The eastern hemlock was designated the official tree of Pennsylvania in 1931. There still are an estimated 124 million hemlock trees greater than 5 inches in diameter alive in Pennsylvania which is nearly 13 million fewer than in 2004. The non-native, invasive hemlock woolly adelgid is literally draining the life out of the eastern hemlock.
The HWA, an invasive aphid-like insect native to Japan was originally introduced to the Western United States in the 1920s. It was first discovered in the eastern United States in 1951 and is now reported in 18 states including Pennsylvania.
HWA is a sap feeder that inserts its mouth into the hemlock tree and remains there for the rest of its life feeding on the stored starches of the tree. Usually, the trees die within four to 10 years. Although all species of hemlock are vulnerable to attack, severe damage occurs in eastern hemlock trees.
Charles Bier, senior director of conservation science for the Western Pennsylvania Conservancy said:
I’m alarmed, and I have been waiting for it, seeing the devastation in the eastern and central parts of the state for the past 20 years. This has big implications for Pennsylvanians who have a sense of place in the native landscape.
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