If you've spotted white webbing on your box (Buxus), patches of dieback or noticed the leaves have been devoured you could have a box moth infestation, sometimes known as buxus moth or box hedge moth, Cydalima perspectalis.
What are box tree caterpillars?
Box tree moth (Cydalima perspectalis) is an invasive moth species first seen in Britain in 2008. Its destructive larvae were discovered in gardens in 2011. Box tree moths originated in Asia and are now established in London and the home counties with reported sightings as far north as Scotland.
Symptoms of box tree moth caterpillar infestation
- White webbing strung between leaves
- Patches of dieback (not to be confused with box blight)
- Stripped leaves
- Stripped bark
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How to spot box tree caterpillars
Box tree caterpillar eggs are laid on the underside of box leaves and are yellow and flattish.
Young caterpillars are just over an inch long and a greeny yellow colour with black and white striping.
The older caterpillars protect themselves from predators by building a distinctive pale white tent of webbing when they feed.
In winter the small caterpillars hibernate in an envelope of two box leaves that have been spun together the previous autumn.
The adult moth has white wings edged with brown and is just over an inch wide from wing tip to wing tip.
Find out how to grow and propagate your box to avoid box blight
Adult box tree moth
What plants are at risk?
Box tree caterpillars will completely decimate box (Buxus), stripping the leaves.
What damage can they cause?
The caterpillars eat the foliage and in really bad cases this can defoliate the plant causing dieback.
How to control box tree caterpillars
1. Pick the moth larvae off by hand.
2. Try using a pheromone funnel trap. These cost around £25 from Agralan and can be set from mid March to October.
3. Chemical sprays are best used on the young caterpillar as you need a lot of spraying to penetrate the webbing. Avoid using chemicals when the box is in flower or near flowering plants as it can harm pollinators.
Have you seen box tree caterpillars or moths?
If so please report your findings to the RHS by following this link.
Visit our Pests & Diseases section for more guides to controlling problems in the garden, including what to do about honey fungus, powdery mildew and vine weevils
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