Box Tree Moth Identification & Management
Report a box tree moth sighting
An image is required to submit a report. You can submit signs of damage or any alive/dead specimens found. Submitting a report may not receive a response and it is not a guarantee for treatment.
If you have any questions or concerns please email us at [email protected].
This is for box tree moth only NOT spotted lanternfly. If you need to submit a sighting for spotted lanternfly please submit it at the appropriate page.
About Box Tree Moth
Box tree moth (Cydalima perspectalis) is an invasive insect from East Asia that primarily feeds on boxwoods (Buxus spp.).
It was first spotted in North America in Ontario, Canada in 2018 and then spread to the U.S. through New York in 2021. It has since spread to nearby states like Pennsylvania and Delaware.
The box tree moth (BTM) is a capable flier and, along with human-assisted travel, it can potentially spread rapidly, impacting nurseries and Buxus plantings across the U.S.
Life Cycle of the Box Tree Moth
Box tree moth (BTM) primarily targets boxwoods (Buxus sp.). Although there is a possibility for certain Ilex, Euonymous and Murraya species to act as host plants under lab conditions, it has NOT yet been seen to do so in field conditions in North America. BTM also has a fast development time. In lab conditions, the time between egg hatch to adulthood takes a little more than a month. Although the number of generations per year in Maryland is unknown, it is expected to have multiple overlapping generations. Similarly, BTM’s phenology is unknown in MD so the time its various life stages appear throughout the year are estimates.
A generalized timeline can be seen here - PDF - 790.43 KB.
Larvae
BTM overwinter as caterpillars, primarily as third or even fourth instars, in a protective silk covering called a hibernaculum. As the weather warms around March, they will begin to feed again.
Early Instar Larvae: Indistinct green caterpillars that are around 0.5 inches with black head capsules.
Late Instar Larvae: As they mature, they develop black and white stripes with black dots. They are typically around 1.6 inches long.
Pupae
The caterpillars pupate from April to May, with a coloration similar to the larvae, developing in a silk cocoon among the leaves and webbing. The pupae are around 0.7 inches long.
Adults
Adults are around 1.7 inches in wingspan and wings are typically white with a thick brown border, and a brown head and abdomen. The front brown border of their forewing has small white crescent-shaped marking. There is also a much rarer brown form which has the same crescent marking. The first generation of adults emerges generally between May to July and then live for about two weeks.
Eggs
The adults lay pale yellow eggs in clusters of 5-20 on boxwood leaves. As eggs develop, a black spot (the head) appears inside them. Eggs take around 4 to 6 days to hatch, depending on the climate.
Identifying Boxwoods
There are typically three boxwood species planted as ornamentals: Buxus sempervirens, B. sinica, and B. microphylla, with many cultivars. Boxwoods are evergreen shrubs and can be identified by their opposing leaf arrangement, a white midrib on the underside of the leaves, smooth leaf margins and a distinct scent.
Boxwood Lookalikes
| Common Name | General Description | Evergreen vs. Deciduous |
|---|---|---|
Hollies (Ilex sp.) 
|
| Evergreen |
Euonymus (Euonymus sp.) 
|
| Both |
Privets (Ligustrum sp.) 
|
| Both |
Japanese Barberry 
|
| Deciduous |
Azaleas (Rhododendron sp.) 
|
| Both |
Signs of Infestation
Early instar caterpillars will typically eat the underside of the leaf creating “windowpanes”. In contrast, the late instar caterpillars will eat the entire leaf, leaving the midrib or the outline (skeletonized leaves). It is not until sufficient feeding damage by late instar caterpillars will infestations be more noticeable. As the caterpillars eat, they also produce a silk webbing around the branches and between leaves. The webbed leaves act as protective coverings while they eat or as an overwintering structure. Webbing may also be produced by nesting spiders so that alone is not a good indicator. Green-black frass is also another indicator which can be found on top of the webbing or on the crook of the branches. Early detection may not always be possible, as caterpillars spin leaves together to create cover and will generally hide within the shrub.
Repeated and continuous infestations reduce the shrub’s chances of recovery. Once the shrub is completely defoliated, the caterpillars begin to feed on the bark. This can girdle the shrub, potentially killing the shrub.
Lookalikes
Adults of the melonworm moth (Diaphania hyalinata), appear similar to BTM adults. However, it does not have the crescent markings on its forewings. It also primarily feeds on cucurbits, not boxwoods.
Caterpillars of the euonymus leaf notcher (Pryeria sinica) and euonymus caterpillar (Yponomeuta cagnagella) have similar markings, and show feeding damage similar to box tree moth caterpillars. Another similarity is that they gregariously defoliate leaves while leaving webbing and frass on the stems of the shrubs. However, the caterpillars are generally only active during the springtime and feed on euonymus (burning bush, spindle tree etc..) NOT on boxwoods.
There are other pests and disease that can cause a boxwood to look sickly and bare but they generally do not involve whole skeletonized leaves. The University of Maryland Extension has a helpful guide in identifying and managing common boxwood problems.
Management
The Maryland Department of Agriculture does not have the resources to do residential treatments.
Below are methods that can help manage infestations. But make sure you are certain it is box tree moth before applying control measures to your boxwoods. Also, if you are moving or buying boxwoods please inspect them first for any signs of box tree moth to help prevent its further spread.
Manual removal of box tree moth and any of its life stages on the plant is an easy option, though labor-intensive depending on the infestation level. Make sure to check the interior of the boxwood and the underside of leaves for any hidden caterpillars.
If it is heavily infested, either pruning infested branches, or cutting the whole boxwood down to its base is recommended. However, caterpillars are able to pupate and overwinter outside the plant, so the debris around the ground should also be removed. Any infested clippings, parts or debris should be double-bagged for disposal to prevent further spread.
There are currently no pesticides that exclusively kill box tree moth and preventative sprays on boxwoods are not recommended. Some pesticides also require pesticide license to be applied and should only be used by professionals. Chemical treatments need adequate coverage to penetrate the interior of the boxwoods and the caterpillar webbing. Improper use of pesticides may also cause secondary pest outbreaks like mites and other non-target effects on beneficial insects and the environment.
For information about your chemical options, you can contact your local Extension office for recommendations and further actions. Additionally, Cornell Extension and Penn State Extension provide some additional management options and both list chemical options for homeowner and commercial use. However, these are state specific and the active ingredients listed might not be available or legal to use in Maryland.
Quarantine
As of August 2026, eight counties are under a quarantine for BTM: Allegany, Caroline, Cecil, Frederick, Garrett, Kent, Queen Anne's and Washington county. It is still a good idea to be on the lookout for BTM across Maryland, not just in the quarantined counties.
The Quarantine Order - PDF - 746.49 KB prohibits the movement of Regulated Articles from and within the quarantine zone. Businesses involved with growing and shipping boxwoods must sign a Compliance Agreement with the Department and then obtain a certificate of inspection to ship boxwoods.
Regulated Articles include:
- Any life stage of Box Tree Moth (Cydalima perspectalis) dead or alive.
- The Buxus genus including: cultivars, varieties, plant parts and debris.
- Any other articles, with reasonable doubt, that may present the risk of spread or is susceptible to infestation.
Persons found to have violated the order are liable for civil penalties. If you have any questions about the quarantine contact us at [email protected].
Resources
- USDA BTM Federal Quarantine Viewer
- USDA Website
- USDA Pest Alert - PDF
- USDA Pest Response Guideline - PDF
- Flickr: USDA Pictures
- Video: USDA Checking Your Boxwoods
- UMD Extension