Common name
Box Tree Moth, Box Tree Pyralid
Order: Lepidoptera (moths and butterflies)
Family: Crambidae (crambid snout moths)
History & Introduction
Box tree moth (BTM) is native to East Asia’s temperate and sub tropical regions and has rapidly spread throughout the Western Asia, Northern Africa and was first introduced in Europe in 2007. Box tree moths were first detected in North America in Ontario, Canada in November 2018 and were later confirmed in Niagara County, New York in July 2021. It is believed that the moths flew or were blown into the United States. Box tree moths are considered to be very mobile and are good fliers. The natural spread of this moth in Europe is about 3 to 6 miles per year. BTM’s long-distance movement across Europe has been due to the movement of infested nursery stock. Multiple detections have been made at nurseries where boxwoods are commonly grown and shipped. DNA evidence supports that BTM were initially introduced into Europe from Asia and moved within Europe via nursery trade after they were introduced.
Identification & Life Cycle
Box tree moth’s morphology varies throughout its life cycle. However, it has the greatest ecological impact in its caterpillar phase.
Eggs: Adult female box tree moths lay their eggs in clusters in a gelatinous mass on the underside of boxwood leaves. BTM eggs are pale yellow, averaging 0.004 inches that are laid in flat groups of 5–20 and overlapping resembling shingles. Eggs take three days to develop, and when the young caterpillars are close to hatching, the head capsule becomes visible through the egg. Box tree moths can have 1–5 generations per year depending on the latitude and local climate. BTM will overwinter as larvae and can survive temperatures to at least -22°F (-30°C).
Caterpillars : Once temperatures rise to 46–53°F, overwintering larvae emerge and begin feeding in March, continuing until they pupate in late April to early May. BTM caterpillars are about 1.6 inches long and are green and yellow with white, yellow, and black stripes and black spots. As they develop, they spin silken webs that hold leaves together and create protected areas to feed. They feed on leaves in the lower portion of host plants but reside in the upper portion and remain active until September or October.
Pupae: Pupation develops inside a silk cocoon and are 0.6 to 0.8 inches long. They are initially green, with black stripes on the back, and turn brown as they mature.
Usually occurring on the host leaves in silk cocoons. Pupae will typically first appear in April or May and will be present continuously through the summer and into the fall.
Adults: Adults first emerge from the overwintering generation between April and July, depending on climate and temperature. Subsequent generations are active between June and October. BTM can have 1-5 generations within the year if local conditions allow. Adults typically live for 2 weeks after emergence. Adult box tree moths generally have white bodies with a brown head and abdomen. Their wings are white and slightly iridescent, with an irregular thick brown border spanning 1.6 to 1.8 inches. Some adults have completely brown wings with a small white streak on each forewing. Males and females show both colorations.
Similar species: Adult box tree moths may be confused with the melonworm, Diaphania hyalinata, which is found in the United States in south Florida and possibly south Texas. This melonworm feeds on the leaves of cucurbits. It has similar morphology in the adult stage.
Damage and Concerns
- Host: The BTM completes its development and causes extensive damage mainly on boxwood (Buxus) species
- Buxus microphylla – littleleaf boxwood,
- Buxus microphylla var. japonica – Japanese boxwood,
- Buxus sinica var. insularis – Korean boxwood
Signs of damage may not appear at the beginning of an infestation because young larvae hide among twigs and leaves. Caterpillars feed primarily on the boxwoods (Buxus spp.) leaves and defoliate host plants, causing serious plant decline and death when infestations are heavy. Plant symptoms can include green-black frass and visible webbing/silk threads on the host plant. BTM larvae have also been observed moving to bark feeding after the host plants’ leaves are gone, causing girdling and eventually plant death.
Financial concerns: BTM feeds on boxwoods, which are an important part of the United States nursery industry, with annual wholesale and retail sales estimated at a value of $140 million. They are typically known for being low maintenance, deer resistant hedges, and are a favorite shrub for landscaping projects. Movement of boxwood (Buxus) species into the United States is being regulated federally by the United States Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS).
Monitoring and Reporting
Box tree moths is a Tier M species in the LIISMA region. At this point the recommendation is to bag the infested plant material, safeguard it on site and contact the New York State Department of Agriculture and Markets through their Box Tree Moth Public Report portal for additional advice. We also urge you to please report any sightings of the plant to iMapInvasives or iNaturalist Your observations are key to our mission, as they allow us to respond to emerging populations before becoming a larger threat to New York.
iMapInvasive is a network for invasive species reporting, allowing concerned parties like LIISMA to verify where invasive species may be popping up, or their geographic extent. Similarly, iNaturalist functions as a biodiversity reporting platform for all kinds of living things, native or non-native; and can help anyone identify and share what species are inhabiting a given area.
NYS Department of Agriculture and Markets has started surveying in high-risk areas in Niagara County for BTM after the initial findings in 2021 and have also found BTM larvae in a residential landscape in Youngstown, New York. Findings were confirmed by Cornell University and the USDA National Identification Services. Since the initial detection, the Department and APHIS have continued to survey for BTM with finds in Erie, Orleans, Monroe, Wayne, Cayuga, and Oswego Counties. We request that residents and the horticulture industry also look for, take pictures of, and report any signs of infestation to agriculture.ny.gov/reportBTM.
NYSAGM and USDA APHIS have placed quarantines to prevent the spread of invasive species into new areas. The Department established an intrastate quarantine to restrict the movement of boxwoods within the state. Regulated articles include the whole plant, all plant parts, pieces, cuttings, clippings, debris, and any portion of the plant, alive or dead. This quarantine also requires the prenotification of all boxwood plants shipped from quarantine areas both within New York as well as from quarantined areas outside of New York. Boxwood Prenotification Tool.
On May 22, 2024, USDA amended its Federal Order to update the box tree moth quarantine area and establish conditions for interstate movement of regulated articles of boxwood from quarantined areas. Any signs of infestation, please take a picture and report it online at agriculture.ny.gov/reportBTM.
Sources
Box tree moth. Agriculture and Markets. https://agriculture.ny.gov/plant-industry/box-tree-moth
Box tree moth. CALS. https://cals.cornell.edu/integrated-pest-management/outreach-education/fact-sheets/box-tree-moth
Cook, J. C., Culliney, T., Funaro, C. F., & van Kretschmar, J. B. (2022, February 22). New Pest response guidelines cydalima perspectalis box tree moth. https://www.aphis.usda.gov/sites/default/files/box-tree-moth-nprg.pdf
Pest alert: Box tree moth. (2025, February). https://www.aphis.usda.gov/sites/default/files/alert-box-tree-moth.pdf
Skvarla, M. J. (2023). Box tree moth is an invasive pest that has decimated wild and. https://www.pa.gov/content/dam/copapwp-pagov/en/pda/documents/plants_land_water/plantindustry/plant-protection/box-tree-moth/documents/Penn%20State%20Extension%20Box%20Tree%20Moth%20Fact%20Sheet.pdf
