Boxwoods are a staple in many Ontario landscapes, valued for their versatility and year-round greenery. However, if you’re noticing that your boxwood shrubs aren’t looking as healthy as usual this year, you might be dealing with the box tree moth—a pest that has recently become a major issue in Ontario.

Understanding the Threat: Box Tree Moth

The box tree moth spreads mainly through the movement of infested boxwood shrubs, but it can also fly an estimated 5-10 kilometers per year. Ontario was declared an infested area in 2023, and now this destructive pest is spreading rapidly, particularly between Toronto and Windsor, as well as Toronto and Niagara.

How to Spot the Infestation

Early detection is key to saving your boxwoods. Here’s what to look for:

• Defoliation: The most obvious sign is severe defoliation, where the leaves are either partially eaten or missing entirely.
• Webbing: You might notice silk webbing on the shrub, especially around damaged leaves.
• Larvae: The larvae are greenish-yellow with black heads and stripes running lengthwise along their bodies. They are the primary culprits behind the damage.

Recommendations: Save or Replace?

Once a boxwood is infested, the key question is whether it can be saved or needs to be replaced. Here’s what to consider:

1. Assess the Damage: If more than 50% of the shrub is defoliated, it may be too late to save it. In such cases, removal is recommended to prevent further spread to nearby healthy plants.
2. Prune and Treat: For less severe infestations, pruning the affected areas and treating the plant with appropriate insecticides can be effective. Be sure to monitor the plant closely after treatment.
3. Prevent Future Infestations: To protect your boxwoods next season, consider applying preventative insecticides in early spring. Regularly inspect your plants for early signs of infestation, and act quickly if you spot any.

Final Words

At Rock Busters, we typically focus on hardscaping materials, but given the widespread use of boxwoods in landscaping, we want to ensure you have all the information needed to protect your outdoor spaces. Don’t let the box tree moth ruin your beautiful boxwoods—take action now to preserve the health of your landscape.