Invasive Box Tree Moth Reported For First Time In W.Va.

An invasive moth species that has spread from Asia to North America was reported within the Mountain State for the first time this month, according to the West Virginia Department of Agriculture (WVDA).

Cydalima perspectalis, also known as the box tree moth, is native primarily to regions of East Asia including China, Japan and Korea. But the insect spread to Europe in the mid-2000s. More recently, it was first spotted in Canada in 2018, then the United States in 2021.

Now the box tree moth has been reported in a growing number of states, including West Virginia.

The WVDA confirmed June 18 that the moth had been detected in Berkeley County. Mike Arnold, the WVDA plant regulatory programs coordinator, said the mechanism for the insect’s widening spread is currently unclear.

“It’s moved into Delaware, Massachusetts, Michigan, Ohio and very northern Pennsylvania, now into West Virginia. All of those populations are not contiguous,” Arnold said. “West Virginia, obviously, is not next to an active population of box tree moths. … So it’s moving some way other than just normal flying.”

Some other invasive insects like the spongy moth have been spread through human means, for example fixing their eggs to vehicles bound for out-of-state travel.

Larvae of the box tree moth feed upon Buxus, also known as box trees, which are common ornamental shrubs used for landscaping purposes across the United States. Arnold said the species is prone to feeding upon box trees until they die.

“This particular pest feeds almost exclusively on that plant. And when it does, it feeds voraciously,” Arnold said. “Once a plant is infected with it, unless it’s treated, it’s very likely it will cause the death of that landscaping plant.”

Arnold said that is particularly concerning to agriculture officials due to the popularity of box tree shrubs in West Virginia and beyond.

“Boxwoods are in landscaping of houses or cemeteries or churches, or a lot of hedge material you’ll see,” he said. “It’s very foundational. People that aren’t in the trade would not necessarily recognize the boxwoods that they see. But if I were to stand next to one and point at it, almost everyone would say, ‘Oh, yeah, I’ve seen that plant before.’”

In a press release last week, West Virginia Commissioner of Agriculture Kent Leonhardt echoed those concerns.

“This pest poses a serious threat to boxwood plants,” he said. “Early detection is critical, and we’re asking homeowners and landscapers to keep an eye out and report any suspicious damage.”

The adult moth generally has whitish-green wings surrounded by a brown border. Its larvae are typically lime green in color, with black stripes. Signs of box tree moth infestation may include chewed leaves, webbing on or inside plants, severe bark stripping and the presence of small, green caterpillars, according to the WVDA.

The WVDA said the moths can be effectively treated using Bacillus thuringiensis kurstaki, a naturally derived pesticide that is safe to use on boxwoods and plant life.

Like Leonhardt, Arnold stressed the importance of reporting possible sightings of the moth and its larvae, even if just suspected. Residents can call the WVDA at 304-558-2212 to support suspected sightings, or contact Arnold’s office via email at bugbusters@wvda.us.

Arnold said that the presence of the moths does not pose an immediate risk to the state’s forests and agriculture. But he said minimizing risks to the landscaping industry and residents’ shrubs requires acting early.

“They’re very important plants to our nursery industry and to people that have them in their landscaping,” he said. “We just have to deal with the pest.”