by Kate Shunney
Plant and bug experts in West Virginia are on alert about a new pest that is damaging boxwoods as they feed on the shrubbery and infest areas around them.
Morgan County Extension Agent Cindy Smalley said she has gotten reports of defoliation of box woods in different areas of the county, from the public garden areas on the Fairfax Green to the cemetery at Mt. Zion Church at Spohrs Crossroads. Private homeowners are also seeing the moth damage.
The box tree moth has only been reported in Morgan and Berkeley counties in West Virginia as of 2025. The pest is native to East Asia and was first detected in New York in 2021.
Other states have now seen the moth, including Delaware, Massachusetts, Michigan, Ohio, Pennsylvania and Virginia.
WVU Extension experts say that adult moths are strong fliers and can move several miles.
The box tree moth caterpillars are green with black, yellow and white stripes, somewhere between .25 and 1.5 inches long. Adult moths will be white with brown margins on their wings, roughly 1.5 inches across.
Boxwood shrubs are the only plant that the box tree moth seems to attack, said Extension experts.
“Young larvae feed on the underside of the leaves, which gives them a ‘peeled’ appearance. Older caterpillars will consume entire leaves, except for the midrib. Caterpillars also create webbing between leaves with their silk. Infested plants will have patchy defoliation with webbing in light infestation and greater defoliation in heavy infestations,” the Extension alert says.
“Adult female box tree moths lay their eggs… in a gelatinous mass on the underside of boxwood leaves. Box tree moths overwinter as larvae. Once temperatures rise, overwintering larvae emerge and typically begin feeding in March, continuing until they pupate in late April to early May,” says the U.S. Department of Agriculture.
As they grow, the pest spins silken webs to hold leaves together to create a feeding area. They tend to feed on leaves in the lower portion of host plants but live in the upper portion of the boxwood.
Small infestations of the worm or moth on boxwoods can be treated by pruning the plant and destroying the affected branches.
Pesticides that contain Bacillus thuringiensis (BT) as an active ingredient can be highly effective against the box tree moth and lepidopteran species of pests.
“Another biopesticide that has shown high efficacy against caterpillars is Spinosad. Horticultural oils, insecticidal soaps, and chlorantraniliprole are reduced-risk insecticides that also should be effective on caterpillars. Last, there are several broad-spectrum insecticides, such as pyrethroids, labeled for control of other caterpillars on ornamentals that should also provide control. However, these products should be avoided because they are more toxic to beneficial insects and can cause outbreaks of secondary pests,” say WVU Extension specialists.
Large infestations of the caterpillar and moth can decimate boxwoods in an area. Damaged shrubs should be removed and destroyed to minimize any spread of pests.
Residents who have caterpillar of moth damage are encouraged to contact the Extension office at 304-258-8400 for guidance and report the bug damage to the state Department of Agriculture.
Any boxwood damage or activity suspected to be by box tree moths should be reported to the West Virginia Department of Agriculture at 304-558-2212 or bugbusters@wvda.us.