Box Tree Moth Update: Symptoms to Monitor, Tips on Mitigation
July 27, 2021 
Extensive feeding damage from the box tree moth. Photo by Ferenc Lakatos, University of Sopron, Bugwood.org
On May 28, 2021, the USDAs Animal and Plant Health Inspection Service (APHIS) announced that it had confirmed the presence of box tree moth (BTM), Cydalima perspectalis, in the continental U.S. and was working to contain and eradicate the invasive pest.
Growers and landscapers can learn more about the situation in two upcoming webinars. First up is a Horticultural Research Institute presentation that will provide an overview on ongoing BTM research, an update on APHIS eradication efforts, and a closer look at BTM biology, host range, and eradication/mitigation options including trapping/lures and pesticide options.
Registration for this webinar is available here.
On Aug. 5, Michigan State University Extension will partner with Clemson University to offer a free webinar on topic that will include signs of BTM and actions to take to treat the moths.
According to a press release from APHIS, between August 2020 and April 2021, a nursery in St. Catharines, Ontario, shipped boxwood (Buxus species) that may have been infested with box tree moth to locations in six states — 25 retail facilities in Connecticut, Massachusetts, Michigan, New York, Ohio, and South Carolina — and a distribution center in Tennessee.
The box tree moth was detected at three locations in Michigan this spring, but the Michigan Department of Agriculture and Rural Development (MDARD) and USDA APHIS have removed the threat in those locations.
In addition to the webinar, MSU Extension is also partnering with the Michigan Department of Agriculture and Rural Development (MDARD) and APHIS to implement an early detection insect trapping program with citizens to learn if the pest has been introduced elsewhere in Michigan. While MDARD nursery inspectors are actively inspecting commercial boxwood crops for box tree moth, MSU Extension is also asking nursery growers who currently grow boxwood or landscapers who have recently installed boxwoods in either 2020 or 2021 to check them for signs of infestation as described below, to consider use of box tree moth pheromone traps, and to report any positive or suspicious finds.
Signs of the Box Tree Moth
Box tree moth caterpillars only feed and reproduce on boxwood (Buxus spp.). The first symptoms are defoliation of boxwood leaves. If you begin to see signs of damage, check the boxwood plants for caterpillars (0.25 inches after egg hatch to 1.5 inches long when mature), which are lime green with black stripes and have white spots and hairs. The caterpillars have a shiny black head. As feeding progresses, caterpillars eat the leaves and bark, leaving only the midribs of leaves. With extensive feeding damage, you will see webbing from caterpillar silk and the eventual death of the plants.
Nursery growers should spray all boxwood shrubs grown in containers or in the field two times this season (late July and early September) with a pyrethroid insecticide labeled for use in nurseries (i.e., bifenthrin, cyfluthrin, permethrin, resmethrin, cypermethrin, lamba-cyhalothrin, sumithrin).
Learn more here.
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