Using aerial mapping technology to assess potential Hemlock Woolly Adelgid spread

In Spring 2017, Adirondack Research partnered with NASA and the Adirondack Park Invasive Plant Program (APIPP) to assess potential for spread of the hemlock woolly adelgid (HWA), an invasive species affecting much of the lower eastern seaboard.

Effects of the Hemlock Woolly Adelgid (HWA) like these white egg sacs may appear benevolent at first. However, over the course of 4-10 years infestations can be lethal.


The Hemlock Woolly Adelgid (HWA)

Native to East Asia, the HWA affects the Eastern hemlock, a long-lived coniferous tree found across the Northeastern US. The HWA is a type of sap-sucking insect that causes the Eastern hemlock to lose its needles while inhibiting any new growth, effectively killing the tree over a period of four to ten years (Hanavan, 2015).


Our study area in the upper part of New York State. APIPP (dark green) is responsible for invasive species spread affecting the Adirondack Park, while SLELO (olive) is concerned with the Tug Hill Plateau Region.

Effects on New York State ecology and economy

HWA currently affects 414 counties in 20 US states (U.S. Forest Service, 2013). At present, the Adirondack Park’s Eastern hemlock population is largely unaffected by HWA (2 cases were reported in summer 2017), which thrives in a warmer climate that New York winters can typically support. However, as our winters get warmer, the risk for HWA spread will only get higher. Left free to spread, the HWA would wreak ecological havoc on animal and plant ecosystems across New York state which depend on the existence of the Eastern hemlock, a “foundation species,” for survival. An HWA infestation would also beget untold financial damage at local and federal levels. At its current levels, HWA incurs $100 million in residential property damage annually and is the precipitant of a steep $66 million in local government expenditures each year (Aukema et al, 2011). Our methods were designed to predict and mitigate such a costly spread in New York State.


Our current assessments for HWA proliferation in the Northeast with high risk for infestation shown in red and low risk in blue. At present, our study area (inset) is largely unaffected by HWA. However, risk for infestation is considerably higher in the lower part of the Tug Hill Plateau.

Our approach

Using airborne mapping technology, our project charted the location and density of Eastern Hemlock stands across New York’s Adirondack Park and Tug Hill State Forest. Using existing HWA presence data, we calculated the current risk of HWA infestation in the region according to our Eastern Hemlock population models and made projections for 2035.


Future measures

Our findings will be used by the Adirondack Park Invasive Plant Program (APIPP) to combat the spread of HWA. APIPP (link) is a coalition consisting of the Adirondack Chapter of The Nature Conservancy, the New York State Department of Environmental Conservation, the New York State Department of Transportation, and the New York State Adirondack Park Agency. APIPP supervises the Adirondack Partnership for Regional Invasive Species Management (PRISM). Seven other PRISMs exist throughout New York State to address invasive species like HWA.


Adirondack Research
28 St. Bernard Street
Saranac Lake, NY 12983
Phone: (518) 253-4112

Follow us

Visit Us On TwitterVisit Us On FacebookVisit Us On Linkedin