Hemlock Woolly Adelgid (HWA)

The hemlock woolly adelgid (HWA) is an invasive, aphid-like insect native to Japan. It was first reported in the U.S. in Virginia in 1951. Since its introduction, HWA has spread to 19 states from Georgia to southern Maine, threatening the range of eastern hemlock (Tsuga canadensis). In New England, the insect feeds on and kills all sizes and age classes of hemlock usually within 5-10 years. Millions of trees have been infested or killed across the eastern U.S.

Ecologist Dave Orwig oversees HWA research at the Harvard Forest and across southern New England.

Related projects include:

• A 2017-2018 art installation and science communication initiative on the impacts of HWA: Hemlock Hospice.
• A 2017 study on the impacts of HWA on water yield.
• A 2016 study on the impacts of forest pests nationwide.
• A 2014 book: Hemlock: A Forest Giant on the Edge
• Long-term hemlock removal experiment
• Harvard Forest Global Earth Observatory 
• Hemlock eddy-flux tower
• K-12 education: "Woolly Bully" Schoolyard research protocol
• Assessing the Potential for Climate Change and Forest Insects to Drive Land-Use Regime Shifts

More information on Invasive Species