Box Tree Moth in Ontario: What’s Happening to Your Boxwoods and How to Respond

Boxwood hedges across Ontario are turning brown — discover what’s behind the decline. Learn how the Box Tree Moth is affecting gardens, how to identify early signs, and which alternative plants Horvath Landscapes recommends for long-term protection.

Junning Wang

Landscape Designer, Horvath Landscapes Inc.

Visible signs of Box Tree Moth infestation.

The Real Culprit Behind Ontario’s Boxwood Decline

Earlier this year, a residential garden in London, Ontario saw its boxwood hedges mysteriously turn brown and defoliate within just a few weeks. Similar incidents have since been reported across Ontario, where homeowners and landscapers are now facing the same growing concern.

Boxwood (Buxus spp.), known for its evergreen foliage, easy pruning, and strong structural form, has long been one of the most trusted and widely used shrubs in both Ontario’s residential gardens and landscapes around the world.However, an invasive pest — the Box Tree Moth (Cydalima perspectalis) — is rapidly changing that reality.

Once a timeless symbol of structure and elegance, boxwood is now facing an unprecedented threat. This outbreak is forcing both homeowners and garden professionals to reconsider how boxwood can be protected — or even replaced — in modern garden design.

Who is the Real Culprit?

The Box Tree Moth (Cydalima perspectalis) originated in East Asia and was first identified in Europe in 2007. It made its way to Canada in 2018, when it was detected in the Greater Toronto Area. Over the past decade, this pest has spread across continents as an aggressive invader. Reports of new outbreaks appear almost every year in different parts of Europe and North America.

Box Tree Moth’s New Target: Boxwood ‘Green Velvet’

The larvae feed on boxwood leaves and bark, quickly defoliating and weakening the plant. Within a short period, severe infestations can cause complete dieback and even total plant loss.

Signs of Infestation & What to Do

If your boxwoods show signs of damage early in the summer — such as chewed leaves, webbing, or browning foliage — there’s a chance they may have been affected by the Box Tree Moth.

1. Visit the official Canadian Food Inspection Agency (CFIA) website and review the Plant Pest Cards for identification details.

   
   

2. If you find caterpillars actively feeding on the shrubs, apply BTK spray. Check again in 5–7 days and reapply if necessary. BTK works best when applied three to four times per year during the active feeding season. When removing infested clippings or shrubs, place them in a black plastic bag, tie it tightly, and leave it in direct sunlight for 48 hours before disposing in yard waste bins. This helps prevent the larvae from spreading.

   
   

3. Given the increasing severity of Box Tree Moth infestations across Ontario, consider exploring alternative plant species that offer similar structure and year-round greenery.

Plant Alternatives Recommended by Horvath Landscapes

If your boxwoods have reached the point where recovery is no longer possible, Horvath Landscapes recommends several reliable alternatives that can preserve the same structure and greenery in your garden.

Shamrock Inkberry Holly

• For smaller formal hedges — such as those typically made with Boxwood ‘Green Velvet’ — consider using Inkberry (Ilex glabra) or Barberry (Berberis spp.). These plants offer dense foliage, are easy to shape, and provide strong year-round color.

  
  

• For larger rounded forms, Globe Cedar (Thuja occidentalis ‘Danica’ or ‘Woodwardii’) is an excellent substitute.

  
  

• For taller, upright designs — often created with Boxwood ‘Green Mountain’ — species like Hicks Yew (Taxus x media ‘Hicksii’) or certain Junipers (Juniperus spp.) can be great alternatives, offering a similar vertical structure with improved hardiness.

In many of our recent projects, Inkberry has become a preferred replacement for Boxwood ‘Green Velvet’ hedges due to its natural shape, evergreen texture, and adaptability to Ontario’s climate.

Need Help with Your Boxwood?

If your boxwoods are showing signs of decline and you’re considering replacement, contact us today — we guarantee a response within 24 hours.

Horvath Landscapes Inc. is a full-service landscape design and build company specializing in planting design, interlock paving, lighting, and outdoor living spaces. We proudly serve York Region, Toronto, and North York, providing creative and sustainable landscape solutions tailored to every home.