Image by iredding01, Adobe Stock

Box Tree Moth Typical Form

Image by Courtesy of Ilya Mityushev, Department of Plant protection of the Russian State Agrarian University - Moscow Timiryazev Agricultural Academy

Box Tree Moth Dark Form

Image by Walter Schon

Eggs

Image by Ilya Mityushev, Department of Plant protection of the Russian State Agrarian University - Moscow Timiryazev Agricultural Academy

Pupae

Image by Courtesy of Matteo Maspero and Andrea Tantardini, Centro MiRT - Fondazione Minoprio [IT]

Image by Lavizzara, Adobe Stock

Box Tree Moth Damage

Box Tree Moth

Courtesy: Matteo Maspero and Andrea Tantardini, Centro MiRT - Fondazione Minoprio [IT]

** Reports of caterpillars active in our area (northern Erie County) as of early May 2024 - Check your Boxwoods.

Box Tree Moth (BTM) is an emerging North American invasive species impacting Buxus spp..

Background

Boxwoods are popular shrubs. These plants make an excellent choice for hedges and topiaries and are considered deer-resistant. Older boxwoods may hold historical value. Many states have historical gardens containing boxwoods, which BTM could devastate.

BTM is native to East Asia. The first detection in North America was in Toronto, Canada in 2018 via a citizen report to iNaturalist. The first report in New York State was made in 2022 in Niagara County (across the Niagara River from Ontario, Canada). As of early 2024, the moth has been identified in seven counties in New York State mainly along Lake Ontario. There are also detections in MI, OH, and MA. Since its introduction to Europe in 2006, it has become a serious invasive pest on that continent, where several Buxus spp. are native. 

The caterpillars feed mostly on boxwood, and heavy infestations can defoliate host plants. Once the leaves are gone, larvae consume the bark, leading to girdling and plant death. Inspect your plants for signs of the moth. If your county does not have a known infestation of BTM, report your findings.  See the reporting link to the left.

Insect Biology

(See photos of insect life stages in banner slideshow.)

Female moths lay eggs singly or in clusters of 5 to more than 20 eggs in a gelatinous mass on the underside of boxwood leaves. Most females deposit more than 42 egg masses in their lifetime. Eggs typically hatch within 4 to 6 days.

BTM overwinter as 2nd or 3rd instar caterpillars.  Pupae first appear in April or May and can be found continuously throughout the summer and into the fall, depending on the local climate and timing of generations. After the earliest pupation phase, adults emerge between April and July, depending on climate and temperature. Subsequent generations are active between June and October. Adults typically live for two weeks after emergence.  Researchers are finding there are two generations per year in western New York.

BTM are highly mobile and are reported to be good fliers. In Europe, moths have been found to spread about 3 to 6 miles per year. One analysis from Europe concluded that natural dispersal from continental Europe to the United Kingdom was possible, suggesting sustained adult flights of over 20 miles. Adult moth wingspan is 1.5 to 1.75 inches.

Information on Possible Look-alikes

Links to More Information

   New York State Agriculture and Markets

   NYS IPM BTM information

   Penn State Extension

   USDA Animal Plant Health Inspection Service (USDA APHIS)

   Pest Response Guidelines (USDA APHIS)

   New York State Quarantine Info (NYS Ag and Markets)

General questions?

Contact your county agriculture or horticulture Extension Educator or Brian Eshenaur or Jacob Leeser at NYS IPM.

Last updated May 16, 2024