If you planted boxwood shrubs this spring, check them for box tree moth

A new invasive pest of boxwood, box tree moth, was found on a few boxwood shrubs sold in Michigan this spring.

Box tree moth adult.
Photo 1. Box tree moth adult. Photo by Didier Descouens via Wikimedia, CC BY-SA 3.0.

Box tree moth, Cydalima perspectalis, is a destructive pest of ornamental boxwoods (Buxus spp.) in Europe, where it was introduced from Asia. It was first discovered in North America in Toronto, Canada, in fall of 2018. It has not been previously found in the United States. Unfortunately, a few infested shrubs may have been sent to Michigan nurseries during spring 2021, despite being inspected and confirmed as free of boxwood tree moth by the source.

Although this may only be true for a few of the boxwood shrubs sold in Michigan this spring, the Michigan Department of Agriculture and Rural Development (MDARD) and the U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) are seeking assistance from residents of Michigan to check for boxwood tree moth caterpillars, pupae or adults.

Most adults have a white body and white wings surrounded by a wide brown band, giving them a distinctive appearance (Photo 1). However, some individuals may have entirely brown wings with a few white markings. Look for caterpillars, which are expected to be pupating now, or soon, by looking for silky webbing or lacey leaves where they have been feeding. The caterpillars are green with bold black stripes and black tubercles (Photo 2). Within another week or two, only pupae or adult moths will be found.

Caterpillar of box tree moth.
Photo 2. Caterpillar and some silk webbing produced by box tree moth caterpillar. Photo by Franz van Duns, Wikimedia Commons, CC BY-SA 4.0.

If you find box tree moth caterpillars or moths, report a sighting using MDARD's Eyes in the Field. If you find a similar caterpillar or moth on your boxwood shrubs, you can also contact Michigan State University Plant & Pest Diagnostics at pestid@msu.edu.

More detailed information and photographs can be found in the Pennsylvania State University Extension bulletin on Box Tree Moth.

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