Updated for the 2026 season
Don't replace your box hedge.
Box tree caterpillar strips a mature hedge in under a week. It is also one of the few garden pests with a cheap treatment that genuinely works and is harmless to bees. Here is exactly what to buy and what to do with it.
The whole treatment, in three steps
Check it really is caterpillar
Part the foliage and look inside. Fine white webbing and tiny green-brown pellets mean caterpillar. Brown spots and black stem streaks with no webbing mean blight, which needs a completely different approach.
Pick off what you can, then spray Bt
Drop the big ones in soapy water. Then mix one 3 g sachet into 3 litres, add a drop of washing-up liquid so it sticks to the waxy leaves, and spray in the evening until it drips from inside the plant. Repeat after 7–10 days. Full instructions →
Feed it, and watch for the next generation
Scratch a stem — green under the bark means it will come back. Feed in spring and midsummer. Hang a trap in April so the next generation does not catch you out. Timing guide →
Start where you are
Most people arrive here with one of four problems.
Something is eating my box
Webbing, green droppings, leaves stripped to a skeleton. Seven signs to check, with photographs of each.
Identify itI know what it is — what do I buy?
Everything compared since 2019, and the three products that actually matter.
What to buyWhen am I supposed to spray?
Timing decides whether Bt works at all. The UK calendar, generation by generation, and how to spot the start of one.
Timing guideIt's already stripped bare
Scratch the bark. Green underneath means it lives. The rescue routine and a realistic recovery timeline.
Rescue itWhat I use, and why
I have had box tree caterpillar in my garden in New Malden every year since 2019, including one season where the hedge was stripped to bare stems and took two years to come back. Three products have earned their place in that time. Everything else I have tried is either optional or a waste of money.
TOPBUXUS ABC — Anti Box Tree Caterpillar
15 g treats 150 m² · 5 × 3 g sachets
The current TOPBUXUS Bacillus thuringiensis product and the direct replacement for the XenTari sachets UK gardeners have used for years. Caterpillars stop feeding within about an hour and die within a few days.
What works
- Stops feeding within about an hour
- Completely safe for bees, birds, pets and children
- Five separate 3 g sachets — no waste, no scales needed
- Three-year shelf life, so a box lasts several seasons
What to watch
- Only works if the spray reaches inside the plant
- Needs re-applying every 7–10 days during an active generation
- Degrades in UV — has to go on in the evening
TOPBUXUS Box Tree Moth Trap
Delta trap + 2 pheromone lures — a full season
A pheromone trap will not clear an infestation, but it tells you exactly when the moths are flying. Covers up to 200 m². Two lures included: one in mid-April, the second in mid-July.
What works
- Removes the guesswork from spray timing
- Two lures cover a whole season
- Covers up to 200 m² — enough for most gardens
- Reusable body; only the lures need replacing
What to watch
- Will not control an infestation on its own
- Catches males only
- Needs hanging by mid-April to be useful
TOPBUXUS GROW
500 g treats 10 m² · also 5 kg and 20 kg
Slow-release granular root feed formulated for Buxus, with the magnesium that keeps box deep green. Apply March–April and again June–July while a damaged hedge is regrowing.
Other sizes: 5 kg (100 m²) · 20 kg (400 m²)
What works
- Formulated for box rather than generic hedging
- Magnesium prevents the yellowing you get from general feeds
- Slow release — two applications cover the season
What to watch
- Granular, so it needs watering in during a dry spring
- The 500 g pack only covers 10 m²
See everything compared, including blight treatment and sprayers →
If you are looking for XenTari
For years the standard advice — including mine — was "buy TOPBUXUS XenTari". Those listings have gone. The same manufacturer now sells the same Bacillus thuringiensis sachets as TOPBUXUS ABC: identical 3 g sachets, identical dose of one sachet per 30 m², identical active ingredient. If you have been searching for XenTari and hitting dead pages, ABC is what you want. The full story →
Every guide on this site
Written from one garden, one pest, every season since 2019.
Complete treatment guide
Every method, step by step, with mixing rates and spray technique.
ReadXenTari review
Does Bt work? Mixing, spraying, safety and what goes wrong.
ReadABC vs XenTari
Same product, new name. What actually changed.
ReadPheromone traps
Worth buying — but not for the reason most people think.
ReadXenTari vs nematodes
Both biological. Only one is reliable.
ReadHealth-Mix for blight
A feed, not a fungicide — and why that distinction matters.
ReadFeeding box
What to feed, when, and why general fertiliser causes blight.
ReadUK regional guide
Which areas are worst hit, and when it reached yours.
ReadAlternatives to box
Six pest-resistant substitutes, and how to switch.
Read