The arrival of the emerald ash borer into Shenandoah National Park heightens the concern over what this invasive insect might do to the park's forests, and reinforces why the park asks that you not bring firewood into the park.
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.
A single adult emerald ash borer was found in the northern end of the park. Shenandoah officials can't say whether there are others in the park. But park staff, in cooperation with the Virginia Department of Forestry, will soon survey the Dickey Ridge area. Shenandoah officials say "the beetle (and possibly others) may have moved on its own or may have been transported by firewood, though park regulations prohibit bringing firewood into Shenandoah from outside."
Ash trees are a significant component of Shenandoah National Park’s ecosystems. They account for 5 percent of Shenandoah’s trees and are widespread across the park. Communities that include ash comprise 65 percent of the park’s forests.
"If EAB becomes well established in the park, it could lead to large-scale ash mortality and cause impacts similar to what was seen when the park’s eastern hemlock trees were killed by hemlock woolly adelgid," said park Superintendent Jim Northup.
Because the emerald ash borer is a non-native pest, Shenandoah National Park is mandated to minimize its impacts on native ash trees. Park officials have been monitoring for the EAB since 2009. In April 2013, staff began conducting preventive EAB pesticide treatments on ash groves in developed areas and select sensitive plant communities in Shenandoah’s northern section. Park staff plan to continue and expand this project in spring 2014.
Project goals are to reduce hazard ash tree formation in developed areas and to preserve a portion of the park’s ash trees until approved bio-controls (e.g. parasitic wasps) become available. Shenandoah plans to treat 1,000-1,500 trees per year, as budgets permit.
Although complete eradication of EAB is not possible at this point, park managers are taking actions now, for public safety and to protect ash trees wherever possible.
EAB was accidentally introduced to North America from Asia and was first discovered in southeast Michigan in 2002. Since its introduction, the EAB has spread to 21 states and two Canadian provinces, killing more than 50 million ash trees.