Box Tree Moth: Management Guide

This invasive species has become a serious pest in many regions outside its native range, including Europe and North America, where it lacks natural predators and can rapidly proliferate. Initially detected in North America in Toronto, Canada, the box tree moth (Cydalima perspectalis) was first found in the United States in 2021 in New York State. Confirmed sightings have extended its presence to additional states, including Connecticut (2021), South Carolina (2021), Michigan (2022), Ohio (2023), Massachusetts (2023), Delaware (2024), Maryland (2025), and West Virginia (2025). Box tree moth was confirmed in Erie County, Pennsylvania, in 2024. For the latest information on box tree moth identification and spread, please refer to Dr. Michael Skvarla's article, Box Tree Moth.

Management

To effectively manage the box tree moth and mitigate its impact on boxwood populations, a combination of cultural, biological, and chemical control methods, in an Integrated Pest Management plan is recommended. While boxwood holds significant ornamental value in landscaping, severe or recurrent infestations may necessitate more drastic measures. In such instances, it may be advisable to replace heavily affected boxwood with alternative species that offer similar aesthetic appeal and resilience against pests. Suitable alternatives include holly or thuja, which can serve as viable replacements while minimizing the risk of future infestations.

Cultural Control

Infested boxwood plants should be promptly removed and carefully destroyed to prevent the pest from spreading further. Handpicking or pruning affected branches can be effective when infestations are localized and manageable. Regular monitoring is essential to detect any signs of box tree moth activity, including the presence of insects or eggs. Early detection allows for swift intervention, preventing infestations from escalating and causing widespread damage to boxwood populations.

Biological Control

While host-specific biological control agents for the box tree moth are still under study and not yet available for widespread release, there are effective alternatives for managing infestations. Bacillus thuringiensis var. kurstaki (Btk), a commercially available biopesticide, has demonstrated effectiveness against the box tree moth. Btk is widely used in pest management programs and has shown promise in controlling the larvae of various moth species, including the box tree moth. When applied according to label instructions, Btk targets the larvae specifically, minimizing harm to non-target organisms and the environment.

Chemical Control *

There are multiple pesticide options available for controlling the box tree moth. It's important to follow the recommended rates and application intervals specified on each insecticide label to ensure effective and safe usage. Additionally, it's important to prioritize personal safety by wearing appropriate personal protective equipment when handling and applying pesticides. By adhering to these guidelines, you can maximize the efficacy of pest control measures while minimizing risks to human health and the environment.

Homeowners

A commercially available sex pheromone trap can be a valuable tool for early detection and management of the box tree moth. These traps are designed to attract male moths by releasing synthetic versions of female moth pheromones. By monitoring trap catches regularly, especially during periods of moth activity, you can detect the presence of box tree moths in the area at an early stage. This early detection allows for timely intervention when populations are low, helping to prevent infestations from escalating and causing significant damage to boxwood plants.

Several over-the-counter insecticides labeled for caterpillars can be effective against the box tree moth. However, it's important to be aware that many of these insecticides have a broad spectrum of activity, meaning they can kill not only the targeted pests but also beneficial insects. This includes natural predators and pollinators essential for ecosystem health. Therefore, when using insecticides for box tree moth control, it's essential to exercise caution and consider the potential impacts on non-target organisms. Whenever possible, opt for selective insecticides with minimal harm to beneficial insects, or use targeted application methods to minimize off-target effects.

Insecticides containing the following active ingredients can be used to control caterpillars, including those of the box tree moth: acephate, bifenthrin, carbaryl, cyfluthrin, esfenvalerate, permethrin, pyrethrin, resmethrin, and tetramethrin.

Commercial Use

The following list has been adapted from Frank et al. (2022). Please consult the product label for comprehensive information on each pesticide. 

* The inclusion of these insecticides in this management guide does not imply blanket endorsement. The goal is to provide valuable information that enables commercial growers to make well-informed decisions suited to their individual cultivation methods.

Reporting Box Tree Moth

The box tree moth is a Federally regulated species with limited distribution. If you encounter it in Pennsylvania, please report it.

• Visit a Penn State Extension office close to you.
• Contact the Pennsylvania Department of Agriculture at badbug@pa.gov or 866-253-7189.
• For insect identification, contact Dr. Michael Skvarla at mxs1578@psu.edu or send samples to the Insect Identification Laboratory, Department of Entomology, 501 Agricultural Science & Industries Building, University Park, PA, 16802.

References

Boggs, J. 2023. Box Tree (Boxwood) Moth: New Detection, What to Look For, and Management. Accessed 20 March 2024.

Coyle, D.R., Adams, J., Bullas-Appleton, E., Llewellyn, J., Rimmer, A, Skvarla, M.J., Smith, S.S., Chong, J-H. 2022. Identification and Management of Cydalima perspectalis

(Lepidoptera: Crambidae) in North America. Journal of Integrated Pest Management, 13(1): 24; 1–8.

Frank, S, Gilrein, D., Havers, M., Palmer, C. 2022. Insecticide Options for Box Tree Moth Management. Accessed 18 March 2024.

Lesser, J., Eshenaur, B. 2023. Box Tree Moth (Cydalima perspectalis). Accessed 18 March 2024.

Skvarla, M.J. 2020. Box Tree Moth. Accessed 20 March 2024.

(USDA - APHIS) United States Department of Agriculture – Animal and Plant Health Inspection Service. 2023. Box Tree Moth. Accessed 20 March 2024.