American Forest Foundation Blog has article about hemlock woolly adelgid

A silent killer is blazing a trail through the Appalachians, leaving countless dead hemlocks in its wake. The assassin is a tiny invasive insect from Japan, the hemlock woolly adelgid (HWA). It is stealthy and brutal, causing 80-90 percent mortality of eastern and Carolina hemlocks. Many fear the loss of these ecologically significant and charismatic [...]