LENAWEE COUNTY, Mich. – The invasive box tree moth (BTM) has been found at two residences in Clinton in Lenawee 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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In May 2021, potentially infested boxwood plants were shipped to retail locations in several states -- including six in Michigan. It was identified in three of the six Michigan facilities.
Officials do not know if the box tree moth populations found in Clinton are linked to those shipments or if the pest entered the state a different way.
“Box tree moth poses a serious threat to our boxwood industry,” said Mike Philip, Pesticide and Plant Pest Management Division Director with the Michigan Department of Agriculture and Rural Development. “We are in the assessment stage of this response, and we are asking Michiganders to look closely at their boxwood plants and report any signs of this pest so we can determine the scope of this infestation and work to reduce the spread.”
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.
“MDARD is developing a survey plan to further determine the extent of the infestation,” added Philip. “But Michiganders can be a tremendous help by being on the lookout for box tree moth and reporting it.”
Read: Meet Michigan’s 8 invasive insects: What they are, the damage they cause and what to do about them
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.