Adelges tsugae better known as Hemlock Woolly Adelgid is an invasive species that Destroys Eastern hemlock trees. The funny thing is that these insects arrived in the U.S. accidentally in shipments from Asia. The species was found in the 1920s in the West Coast and in the 1950s in the East Coast. Hemlock Woolly Adelgid Is commonly found in China, Japan, and northwestern North America.
Scientist say that Wooly Adelgid kills its host rapidly in a matter of years, stripping once luscious green Hemlock trees of all green. Hemlock woolly adelgid can be transported long distance on planting stock (as it did from Asia to the U.S.) The species can also spread from planted stock to native trees.
An interesting fact provided by the USDA Forest Service says that “In their native range, these populations of HWA ( Hemlock Woolly Adelgid) cause little damage to the hemlock trees they feed on as natural enemies and possible tree resistance has evolved with this insect pest.”