Do your hemlocks have a grayish appearance?  Are they dropping needles, especially on the interior of the branches?  Then, you may have an infestation of hemlock woolly adelgid. 

The hemlock woolly adelgid (Adelges tsugae), native to Asia, is a small, aphidlike insect that threatens tree health and sustainability of the Eastern hemlock and Carolina hemlock in the Eastern United States. The insect was first reported in the US in 1951 near Richmond, Virginia. By 2005, it was established in portions of 16 states from Maine to Georgia, where infestations covered about half of the range of hemlock. 

Hemlock decline and mortality can occur in as little as 3 to 6 years, so immediate action is necessary.  Unfortunately, once this pest is in an area, it will always pose a threat to the hemlocks, even those that have been treated. All hemlocks should be checked several times a year and treatments applied when woolly adelgid is spotted.

The hemlock woolly adelgid is tiny, less than 1/16-inch long, and varies from dark reddish-brown to purplish-black in color. As it matures, it produces a covering of wool-like wax to protect itself and its eggs from natural enemies and prevent them from drying out. This “wool” is most obvious when the adelgid is mature and laying eggs. It can be easily seen from late fall to early summer on the underside of the outermost branch tips of hemlock trees.

Once a Tree Tech certified arborist has diagnosed your trees, treatment can be started. A successful tree treatment option to control an infestation of woolly adelgid is to spray trees with horticultural oil. The horticultural oil is an insecticide consisting of super refined petroleum oil. The adelgids breath through their skin, so when this oil is sprayed on them and dries, it smothers them. We recommend two treatments per year for infested trees. This tree treatment provides protection, but don’t be fooled.  Even if it appears that the problem is “solved”, the pest will always return, so continue treatment each year to preserve the heath of your hemlocks.

For more information about Tree Tech’s many tree services, and to contact a certified arborist, visit http://www.treetechinc.net/ or call us at 888-873-3832.  We provide complete tree care services throughout Massachusetts and Rhode Island.