The Box Tree Moth (BTM) caterpillars are green and hairy, with black stripes and white dots. They grow to about 1 to 2 inches. Adults are white with a thick brown border on the wings and are active at night.

Figure 1: Box Tree Caterpillar found in Kent County, Delaware, Grace Ferry, University of Delaware Cooperative Extension

Figure 2: Box Tree Moth, Szablocs Sáfián, University of West Hungary, Bugwood.org

Habitat

The Box Tree Moth is native to subtropical regions of Asia. The USDA confirmed its presence in New York in 2021. They primarily feed on Buxus spp., but other hosts could include: Euonymus alatus, E. japonicus, or Ilex chinensis after nearby boxwoods are defoliated.

Life Cycle

Overwintering larvae emerge and feed in late May to early June. Adults will live up to 2 weeks after emergence. Females will lay their overlapping yellowish eggs (5-20) on the underside of boxwood leaves. Delaware may have 2 -3 generations.

Damage

Damaged boxwood leaves may appear “peeled” or only have the mid-rib left behind. Heavily infested shrubs may appear brown, “see-through” or “torched.” Caterpillars produce webbing and hide among leaves and twigs as they feed or pupate. They also consume the bark of twigs when few leaves remain which can kill the plant.

Figure 3: Damage from Box Tree Moth, Ferenc Lakatos, University of Sopron, Bugwood.org

Treatment

If caterpillars are small enough Bt is an effective treatment. However, if they are bigger other treatments are spinosad or pyrethroids like bifenthrin.

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