter night.