Shenandoah NP – Aerial Spraying UPDATED 5/13/24

Hiking Safety



Update: Due to weather, the park has expanded the window for aerial spraying to include today through Friday, May 17. The aerial spraying is to suppress nonnative spongy moth caterpillars. The spray is not toxic to humans or pets and can be easily washed off with soap and water. See below for details.


Shenandoah National Park will conduct an aerial spraying program in partnership with the U.S. Forest Service (USFS) to suppress nonnative spongy moth caterpillars along sections of Skyline Drive (miles 39 to 51) and in the Skyland and Big Meadows areas in May. These are near approximate NOBO miles 925 to 936 on the Appalachian Trail (A.T.). Because weather conditions are unpredictable, officials do not know the exact dates of the spraying operation. Based on history, the spray window will likely be from May 15 through May 17 or May 20 through May 21. A total of 3,150 acres will be sprayed from a specialized helicopter between 6:30 a.m. and 12:00 p.m. on two mornings. Once a date has been established park officials will notify the public via signage, handouts at entrance stations, its website, and social media.

The park will be using a naturally occurring bacteria – Bacillus thuringiensis var. Kurstaki, or Btk, as an aerial pesticide. Btk is widespread in natural ecosystems and is not harmful to humans, pets, plants, or most beneficial insects. The spray will not cause harm to painted surfaces and can be removed with soap and water. Btk is registered with the U.S. Environmental Protection Agency and is sanctioned by the U.S. Department of Agriculture for use against spongy moths.

Hikers in these areas during spray operations may hear noise from the helicopter and may be misted with the spray, which is not toxic and can be easily washed off skin, clothes, and gear with soap and water.

For more information including an FAQ, visit Shenandoah’s webpage on spongy moth treatment.