Hemlock Wooly Adelgid Monitoring Program

About Hemlocks

The eastern hemlock, Tsuga canadensis, is an important species of tree to the ecosystem of northern New York. This species helps stabilize soils and streambanks preventing erosion, shades those same streams to keep the water cool for trout and provides habitat for the mammals and birds that live in the area.   

Forest Pest Alert!

Hemlock Wooly Adelgid (HWA) is a forest pest from Japan that made its way to the East Coast in 1951. Since its introduction into the U.S., HWA has spread across the eastern seaboard where hemlock trees are very present. This parasite caused massive damage to native hemlock stands in the Carolinas and other mid-coast states. In 2017, the first detected site of infected hemlock trees with HWA was found in the town of Lake George.

What Can You Do?

The good news is you can help make a difference in preventing the spread of Hemlock Wooly Adelgid! By informing yourself and fellow citizens of what to look for and reporting any findings to the DEC you can help them contain the insect. The best time to look for them is between late fall and early summer, when the white, wool-like filaments are visible on the undersides of the needles, growing near the point that the needle attaches to the stem. While less visible, one can also look for the insect itself, which present on the tree at the base of the needles as a one and a half mm long purple-black mass. Landowners have an opportunity to join our monitoring program to help us share information with other organizations about new infestations. The District can also assists landowners with planning their plantings and provide information on the identification, management options, monitoring for HWA, and what to look for as signs of infection on the hemlocks that they do have.

Wooly egg masses on the underside of the needle are a common sign of HWA

Tamarack Trees (Larix laricina)

Known properly as the Eastern Larch, this is a tree that is native to New York and is often found co-habituating with the eastern hemlocks that we are trying to conserve. These trees are a deciduous conifer that will lose their needles every winter, this makes for some spectacular fall foliage as the needles turn a brilliant gold color in the fall every year.

They are not seen as palatable by deer and generally are not browsed on, which can be advantageous if the landowner wishes to avoid. They do best in wet soils, but are tolerant to most soil types that are not extremely dry, doing well in acidic and oxygen deficient soils. They prefer partial shade, allowing the landowner to plant them in areas that are unsuitable for other trees.

Need planting guidance? Request a site visit: District staff will work with landowners to provide technical assistance on where to plant their new seedlings and offer one on one assistance identification, management options, and monitoring for HWA. If you have any questions for us regarding this program, please feel free to contact Jake Dunkley at jaked@warrenswcd.org!

Key Features for Identifying Hemlock Trees

While the eastern hemlock looks like other trees native to the area it can be distinguished easily by looking at the structure and attachment of the needles. 

  • Hemlock needles are soft and flat, with rounded tips, they connect to the tree with a fine wood-like attachment point. Hemlocks differ from spruce trees which have a hard needle that feels square when rolled between one’s fingers. 
  • Balsam and other fir trees can be differentiated by looking at the way in which the needles attach to the stem.  In contrast to the fine attachment points characteristic of the hemlock, fir trees have suction cup-like protuberances at the base of their needles.  In addition, there will be two white lines along the bottom of the needle which give a good visual indication of the species. 

Hemlock bark of younger tree

Hemlock bark of a mature tree

Hemlock cones

Spruce Needles

Spruce Bark

More Resources

Many of our partnering agencies and other groups across state are working to help prevent the spread of HWA, educating the community, and offer other opportunities. We encourage you to use these group’s resources as well and consider working with them.