trees that cannot be completely sprayed with insecticidal soaps or foliage insecticides. The most common insecticide is imidacloprid, which can be effective for several years if absorbed through the soil. Tree roots absorb and transport the product into the foliage and kill hemlock woolly adelgid. Soil drenches must be applied when soil moisture is adequate for the tree roots to absorb the product. These products should not be used in close proximity to bodies of water. Trunk injections are used for large trees that are near water or where soils are too rocky for soil injections or drenches. The chemical is injected directly into the tree and transported to the twigs and needles where the hemlock woolly adelgids are feeding. Adequate soil moisture is also necessary for the tree to take up these products. Significance Hemlock is a vital component of the New England forest system, and is the third-most prevalent tree in Vermont. It provides protection from erosion along stream banks, food for deer and wildlife, and shelter for deer in winter. The tree is also valued both as an ornamental and as an important source of lumber. Unlike the balsam woolly adelgid that attacked only mature balsam fir, HWA infests hemlocks of all ages. Where hemlocks occur in pure stands in that region, the most commonly observed tree species to succeed it is black (sweet) birch. In the southern extreme of its range, hemlock typically occurs not in pure stands, but in linear riparian areas and other moist sites. Succession in these areas is affected by the presence of Rhododendron maximum, which often coexists with hemlock, and because of a combination of influences restricts regeneration to shade and otherwise understory-tolerant plant species. Major changes in ecosystem structure and function, including hydrologic processes, are expected with the loss of hemlock. Loss of the eastern and Carolina hemlock from hemlock woolly adelgid infestation will likely result in many ecological shifts in eastern North America. The understory of hemlock forests is characterized as dark, damp, and cool and is an ideal habitat for various other organisms. The moist environment is preferred by many native amphibian species, particularly newts and salamanders. Some species of birds have close association with the hemlock, especially during mating and nesting periods. Aquatic systems adjunct to hemlock stands are also affected by the trees' decline. Brook trout is a native fish species to the eastern United States