Gypsy Moth Defoliation Decreases Nearly 75 Percent in Virginia

Officials with the Virginia Department of Forestry (VDOF) say that the gypsy moth declined significantly this year. The insect defoliated 29,048 acres in the Commonwealth, a substantial decrease from the 112,340 acres damaged in 2008. Nearly 12,288 acres of defoliation occurred across the George Washington – Jefferson National Forest, much of it close to the West Virginia state line. An additional 7,473 acres affected Shenandoah National Park. Unlike last year, a majority of the defoliation was classified as “light.”

Wet weather is credited with reducing the impact in Virginia. VDOF Forest Health Specialist Dr. Chris Asaro said, “Gypsy moth caterpillars often succumb to disease caused by a fungus and a virus, especially when cool, wet weather occurs during their feeding period in May. In most areas of the state, precipitation occurred every few days during the spring, and the fungus thrived in these conditions.” Caterpillar mortality meant that there weren’t mature caterpillars to feed on leaves, thereby reducing defoliation this year, and fewer adults to lay eggs for next year.

“So, next year’s defoliation levels could continue this downward trend,” Asaro added.

While overall defoliation levels were lower, intense defoliation pressure in recent years has resulted in locally heavy mortality of oak trees. Some of the areas with the heaviest mortality include Giles, Roanoke, and Augusta counties. In southwest Roanoke County, the forests along Poor Mountain and Bent Mountain have been devastated by gypsy moth since 2005; thousands of acres of dead oak trees cover much of this landscape. Chestnut oak growing on poor soils tends to be the predominant species affected, but many other tree species are also susceptible.

John Miller, VDOF’s director of resource protection, said, “The fire danger in these areas is significantly greater due to the high number of dead trees. Over time, the large standing dead trees also create special dangers for our firefighters, making an already tough job even more dangerous.”

Read more of the VDOF news release or visit the VDOF Forest Health section for more information.