Oakleaf Caterpillar Defoliating Thousands of Trees in Central Virginia

The Virginia Department of Forestry (VDOF) has received dozens of calls from homeowners in Chesterfield, Goochland, Hanover and Powhatan counties concerned about the defoliation of hardwood trees on their properties.

“The variable oakleaf caterpillar is the insect responsible,” said Dr. Chris Asaro, an entomologist and manager of forest health for the VDOF. “Many people calling in think the culprit is the gypsy moth caterpillar, but those have already pupated and become adult moths.”

The variable oakleaf caterpillar is common throughout eastern North America. While it may attack a variety of hardwoods, its preference is white oaks.

Dr. Asaro said, “Outbreaks occur periodically. Older larvae devour the entire leaf with the exception of the leaf stalk and the main veins. Young larvae skeletonize the leaf.”

The variable oakleaf caterpillar is capable of stripping trees bare, but usually defoliation is less severe than that. Most healthy trees will recover and not suffer any long-term damage.

“Numerous callers have stated that they are hearing the caterpillars eating the leaves. In actuality, they are hearing the insects’ frass (excrement) dropping onto other leaves.”

Dr. Asaro said insect parasites and predators usually cause caterpillar populations to plummet after one or two years of heavy activity. Chemical control is not normally recommended in most situations, but may be used to protect high-value trees.

“At this point, however, most damage from feeding has already occurred, so it’s a little late for chemical control to be effective,” Dr. Asaro said. “Although the caterpillars can be a nuisance, they should finish feeding in another week or two.”

He also cautioned people not to handle the 1.5-inch-long caterpillars as they can spray a chemical mixture that contains formic acid when disturbed. This mixture is capable of blistering human skin.

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The Virginia Department of Forestry protects and develops healthy, sustainable forest resources for Virginians. Headquartered in Charlottesville, there are Forestry staff members assigned to every county to provide service to citizens of the Commonwealth. VDOF is an equal opportunity provider.

With nearly 16 million acres of forest land and more than 248,000 Virginians employed in the forest products industry, Virginia forests provide more than $30 billion annually in benefits to the Commonwealth.