A New Threat to North American Boxwoods

BOX TREE MOTH:

A New Threat to North American Boxwoods

BTM caterpillar with frass and webbing.

By Amy Michael

Cooperative Agricultural Pest Survey Coordinator North Carolina Department of Agriculture & Consumer Services (NCDA&CS)

The box tree moth (Cydalima perspectalis, BTM) is native to eastern Asia and has become a serious pest in Europe. Although this moth is a relatively new pest to North America, an established population of BTM was found in Ontario, Canada, in 2018. The BTM caterpillar feeds on boxwood (all Buxus spp.). The larvae start by chewing away at leaves; heavy infestations will completely defoliate shrubs and then begin to feed on the bark, girdling and ultimately killing the host plant. BTM can have two to five generations per year, depending on temperature, and would be expected to be active April through October in an environment like North Carolina’s. In introduced areas where the pest has the minimum two generations per year, boxwood stands have declined by more than 95% within a decade. Given the ample host availability and their ability to rapidly reproduce and spread, BTM could become a major pest to North Carolina nurseries and landscapes across the country.

Damage caused by BTM feeding.

Ferenc Lakatos, University of Sopron, Bugwood.org

BTM adult, typical coloration.

Szabolcs Sáfián, Bugwood.org

BTM adult, dark coloration.

Szabolcs Sáfián, Bugwood.org

The BTM has not yet been found in North Carolina, but it could easily be introduced through shipments of infested boxwood. Early detection and swift reporting are critical to safeguarding North Carolina boxwood production! You can help by keeping an eye out for these signs of infestation and damage: • Bright green larvae, with shiny black heads up to 2 inches long, feeding on boxwood foliage and stems • Webbing with green balls of frass (caterpillar excrement) • Defoliation, chewed boxwood leaves, or papery, dried out foliage. BTM is the only pest that

defoliates boxwood in North America!

• Adult moths may be present near host plants and will lay eggs on boxwood leaves

Report suspect BTM infestations to NCDA&CS by emailing a photo to newpest@ncagr.gov or by calling 1-800-206-9333.