Last week, Shenandoah National Park staff confirmed the existence of additional emerald ash borer beetles (EAB) in the park. Sixty-five adult beetles were caught in a surveillance trap near the park’s northern boundary and the town of Front Royal.
Due to the large number of EABs found in a single trap, the level of infestation is assumed to be fairly high. This new location is 4.5 miles north of the park’s initial EAB detection (a single EAB) last August in the Dickey Ridge Picnic Area.
The emerald ash borer is a half-inch-long metallic green beetle that lays eggs on the bark of ash trees. After hatching, the larvae burrow under the bark and create feeding tunnels that cut off nutrient and water flow to the tree. As a result, ash trees typically die within three to five years.
The beetle was accidentally introduced to North America from Asia and was first discovered in southeast Michigan in 2002. Since its introduction, EAB has spread to 23 states and two Canadian provinces, killing over 50 million ash trees.
Ash trees are a significant component of Shenandoah National Park’s ecosystems — a full 5 percent of the trees in the park are ash. However, ash trees are widespread, and occur in 16 of the park’s 34 vegetation communities. Collectively, these communities make up 65 percent of the park’s forest (126,883 acres). 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.
Since the EAB is a non-native pest, the park is mandated to minimize its impacts on native ash trees. Last April, due to the close proximity of EAB to the park at the time, staff began conducting preventive pesticide treatments on ash groves in developed areas and select sensitive plant communities in the northern third of the park. Park staff plans to continue and expand this project in spring 2015.
The 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. Park staff is planning to treat 1,200-1,500 ash trees per year (though complete eradication of the beetle is not currently feasible).
More information about the emerald ash borer can be found at emeraldashborer.info/.