Box Tree Moth confirmed in New Castle County

A box tree moth, an invasive pest recently confirmed in New Castle County. (Photo courtesy of Delaware Department of Agriculture)

The Delaware Department of Agriculture has confirmed the presence of a box tree moth (Cydalima perspectalis) in New Castle County during inspections of traps set along the New Castle County-Kent County border.

The box tree moth is a federally regulated pest that primarily targets boxwood species (Buxus spp.), a popular evergreen shrub used in landscaping. Left unchecked, it can cause extensive damage and even kill the plants.

This is the first discovery of the insect in New Castle County. Delaware first confirmed a box tree moth in Kent County in July 2024, three years after the pest was first detected in the United States in 2021.

“We continue to work closely with our partners at the U.S. Department of Agriculture and University of Delaware extension to monitor this invasive pest,” said Jeffrey Brothers, Delaware Department of Agriculture’s Plant Industries Administrator.

“A box tree moth caterpillar can quickly defoliate boxwoods and remain active until September or October. Homeowners and nurseries should be on the lookout for signs of damage to their plants.”

The caterpillars can grow up to 1.5 inches and are identified by their lime-green color, black stripes, white spots, hair, and shiny black heads. They produce heavy webbing on plants and can completely defoliate host shrubs. After leaves are stripped, they feed on bark, eventually killing the plant.

Adult box tree moths typically have white wings bordered with thick brown. They are most active at night and can sometimes be mistaken for melonworm moths.

What residents can do

Delawareans are urged to help prevent the spread of the pest by monitoring and managing infestations. Signs to watch for include brown or skeletonized leaves, defoliation, and webbing with caterpillars present.

Guidance on insecticide options is available here. Officials remind homeowners that “the label is the law. Always read and follow the pesticide label.”

For infestations, homeowners are advised to remove affected boxwood branches or, in severe cases, cut shrubs to the base. Plants can regrow from the roots, but debris must be double-bagged in plastic and placed in the trash.

Nursery businesses are encouraged to closely monitor their boxwoods and report any detections to the Delaware Department of Agriculture at DDA_PlantPests@delaware.gov.

More information is available at the U.S. Department of Agriculture and University of Delaware Cooperative Extension websites.