REGION– The Michigan Department of Agriculture and Rural Development (MDARD) is expanding the state’s interior box tree moth (Cydalima perspectalis) quarantine, effective December 11. Although not a threat to Michigan’s natural resources, this invasive pest can lead to significant defoliation and death of ornamental boxwood.
The quarantined area now includes the entire counties of Clinton, Eaton, Ingham, Jackson, Lenawee, Livingston, Macomb, Monroe, Oakland, St. Clair, Washtenaw, and Wayne. Under the quarantine, the whole plant, plant parts, and nursery stock of the genus Buxus, including all living and dead material, cannot be moved outside of the quarantined area. Holiday greenery, such as wreaths, boughs, and grave blankets are exempt from this restriction if moved from October 15 through January 1.
“By expanding this quarantine, we hope to keep box tree moth from moving to new areas in the state, while minimizing the impact on Michigan’s horticulture industry,” said Mike Philip, MDARD’s Bureau Director of Environment and Sustainability. “MDARD is working closely with Michigan’s horticulture industry to ensure the safe trade of plant materials, and to minimize the impact on nurseries, greenhouses, and retailers both inside and outside of the quarantined area.”
Box tree moth caterpillars are green and yellow with white, yellow, and black stripes and black spots. Adults have white wings with dark brown borders and a distinctive white dot or mark in the middle of each forewing.
Box tree moth may not be easily recognized at the beginning of an infestation, because young caterpillars 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 the plant. Larvae skeletonize the leaves and feed on the undersides, causing defoliation and dryness and eventually leading to the plant’s death.
“In the spring, residents within the quarantine area should examine their boxwood for symptoms of box tree moth. Suspected cases should be reported online at www.Michigan.gov/ReportBTM,” added Philip. “By reporting any signs of the pest, Michiganders can help us determine the scope of the infestation and reduce the spread.”
After MDARD officials have confirmed a suspected case, residents are advised to remove infested branches or, for heavy infestations, cut the boxwood from its base (it should grow back from its roots). All boxwood debris should be double bagged in plastic and discarded with household trash. Some municipalities or trash vendors may have restrictions surrounding plant material disposal—check with your local waste management entity for guidance. For more information, and a list of insecticides known to be effective against destructive caterpillars, view the Michigan State University Insecticide Options for Box Tree Moth Management.
The box tree moth quarantine can be found here. Additional information about box tree moth can be found at www.Michigan.gov/invasives.
