Michigan Boxwoods Fall Prey to Invasive Box Tree Moth

The box tree moth, an invasive species that has been causing problems for boxwoods in Michigan since its arrival in 2018, continues to spread. The moth was first detected in Canada and is believed to have entered the US through a nursery in Toronto, where infested boxwoods were shipped to six states.

In Michigan, the box tree moth has been detected in 13 counties, with Genesee County becoming the latest addition to the list. The Michigan Department of Agriculture and Rural Development has quarantine procedures in place for these counties to slow the spread of the moth.

Before the moth's metamorphosis, it feeds aggressively on boxwood leaves, causing damage and discoloration. Homeowners can identify an infestation by looking for webbing, caterpillar droppings, and large amounts of frass. If caught early, homeowners may be able to kill the caterpillars with a pesticide called BT.

Caitlin Splawski, a floriculture educator with Michigan State University Extension, warns that the box tree moth could be the 'straw that broke the camel's back' for Southeast Michigan's boxwood problems. The state has already seen issues with diseases such as winter injury, drought stress, and psyllids.