LANSING, Mich. – The USDA’s Animal and Plant Health Inspection Service has confirmed the discovery of an invasive pest called the box tree moth at two residences in Michigan in Lenawee County, in the state’s lower east section.

The discovery follows the detection last year of potentially infested boxwood plants at several Michigan retail locations, which were followed up by confirmed infestations at three of the facilities. Officials said it’s not known if the most recent discoveries are linked to last year’s detection. Potentially infested boxwood plants were also sent to some other states last year, but there were no confirmations.

“This is a year later and this is the first incident where we’ve found it in the landscape,” said Robin Rosenbaum, plant health section manager at the Michigan Department of Agriculture and Rural Development (MDARD). “We don’t know if it came in from Canada naturally or if it came in on infested boxwood plants.” Rosenbaum noted that the pest has been detected in Tecumseh, Ontario, Canada, which is not far from Belle Isle, in Detroit. Rosenbaum said it’s quite possible the pest could have flown from Tecumseh and made it to Belle Isle on its own. Tecumseh is also close enough to Grosse Pointe, Mich., to have flown there, although it has not been detected in Grosse Pointe thus far.

“It’s definitely a concern to the nursery industry, because boxwood is a really high value plant,” Rosenbaum said. She said retailers in the United States sell $141 million worth of boxwood plants each year to residential customers. “Boxwood is a very valuable ornamental plant. It’s a nice little shrub and very popular. The only other state with a known infestation in the landscape is New York and look at its proximity to Canada. Anyone who’s planted boxwood should go out and check their plant for any signs of an infestation. Look for signs of feeding and webbing. Look deep down into the plant for webbing, like a spider web, or signs of feeding, not just on the outside of the plant. If you see any of it then please notify MDARD.”

Boxwood tree moth was first detected in Canada in 2018.

“The most important thing residential owners of boxwood plants can do is look out for the pest so we can get a handle on how extensive the infestation is at this time so we can make plans for next spring,” Rosenbaum added. “There is no quarantine on any area right now. It’s unlikely any retailers will be selling boxwood plants right now as people are focused on getting their Christmas trees and preparing for the holiday season. We just want residents to think about this right now and to inspect their boxwood plants. One good thing about this is boxwood tree moth is not a threat to the forest landscape.”

Box tree moth may not be easily recognized at the beginning of an infestation, because young larvae hide among twigs and leaves. Signs of infestation include chewed, cut or missing leaves, yellowing or brown leaves, white webbing and green-black excrement on or around plant. Larvae skeletonize the leaves and feed on the back, causing defoliation and dryness, eventually leading to the plant’s death. Caterpillars are green and yellow with white, yellow and black stripes, and black spots. They are easy to spot because they feed only on boxwood plants. The moth form has either white wings with dark brown borders, or solid brown wings with a white streak or spot on each forewing. Both forms have a distinctive white dot or mark in the middle of each forewing.

To report a detection of boxwood tree moth, go to the Michigan Department of Natural Resources Eyes in the Field website, https://www2.dnr.state.mi.us/ors/Survey/39 or call MDARD’s toll free number, 800-292-3939.