Box tree caterpillars can be responsible for causing severe defoliation of box (Buxus) plants.

The adult moth lays flat and yellow eggs on the underside of the leaves that overlap one another. Once hatched the caterpillars create cobweb-like webbing over their feeding area, and devour the box leaves, they are capable of completely destroying a box plant (Buxus) foliage.

They are normally active between April and October when the weather is warmer.

What are the signs of box caterpillars?

• Faded or brown patches – damage tends to start around the base of the bush and moves upwards.
• White webbing across the foliage.
• On shaking the plant you may see the moths fly out – they have white wings with a brown border, or completely brown wings and are around 4cm across.

How do you get rid of them?

• You can remove the caterpillars by hand if possible (please make sure you use protective gloves and a mask!).
• Try a box tree moth trap – this catches the adult moths, preventing new eggs from being laid on your plant.
• Use ‘nematode biological control for fruit and vegetables’ – nematodes are microscopic creatures, that act as parasites to other insects.
• BugClear Ultra 2 – an organic formula to control box tree caterpillars and aphids.

What is box tree blight?

Box tree blight is a fungal disease of box plants resulting in bare patches, black streaks and diebacks on young stems. Leaves will fall to the ground whereas the caterpillars eat them. This disease develops and spreads more in wet conditions.

How do I treat box blight?

• Dispose of any infected leaves into bags to avoid dropping them around the garden (don’t compost!).
• During dry weather cut back the infected area – make sure to clean all your tools afterward.
• Monitor for new infections.

Buxus with Box Blight (Photo by GAPP)

Why not try using an alternative to box?

A good way to eradicate these common issues is to consider choosing an alternative to box plants. Our suggestions are resilient to box moth and blight damage :

Ilex – a very hardy dense evergreen, that’s easy to grow and shape

Taxus – a slower growing evergreen that clips to a smooth dense surface

Pittosporum – a fast growing, dense evergreen that clips well with shears

Lonicera – sometimes referred to as a box leaved honeysuckle. Hardy and easy to grow