Hemlock Woolly Adelgid

The Hemlock Woolly Adelgid is a destructive, introduced pest of hemlock trees.  The adelgid is believed to native to Asia.  In china and japan the insect causes little damage due to several natural predators and the native trees resistance to the pest.  However in the US heavy infestations of the Hemlock Woolly Adelgid (HWA) can kill Canadian and Carolina hemlocks in as little as four years.  It is believed that the HWA was introduced in the US on imported ornamental hemlock.  Anne T. Lenox, Penn State