Boxwoods are a beloved feature in many landscapes, known for their lush greenery and versatile shapes. However, if you’re a boxwood owner in Michigan, your shrubs may be in danger. The invasive box tree moth (Cydalima perspectalis), native to East Asia, has emerged as a significant threat, rapidly spreading across Michigan and causing devastation to boxwood plants.
Here’s what you need to know about this invasive pest, the damage it causes, and how you can protect your shrubs.
What is the Box Tree Moth?
First detected in North America in 2018 in Toronto, Canada, the box tree moth reached Michigan in 2021, likely through infested nursery stock. This small insect with a wingspan of about 1.5 inches can be identified by its white wings bordered with dark brown. Some moths, however, may appear entirely brown with distinct white comma-shaped spots on their forewings.
The true culprits of destruction are the larvae—lime green caterpillars with black stripes and tiny white spots. These caterpillars feed voraciously on boxwood leaves and bark, leaving significant damage in their wake.
Why Are Box Tree Moths Dangerous?
The box tree moth poses a severe risk to boxwood shrubs for several reasons:
- Rapid Defoliation: The caterpillars can strip a shrub of its foliage within a single season.
- Complete Plant Death: After consuming the leaves, they move on to bark, leading to girdling that kills the plant.
- No Natural Predators: Without predators in Michigan, their population can grow unchecked, limited only by the availability of boxwoods to feed on.
How to Identify an Infestation
Early detection is key to protecting your boxwoods. Look out for these signs of a box tree moth infestation:
- Yellowing Leaves: This is often the first visible sign of damage.
- Caterpillars: Look for lime green caterpillars with black stripes, shiny black heads, and small white spots.
- Webbing: Loose silk-like webbing may be seen within the shrub.
- Frass (Caterpillar Droppings): Tiny green balls can be found in the webbing, on leaves, and on the ground beneath the plant.
- Skeletonized Leaves: The foliage may appear chewed up, with only the midrib remaining.
Adult moths are most active from June to October, so be particularly vigilant during this time.
What to Do If Your Boxwoods Are Infested
If you suspect your boxwoods have been infested, it’s crucial to act quickly:
- Manual Removal:
- Hand-pick caterpillars off the plant.
- Use a strong stream of water to knock them off.
- Apply Pesticides:
- Spray with insecticides labeled for moth control, such as bifenthrin or pyrethroid-based products.
- Timing is critical—apply pesticides in late July and again in early September to target the caterpillars’ active stages.
- Contact Professionals: If unsure about treating the infestation yourself, consult a landscaping or pest management professional.
- Follow Quarantine Guidelines: If you’re in one of the 12 quarantined counties (Livingston, Wayne, Oakland, and more), refrain from moving boxwood plants or materials outside the regulated area to prevent further spread.
Preventative Measures
Protecting your boxwoods from infestation is always better than reacting to one. Here are some preventative steps you can take:
- Inspect New Plants: Check for larvae, eggs, or damaged foliage when purchasing boxwood plants from nurseries.
- Regular Monitoring: Frequently examine your shrubs for signs of infestation, particularly during the active months of June to October.
- Precautionary Spraying:
- Nursery growers and homeowners can apply a Bacillus thuringiensis (Bt) product targeting caterpillars.
- Use the recommended strain kurstaki for effective results.
Why Acting Quickly Is Important
Neglecting to address a box tree moth infestation can result in the complete loss of your boxwood shrubs, which are often valuable investments in both monetary and aesthetic terms. Furthermore, unchecked infestations can allow the moths to spread to nearby properties, causing more extensive damage.
How Fischer Landscapes Can Help?
At Fischer Landscapes, we understand the importance of keeping your garden healthy and free from invasive pests. Our expert landscaping team offers pest monitoring and treatment services, ensuring your boxwoods stay vibrant and safe. Whether you need guidance about pesticide applications or want professional maintenance to protect your investments, we’re here to help.
Contact us today to learn more about safeguarding your shrubs from the box tree moth and other invasive threats. Together, we can keep your landscape beautiful and thriving.
Stay Alert, Stay Prepared
The box tree moth is a fast-moving and destructive pest, but with vigilance and swift action, its impact can be minimized. Regularly inspect your shrubs, follow treatment recommendations, and don’t hesitate to call in experts when needed. By working together, we can help Michigan’s landscapes stay lush and green for future generations.
