Box Tree Moth Quarantine Now Includes Harford County

HARFORD COUNTY, MD — The box tree moth quarantine in Maryland has been extended into Harford County, officials said.

There are now nine Maryland counties under the box tree moth quarantine.

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In March 2026, a quarantine order was put in place for Allegany, Frederick, Garrett, and Washington counties due to their proximity to states with established box tree moth populations and a confirmed positive case recorded in Washington County.

In August 2026, the box tree moth quarantine was expanded into Caroline, Cecil, Kent and Queen Anne's counties. At that time, the box tree moth had not yet been spotted in Kent County, but its presence has now been confirmed.

Businesses that grow and ship boxwoods must have a certificate of inspection and complete a compliance agreement with the Maryland Department of Agriculture to move regulated items into or out of the quarantine zone.

Nursery owners and residents within the quarantine zone are encouraged to monitor their boxwoods and implement safeguards to limit pest risk. Early detection is key to preventing significant damage and loss, as well as the spread of the box tree moth, according to the MDA.

The box tree moth is a federally regulated insect that is native to East Asia. It was first identified in the United States in 2021 after being confirmed in New York and has spread to Delaware, Massachusetts, Michigan, New Jersey, Ohio, Pennsylvania, Virginia and West Virginia.

Caterpillars are lime green with thin black stripes and can be difficult to spot when small. Full-grown caterpillars can grow up to 1.5 inches. Adult box tree moths have white wings with a brown border. They are generally active at night and may be hard to detect.

The insect poses a threat to the region's nursery industries as it feeds primarily on boxwoods, an ornamental shrub used in landscaping. Early infestations are often hard to detect because the molting caterpillars generally feed on the undersides of leaves, and multiple generations can live on the shrub, as the box tree moth has a short development time.

This intensive feeding limits shrub recovery, and once it is fully defoliated, or cleared of leaves, the caterpillars will eat the bark, cutting off its supply of water and nutrients, a process called girdling. This will fully kill the shrub.

Residents can take the following steps:

• Monitor boxwoods in your landscape, looking for signs of defoliation, stripped back and/or caterpillar webs.
• If you suspect the presence of box tree moths, report it to MDA through this online form.
• Allow state and/or federal agricultural officials to inspect your boxwood plants to place detection traps.
• Prune out localized infestations and cut the tree down to its base, or completely remove the infected shrubs.
• Any infested shrub material should be double-bagged and placed in the trash so the moths do not escape.