Boxwood plants across Vienna yards and gardens face a new threat: the box tree moth, an invasive pest whose caterpillars can strip shrubs bare and kill them.

The Virginia Department of Agriculture and Consumer Services (VDACS) first confirmed the moth in Virginia in July 2025, detecting it at four sites in Clarke and Loudoun Counties. The moth has not been confirmed in Fairfax County, but Maryland's expanding quarantine signals the pest is moving through the mid-Atlantic. Northern Virginia Magazine reported Wednesday, Aug. 26, that Maryland has now quarantined eight counties.

For Vienna-area homeowners, boxwoods are among the most common landscape shrubs lining driveways, framing porches and filling garden beds. A Virginia Tech fact sheet notes the moth feeds on boxwood species commonly used in Virginia landscaping and grown in Virginia nurseries.

What to look for

The caterpillars are lime green with thin black stripes and grow up to 1.5 inches long. They chew leaves from the underside, leaving brown, skeletonized foliage. Loose silk webbing around branches signals active feeding. Adult moths have white wings with a brown border and fly mostly at night.

Caterpillars are active from approximately April through October. The moth can survive temperatures as low as minus 22 degrees Fahrenheit, according to Virginia Tech, meaning it overwinters throughout all parts of Virginia. It may produce up to three generations per year in the state's climate.

Don't spray first

The University of Maryland Extension advises that applying preventative pesticides to boxwoods will not effectively control box tree moth. Unnecessary applications can harm beneficial insects. Homeowners should confirm the moth is present before treating.

Treatment available and how to report

VDACS is offering to treat boxwood plants if the box tree moth is confirmed on a property. Homeowners who notice browning leaves, defoliation or webbing on their boxwoods should file a report through the agency's Invasive Species Reporting Tool, available online. The VDACS Office of Plant Industry Services can also be reached at 804-786-3515.

In its July 2025 press release, VDACS said early detection and rapid response are vital for managing any newly introduced invasive pest.

Maryland quarantine expanding

Maryland's Department of Agriculture on Monday, Aug. 24, expanded its box tree moth quarantine to four additional counties: Caroline, Cecil, Kent and Queen Anne's. The state first issued quarantine orders in March for Allegany, Frederick, Garrett and Washington counties. The quarantines require businesses that grow and ship boxwoods to obtain inspection certificates and sign compliance agreements before moving plants in or out of those areas.

No quarantine has been announced for Virginia counties. VDACS has said it plans additional surveys but has not announced specific dates.