What is box tree moth caterpillar?
Cydalima perspectalis is a moth whose larvae feed on Buxus foliage. First recorded in the UK in recent decades, it has become a significant garden pest, particularly in formal planting.
Education
Box Tree Caterpillar Guide
A specialist reference for identifying, understanding and monitoring box tree moth caterpillar on box hedging, topiary and formal planting.
How to identify the caterpillar
Bright green with black stripes and black heads, growing up to about 4 cm long. Often found within dense foliage or wrapped in silk webbing.
How to identify the adult moth
Typically white with a dark brown border, wingspan around 4 cm. A dark form also exists.
Common signs of infestation
Skeletonised leaves, webbing between leaves and stems, frass (droppings) within foliage and rapid browning of hedges or topiary.
What webbing looks like
Fine silk threads binding leaves and stems, often concealing caterpillars and their frass inside dense growth.
How quickly damage can spread
Multiple generations per year and rapid feeding mean untreated infestations can defoliate valuable plants within weeks.
When to inspect box plants
Regularly through spring, summer and early autumn. Focus inspections after warm periods and known flight events.
How to inspect dense hedging
Part outer growth to look inside the plant. Check top, sides and interior. Look for webbing, frass and live caterpillars.
When treatment may be required
As soon as active caterpillars, webbing or fresh damage is confirmed. Follow the authorised product label for timing.
How to prevent severe damage
Combine early identification, timely treatment, monitoring and healthy plant husbandry.
Caterpillar and damage photographyFinal photography to be supplied
Box foliage and inspection photographyFinal photography to be supplied
Box tree caterpillar
- Chewing damage
- Webbing between leaves
- Visible green-and-black caterpillars
- Leaf loss and skeletonisation
- Frass and debris within foliage
Box blight
- Leaf spotting
- Dark stem lesions
- Fungal symptoms
- Leaf fall without caterpillar webbing
This guide is for general identification purposes and does not replace professional diagnosis.
Frequently asked questions
Adults typically fly between spring and early autumn, with multiple generations per year.
In many cases, established plants can recover with correct care, monitoring and follow-up treatment where appropriate.
No. Box blight is a fungal disease. Caterpillar damage is caused by larvae feeding on foliage.
During the active season, inspect at least fortnightly and after warm spells.