Gypsy Moth Defoliation in Virginia - 2007

Click here to see a larger version of the map.Which areas in Virginia have been most affected by gypsy moth defoliation? Generally, it has been the mountainous regions in the northern and western part of the state. Approximately 73,408 acres were defoliated by this year’s Gypsy Moth population.

Gypsy moth first began moving through northern Virginia in 1984 and has gradually spread south and west. The head of this active front can be found along a line roughly running from Blacksburg to Danville to Virginia Beach. While gypsy moth defoliation does occur in Virginia’s Piedmont and Coastal Plain, it rarely occurs over large contiguous areas that can be easily mapped from the air. Among the reasons why mountainous areas are more susceptible to gypsy moth defoliation are the prevalence of preferred hosts (oaks), the relative stress on those host trees due to steep slopes and dry, rocky soils, and the amount of contiguous forest made up mostly of federal land. Many trees that see multiple years of heavy defoliation die, and the ensuing ecological changes to these areas can be profound.

The effects of all this past defoliation can still be easily seen from the air as a patchwork mosaic of different age classes and species composition. Stark white ‘ghost forests,’ which contain the skeletons of long dead oaks that remain standing, still dot the landscape in many places. Where oak regeneration is poor, forest composition will change and be more heavily influenced by tulip poplar, red maple and sweet birch. Mountainous areas to the south and west of Roanoke will begin to see gypsy moth defoliation for the first time in the coming years as the pest inexorably moves in that direction. The USDA Forest Service gypsy moth Slow-The-Spread Program has been very successful at doing just that, but ultimately the gypsy moth will make its way across the United States and will become a major force for change in many forested environments.