Lake George

A small cluster of early-stage hemlock woolly adelgid has been found in the Forest Preserve.

The state Department of Environmental Conservation confirmed on Tuesday the presence of Adelges tsugae, a small, aphid-like insect that threatens the health of eastern hemlock. The first known infestation of the invasive insect in the Adirondacks was found on an old-growth Eastern hemlock tree on Prospect Mountain.

Hikers, campers, boaters, sportsmen and others using forests or surrounding areas in northern Schenectady, Saratoga and southern Warren counties are asked to check Eastern Hemlock trees and report any HWA infestations.

The cluster was found during a field trip by a senior ecologist from Harvard Research Forest. The DEC sent a HWA survey crew to the site and was joined by staff from Cornell University’s New York State Hemlock Initiative. HWA was confirmed on a number of branches on the tree by a Cornell scientist and later by DEC’s Diagnostic Lab. The mature tree had no visible sign of crown thinning.

The crews spent 72 person hours surveying 250 acres of forest and found only one other tree, a small eastern hemlock near the original infested tree, that contained one branch with a small cluster of early stage HWA.

Previously, it has been detected in 29 other counties in New York, primarily in the lower Hudson Valley and, more recently, in the Finger Lakes region.

Seventeen other states along the Appalachian Mountain range from Maine to Georgia also have HWA infestations.

The DEC is evaluating ways to eradicate this infestation and prevent it from spreading. The most effective treatment method for control is an insecticide applied to the bark near the base of the tree and absorbed and spread through the tissue. When HWA attaches itself to tree to feed, it receives a dose of the pesticide and is killed.

HWA, a tiny insect from East Asia first discovered in New York in 1985, attacks forest and ornamental hemlock trees. It feeds on young twigs, causing needles to dry out and drop prematurely and causing branch to die. Hemlock decline and mortality typically occur within four to 10 years of infestation in the insect’s northern range.

Eastern hemlocks are among the oldest trees in New York with some reaching more than 700 years in age. They typically occupy steep, shaded, north-facing slopes and stream banks where few other trees are successful.