The Hemlock and Hemlock Wooly Adelgid

(Updated: May 30, 2024, 10:05 a.m.)

Hemlocks are magnificent evergreen trees that play a crucial role in the ecosystems of North America.  Hemlocks have graceful, feathery foliage and a towering presence.  They provide habitat for wildlife, regulate water cycles, and contribute to the aesthetic beauty of forests and landscapes. However, these majestic trees are under severe threat from an invasive pest: the Hemlock Woolly Adelgid (HWA).

The Hemlock Wooly Adelgid

The Hemlock Woolly Adelgid (Adelges tsugae) is a tiny, aphid-like insect native to East Asia. It was first discovered in the United States in the 1950s and has since spread rapidly across the eastern states. The adelgid attaches itself to the base of hemlock needles, feeding on the tree's stored starches and injecting toxic saliva. This feeding disrupts nutrient flow, leading to needle loss, reduced growth, and ultimately the death of the tree if left untreated. The white, woolly egg sacs of the HWA are often visible on the undersides of hemlock branches, making early detection possible.

Hemlock Restoration Initiative

In response to the devastation caused by the HWA, the Hemlock Restoration Initiative (HRI) was established in Western North Carolina. This program is managed by WNC Communities and is a collaborative effort aimed to restore hemlock trees to their native habitats through various strategies.  The HRI held a Hemlock Treatment Demonstration at the Old Fort Picnic area on May 16.  The demonstration included proper identification of hemlocks and HWA, how to access the health of the hemlock, and different chemical treatment applications for HWA.  

If you are a homeowner or a landscape professional, treatment is simpler and less expensive than before.  If you are looking for information about proper treatment for the HWA, go to the Hemlock Restoration Initiative. They have a wealth of information on their website.