Box Tree Moth
The box tree moth, Cydalima perspectalis, is not known to be present in the United States but poses a serious risk to our ornamental and landscape plantings if introduced. These insects attack a variety of boxwood species, commonly used in landscape plantings and for hedges and topiaries. While non-destructive in its native East Asian region, the larvae feed extensively on the leaves of boxwoods in nonnative regions, weakening and desiccating the plants. Dense moth populations often result in complete defoliation and death.
Larvae feed on boxwood leaves as well as the bark on stems, weakening and drying these popular and hardy plants. When densely populated, the pest can disfigure hedgerows and defoliate plants completely, often resulting in plant death. This damage greatly reduces the economic value of the plants and landscapes.
Boxwood are widely used across the landscape and ornamental industries. The commercial boxwood industry in the United States is valued at $170 million. According to the 2009 Hort Specialties Census, boxwood ranks first in production and second in sales among woody ornamentals in the U.S. Boxwood is already under threat from a newly introduced disease—boxwood blight. A box tree moth introduction would further threaten the U.S. boxwood industry.
The most likely pathway for box tree moth has been through the shipment of infested ornamental boxwoods. In 2018, the moth was detected in two locations in Toronto, Canada. Should it establish there, it could spread naturally into the U.S. Both male and female moths are strong fliers and have the potential to disperse 7–10 km annually.
Box tree moth larvae feed on all known species of boxwood.
Plant defoliation progresses as box tree moth larvae feed on leaves and spin webs among the twigs. Signs and symptoms on the plant may include:
- leaves with edges consumed to complete defoliation
- skeletonized leaves look like tan thin, paper from early feeding damage
- dieback or death of plant
- loose webbing among the leaves and twigs
- round, green frass (excrement) caught in webbing
- molted black larval head capsules
If you see any of these signs or symptoms on a boxwood, look more closely for the insect’s presence.
Box tree moths are most recognizable as larvae found feeding within the plant. Larvae are light green with black stripes and white dots. They have a shiny black head and grow up to 4cm (1.5 inches) in length.
Think you've spotted this pest?
If you think you've found this pest in your landscape contact your local extension office to see about sending in a sample.
Find your local extension office here.