Invasive Insect Killing Ash Trees Found in Shenandoah National Park


Shenandoah National Park confirmed in August the presence of a single emerald ash borer (EAB) beetle in the park. The adult beetle was caught in a surveillance trap in the Dickey Ridge Picnic Grounds, in the park’s northern section. Park staff and state foresters will soon survey the infestation in the Dickey Ridge area. This detection is 11 miles southeast of a 2012 beetle trapping nearby in Warren County. The beetle (and possibly others) may have moved on its own or may have been transported by firewood. Park regulations prohibit bringing firewood into Shenandoah from outside.

The emerald ash borer is a half-inch-long metallic green beetle that lays its eggs on the bark of ash trees. After hatching, larvae burrow under the bark, creating feeding tunnels that cut off nutrients and water flow to the tree. Trees typically die within three to five years of being infected.

Ash trees account for five percent of Shenandoah’s trees and they are present in 65 percent of the park’s forests.

Eradication of EAB is not possible at this point. It was accidentally introduced to North America from Asia and was first discovered in southeast Michigan in 2002. Since then, the beetles have spread to 21 states and two Canadian provinces, killing more than 50 million ash trees.

Because the beetles are a non-native pest, the park is mandated to minimize their impact on native ash trees, and monitoring for them started in 2009. In April the park began preventive pesticide treatments on ash groves in developed areas and selected sensitive plant communities in Shenandoah’s northern section. The goal is reduce hazard from dead trees in developed areas and to preserve a portion of the park’s ash trees until bio-controls such as parasitic wasps become available. The park plans to treat 1,000-1,500 trees per year.