LAPEER COUNTY, Mich. – The invasive box tree moth (BTM) has been detected in Lapeer County, according to the USDA.
While the BTM isn’t a threat to Michigan’s natural resources, widespread feeding can lead to significant defoliation and death of ornamental boxwood.
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The new population of box tree moth was discovered through monitoring efforts in collaboration with the USDA. Michigan Department of Agriculture and Rural Development (MDARD) has been conducting statewide trapping for the pest, while the USDA has focused on trapping around the perimeter of the other 12 counties currently under quarantine to track the spread of this pest.
MDARD implemented a box tree moth interior quarantine in 2023, which encompasses 12 southeastern counties: Clinton, Eaton, Ingham, Jackson, Lenawee, Livingston, Macomb, Monroe, Oakland, St. Clair, Washtenaw and Wayne. Authorities are working to update the quarantine to include Lapeer County.
“These surveying and trapping efforts play a significant role in helping monitor and slow the spread of box tree moth within our state,” said Steve Carlson, MDARD’s Pesticide and Plant Pest Management Division Director. “We’re continuing to work closely with Michigan’s horticulture industry to ensure the safe trade of plant materials and minimize the impact on nurseries, greenhouses, and retailers both inside and outside of the quarantined area.”
How to identify the box tree moth
Box tree moth caterpillars are green and yellow with white, yellow, and black stripes and black spots. The caterpillars only feed on boxwoods, which makes them easy to spot.
The adult box tree moth has two color forms. The most common is white wings with dark brown borders. The other is a darker form, which 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.
At the beginning of an infestation, younger 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 the plant.
Larvae skeletonize the leaves and feed on the back, causing defoilation and dryness. This eventually kills the plant.
What you can do
The Michigan Department of Natural Resources has offered the following tips:
- Check your boxwood plants for signs of box tree moth.
- If you see signs of box tree moth, please take a photo and report suspects online.
- Let state and federal agriculture officials inspect your boxwood for box tree moth.
- If a new population is confirmed, you may be directed to remove infested branches or, for heavy infestations, cut the boxwood from its base (it should grow back from its roots). Discard all boxwood debris by double-bagging it in plastic and putting it with your household trash.
You can click here to find photos and additional information about box tree moth or click here to learn about other invasive plant pests.