Box tree moth: how do you fight it — and what should replace box?
By Hovenier Hoofddorp · Updated July 19, 2026
Box (Buxus) turning brown and bare in weeks is almost always the box tree moth: green-and-black caterpillars strip the leaves, leaving webbing and green droppings. You have three options: treat biologically (effective but yearly work), cut back hard and protect, or replace box permanently with a resistant look-alike — which is what we recommend in most gardens.
How do you recognise and treat the infestation?
- Signs: bare twigs with only leaf veins (damage starts inside the plant), webbing with green droppings, caterpillars up to 4 cm.
- Cut out visible webbing and caterpillars; dispose in the green bin, not the compost heap.
- Spray with Bacillus thuringiensis (a biological caterpillar treatment, sold as Xentari and similar): kills young caterpillars, spares bees. Repeat per generation — two to three times a season (roughly May, July, September).
- Pheromone traps from May show exactly when a new flight starts, so you time the spray right.
A stripped box is rarely dead: cut back hard, feed and water, and it usually re-shoots. But the moth returns every year — factor in permanent maintenance, or replace.
What are the best box alternatives?
| Alternative | Box look-alike? | Notes |
|---|---|---|
| Ilex crenata (Japanese holly) | Closest match | Wants well-drained, slightly acidic soil |
| Euonymus 'Green Spire' | Strong | Tough, faster, handles clay well — our default advice here |
| Yew (Taxus) | Darker, finer | Ideal for low and tall formal hedging; poisonous |
| Lonicera nitida | Reasonable | Very fast and cheap, needs frequent trimming |
On the clay of this region we usually plant Euonymus or yew. We replace complete box hedges including removal of the old plants — see our planting plan.
What does replacing a box hedge cost?
Removing the old hedge and planting the alternative costs roughly €25–€70 per metre, depending on the replacement species and size. Compare that with yearly spraying rounds plus the risk of losing the hedge anyway — for most gardens replacement pays for itself within a few seasons. Birds increasingly help too: great tits have discovered the caterpillar, so a bird-friendly garden (nest boxes, no broad-spectrum pesticides) is part of the solution.
Frequently Asked Questions
Is my brown box hedge dead?
Usually not. Cut back the damaged parts hard, remove caterpillars and webbing, treat with Bacillus thuringiensis, then feed and water — box often re-shoots from old wood. Check it is not box blight (dark leaf spots, leaf drop) instead, which needs a different approach.
When should you spray against box tree moth?
When young caterpillars are active: typically April/May, July and sometimes September. Pheromone traps show each flight; spray about two weeks after a flight peak for maximum effect.
Will the moth attack my new Ilex or Euonymus?
No — the box tree moth feeds exclusively on Buxus. All the alternatives named here are immune to it, which is precisely why replacement is the only permanent solution.
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