Invasive moth spreads to new state: Where else has it been detected?

RICHMOND, Va. (WRIC) — The Virginia Department of Agriculture and Consumer Services (VDACS) has confirmed the detection of a new invasive insect in the Commonwealth: the box tree moth.

Inspectors discovered the pest, Cydalima perspectalis, at four locations in Clarke and Loudoun counties. This marks the first time the species has been found in Virginia, though it has been detected in several other states.

The box tree moth poses a serious threat to boxwood plants (Buxus species), a popular ornamental shrub in Virginia landscapes, officials said. The caterpillars are known for their voracious appetites and can quickly strip boxwood of its foliage. If infestations are left untreated, the damage can lead to plant death.

VDACS officials said they will treat affected boxwood plants if the moth is confirmed on the property.

What is the box tree moth, and what should I look for?

Native to East Asia, the box tree moth and its caterpillars eat not only boxwoods, but nearly all box species, according to Michigan wildlife officials.

The caterpillars are lime-green, with black heads and “short, rigid hairs,” according to The Ohio State University Extension. Stripes on the caterpillars start as dark stripes that deepen in color as yellow stripes emerge.

Full-grown moths of the species are, in most cases, primarily white with brown around the edges of the wings. In some cases, the moths can be entirely brown with a few white spots, Michigan wildlife officials say.

When checking your boxwoods, look for brown or missing sections of leaves. The caterpillars may hide within the bushes, according to the USDA, while the moths are mostly active at night.

Where has the box tree moth been seen in the US?

The box tree moth has become a major pest in Europe and was first detected in the U.S. in 2021 in New York by the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS).

Since then, it has spread to several other states, including Connecticut, Delaware, Massachusetts, Michigan, Ohio, Pennsylvania, and South Carolina. Maryland and West Virginia also detected their first box tree moths this year.

In Europe, the quick spread of the moth is believed to be due to “an abundance of susceptible boxwoods coupled with the lack of natural enemies,” an article from The Ohio State University Extension explains. Boxwoods are not native to North America, however, which means there aren’t as many for the boxwood tree moths to feast on.

Officials in impacted states have enacted quarantines to help slow the spread of the box tree moth, while states nearby stand ready to act. In Wisconsin, for example, the detection of “a reproducing population” would likely spark a quarantine for that specific area. If a single box moth is intercepted, any potentially infested plants would be destroyed.

Early detection and rapid response remain key to managing all invasive species, VDACS emphasized.

What should I do if I see a box tree moth or caterpillar?

Virginia officials are urging residents to report any signs of damage to their boxwood plants online. Residents, nurseries, and landscapers in Wisconsin, where the species has not been detected, are encouraged to report a suspected infestation to the Department of Agriculture, Trade and Consumer Protection.

Even in states where the moth has been present for some time, like Michigan, officials ask for suspected infestations to be reported.

West Virginia officials say the natural pesticide Bacillus thuringiensis kurstaki (Btk) and other insecticides labeled for box tree moth control can be used if infestations are caught early enough. You’ll want to confirm whether you need to first report a suspected infestation in your state before using pesticide.