Hemlock Woolly Adelgid (​Adelges tsugae)

Hemlock woolly adelgid (HWA) is a microscopic insect, less than 1/16 inch in size. Infested hemlocks have white wool-like coverings on the underside of branch tips called ovisacs, which contain egg-laying adults. These ovisacs can be seen on infested trees from late fall to early summer. HWA can cause tree mortality within 4-20 years of infestation.  In the fall and winter, developing adelgids feed on twig tissue, including starch reserves critical to the trees survival.

Birds are a primary vector of HWA spread, so moving bird feeders away from hemlock trees is recommended.