The Michigan Department of Agriculture and Rural Development’s (MDARD) interior Box Tree Moth (BTM) quarantine currently restricts the movement of Boxwood to within 12 quarantined counties: Clinton, Eaton, Ingham, Jackson, Lenawee, Livingston, Macomb, Monroe, Oakland, St. Clair, Washtenaw, and Wayne. The MDARD quarantine was updated on May 30, 2024 to reflect the release of a new federal order on BTM issued by the U.S. Department of Agriculture (USDA) on May 22, 2024. 

A team comprised of experts from both the USDA and the National Plant Board worked to develop a set of requirements to allow interstate movement from quarantined counties while minimizing the risk of spreading this invasive pest. The new federal order allows states the authority to issue compliance agreements, and MDARD is ready to assist growers with this opportunity!

Firms within the 12 quarantined counties distributing boxwood within the quarantine area are required to continue operating under an interior compliance agreement. The new federal order now allows firms inside the quarantined area to ship outside of the quarantined area by entering into a more stringent compliance agreement. These requirements are meant to limit the spread of this destructive pest and include developing a detailed pest management plan that involves scouting, trapping, pesticide treatments, and notifying receiving states’ Departments of Agriculture of the intended shipments. If interested in shipping outside of the quarantine area, please email MDARD-NurseryCE@Michigan.gov.

Another important update to USDA’s federal order is that firms will no longer need to tag their Boxwood plants with the previously required "Regulated Article” plant tag or sticker.

About Box Tree Moth

If you are located outside of the quarantined counties, you can help MDARD identify populations of Box Tree Moth. The 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 Boxwood 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 and summer, Michigan residents should examine their Boxwood for symptoms of Box Tree Moth. Suspected cases should be reported online at www.Michigan.gov/ReportBTM.  By reporting any signs of the pest, Michiganders can help us determine the scope of the infestation and reduce the spread.

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: https://www.canr.msu.edu/resources/insecticide-options-for-box-tree-moth-management-ir4-project. Additional information about Box Tree Moth can be found at www.Michigan.gov/invasives.