Hope growing that Pennsylvania’s state tree, the Eastern hemlock, can beat invasive adelgids

The fight is far from over, but scientists are increasingly optimistic that once-ubiquitous Eastern hemlock trees might, with help, bounce back from a 50-year assault by invasive woolly adelgids.
The aphid-like insects, native to the Pacific Northwest and Asia, found their way to the eastern U.S. in the early to mid-1900s and have been spreading and killing hemlocks by the millions ever since. But a combination of bio-controls, insecticides, habitat doctoring and a disease-resistant hemlock hybrid – plus the discovery of native trees that are somehow immune – may keep the beloved and valuable tree from disappearing in Eastern forests.
That’s an outcome that arborists would not have predicted with confidence 20 years ago.