Hemlock woolly adelgid, Adelges tsugae, a native of Asia, on a garden plant in Salem, Oregon. First described in western North America in 1924, it is related to aphids and secretes a waxy/woolly coating to help protect it from predators. Heavy infestations can kill large trees in only a few years and entire native forests are now threatened. Control measures include the introduction of predatory beetles that feed only on adelgids, and foliar and systemic sprays.