Severe winter cold helps reduce adelgid populations and slow their spread, so the recent trend toward relatively mild winters is actually facilitating the adelgid onslaught.
Another tree is being attacked by an alien insect, the hemlock woolly adelgid.
North America's once abundant Canadian hemlock (Tsuga canadensis) may soon become a relic and then a ghost, owing to the invasion of the woolly adelgid (Adelges tsuga annand).