Box Tree Moth: What It Is and How to Treat It
Box tree moth (Cydalima perspectalis) is an invasive pest from Asia that has been spreading through the northeastern United States and is considered a significant threat to ornamental boxwoods . While not yet confirmed widespread in Middle Tennessee, it is a pest to watch. Early identification is critical to limiting damage.
Identifying Box Tree Moth
The adult moth is white with brown wing margins and a wingspan of about 40 to 45mm. The larvae (caterpillars) are the damaging stage: pale green with black and yellow stripes, feeding voraciously on boxwood foliage from the inside of the plant outward. Webbing inside the shrub is often the first sign of infestation.
Watch for these signs of infestation:
- Webbing and frass (excrement) inside the boxwood canopy
- Skeletonized or stripped leaves
- Dieback that starts from inside the plant
- Visible green and black striped caterpillars
Why Boxwoods Are at Risk
Boxwoods are among the most widely planted ornamental shrubs in residential and commercial landscapes throughout Nashville. A severe box tree moth infestation can completely defoliate a boxwood within days and kill the plant if untreated.
Treatment Options
Bacillus thuringiensis (Bt) is an organic-approved bacterial insecticide effective against young larvae. It must be applied when larvae are actively feeding and requires good coverage inside the canopy.
Insect growth regulators disrupt larval development and are effective at preventing population buildup when applied preventively.
Pyrethroid-based products can provide rapid knockdown of active infestations.
Box tree moth produces multiple generations per year, so treatment timing matters. Applications should target early larval stages for best efficacy.
When to Call an Arborist
If you suspect box tree moth or notice unusual damage to your boxwoods, contact an expert arborist for a diagnosis. Many boxwood problems, including boxwood blight, Volutella dieback, and winter damage, can look similar. Accurate identification drives effective treatment.
Our plant health care team monitors pest pressure in the Nashville area and can develop a preventive or therapeutic treatment plan for your boxwoods.
