The U.S. Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS) has identified box tree moth (Cydalima perspectalis) in nurseries and greenhouses in the United States, including Michigan. This is the first detection of this invasive species in the nation. Box tree moth is not considered a forest pest because boxwood is not native to Michigan forests. However, if left unchecked, it could cause significant defoliation and death of boxwood in the landscape.
The Michigan Department of Agriculture and Rural Development (MDARD) is advising anyone, including landscapers, who purchased boxwood plants within the last two months to inspect their plants very closely for the invasive pest. Signs of infestation include silky webbing and possibly caterpillars located deep inside of the plants.
Box tree moth caterpillars are green and yellow with white, yellow, and black stripes and black spots. The caterpillars feed only on boxwoods making them easy to spot. Adult box tree moth has two color forms. The most common form has white wings with dark brown borders, while the dark form has 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.
“Boxwoods are commonly planted in North America as ornamentals with the largest plantings occurring in urban areas. In 2014, boxwood made up 15 percent of broadleaf evergreen sales in the United States with an estimated value of $126 million,” said Robin Rosenbaum, Plant Health Section Manager of MDARD’s Pesticide and Plant Pest Management Division. “Ensuring this pest is quickly contained is crucial to protecting the state’s boxwood.”
To further prevent the introduction of box tree moth into the United States, USDA APHIS issued a Federal Order on May 26, 2021, prohibiting importation of all boxwood (Buxus spp.), euonymus (Euonymus spp.), and holly (Ilex spp.) plants for planting from Canada.
If you see signs of box tree moth on your boxwood plants, contact MDARD’s nursery program at [email protected] with your contact information, photos, and when and where you purchased the plant. You may also contact Michigan State University Diagnostic Services at [email protected].
For more information on MDARD’s Pesticide and Plant Pesticide Management Division, visit Michigan.gov/MDARD.