The best Box tree moth killers, compared.
Top pick: BuxTrap box tree moth trap Best value: BuxTrap box tree moth trap – About £16.99 includes four lures, with 4.2 from 146 reviews, and the listing is a moth trap rather than a caterpillar spray. Updated October 2026.
A box tree moth killer is what you search for when green caterpillars strip a box hedge or topiary, leaving webbing, black droppings and bare twigs. The moth, Cydalima perspectalis, does the damage as a larva. The same search returns dilutable powders, ready-to-use sprays and pheromone traps, and those three do different jobs. Match the product to the life stage. Larvae on the leaves need a foliar treatment or hand removal. A funnel trap and a lure refill mainly monitor or catch adult moths, so they sit beside a spray. Brown fungal streaking can be box blight, a different problem. Read the pack for the active, any mix rate, and whether you have a powder, a ready-to-use bottle or a trap. Public UK garden sources describe effective Bacillus thuringiensis kurstaki caterpillar products as professional-only. A marketplace listing is not an authorisation. Check the HSE database for the product name and the ornamental use before you spray. How to separate a powder, a ready-to-use spray and a trap is set out in the [box tree moth killer buying guide](/hub/pest-control/box-tree-moth-killer/sub/box-tree-moth-killer-buying-guide).
A box tree moth killer is what you search for when green caterpillars strip a box hedge or topiary, leaving webbing, black droppings and bare twigs. The moth, Cydalima perspectalis, does the damage as a larva.
26 products checked · 54 hrs invested · +18,600 readers
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Personal buying guide
Question 1 of 2
What are you dealing with?
The BuxusPro BuxTrap is a refillable funnel trap at £16.99 with four pheromone lures, rated 4.2 from 146 amazon.co.uk reviews. The listing says hang it 1–1.5 m above the ground, add 5 cm of water with a drop of detergent, and replace the lure about every six weeks, while also saying each lure lasts 4–6 weeks. Saved reviews report a dozen moths in the first few days, and more than 100 in a week after a quiet start. Buyers who kept the hedge describe the trap used alongside a spray, including XenTari, which is not one of the seven products in this table. Other buyers hung it for a week, saw moths flying, and caught nothing, and several call the plastic flimsy or say the instructions were missing. It catches adult moths and does not kill caterpillars already in the webbing. It is the best value monitoring kit here when a foliar follow-up is already in the plan. It is the wrong buy if you expect the bucket alone to stop defoliation.
Pros
Cons
Best for: You want a reusable trap and four lures under £17, and you will still spray or hand-pick when webbing appears.
Less suitable: You need the caterpillars gone this week, or you have no plan beyond the bucket.
Specifications
Common questions
Does the trap kill caterpillars on the hedge?
No. It targets adult moths for monitoring or catch. Larvae on the foliage need a spray or hand removal.
How often should the lure be replaced?
The listing says about every six weeks, and also that each lure lasts 4 to 6 weeks. Four lures are in the pack.
How is the trap set?
Hang it 1 to 1.5 m above the ground and add about 5 cm of water with a drop of detergent.
Habitat Harvest Buxus Support is another 50 g powder at £13.99, rated 4.2 from 57 amazon.co.uk reviews, and the metadata model line is also BG-CAT50. The listing uses the same 5 g in 2 litres for 30 m² mix and the same 300 m² claim as the other Habitat Harvest powder. Saved reviews say caterpillars had nearly destroyed a hedge and that this pack got rid of them and helped the hedge recover, and one buyer contrasts the price with dearer products used more than once in a year. A separate review says the caterpillars were still there after two weeks and the hedge was full of eggs. The split that matters is this: UK reviews and pack text cite a biofungicide, not a Bacillus thuringiensis caterpillar insecticide. Do not treat this pack as the same buy as the other Habitat Harvest powder. It belongs in the table only so that similar branding does not hide a different active story. It is the wrong powder when the damage is green caterpillars, black frass and webbing and you need a product whose label matches that pest.
Pros
Cons
Best for: You have checked the label and the job on the pack is fungal, not larval.
Less suitable: You are buying it because the title sounds like the other Habitat Harvest caterpillar powder.
Specifications
Common questions
Is this the same powder as the other Habitat Harvest listing?
No. Both use the model line BG-CAT50 and a 50 g pack, but UK reviews and pack text on this listing cite a biofungicide, not a caterpillar insecticide.
How do I mix it?
The listing uses 5 g in 2 litres for about 30 m², and the same 300 m² pack claim as the other Habitat Harvest powder.
Did every review see the caterpillars gone?
No. Some buyers report a hedge recovering. A separate review says caterpillars and eggs were still there after two weeks.
Across 34 amazon.co.uk reviews, the Habitat Harvest 50 g powder (model BG-CAT50) sits at 4.2 and £14.99. The listing says mix 5 g with 2 litres for 30 m², claims up to 300 m² from the pack, and a shelf life of more than three years, and it calls the formula pesticide-free and safe for bees, birds and pets. A saved review credits one application with saving hedges and balls that looked dead. Another says you need to repeat the treatment, especially if it rains, and one buyer followed the packet and reported the hedging brown and dead five days later, so a good average still hides a severe outcome. UK reviews cite Bacillus thuringiensis on the pack, which is not in the listing header. BBC Gardeners' World and EBTS UK describe effective Btk caterpillar products as professional-only, and this comparison does not treat an amazon.co.uk page as HSE authorisation. Check the exact product name before you spray. It is a weak choice if you wanted a spray with no bacterial active, or if you will not repeat it after rain.
Pros
Cons
Best for: You will read the pack active and the HSE database, and you can repeat a spray after rain.
Less suitable: You wanted a pesticide-free spray with nothing bacterial on the label, or a single application before a wet week.
Specifications
Common questions
How do I mix the powder?
The listing says 5 g in 2 litres for about 30 m², and a spoon is supplied. The pack claim is up to 300 m².
Is the formula pesticide-free?
The listing calls it pesticide-free. UK reviews cite Bacillus thuringiensis on the pack, and that active is not in the listing header.
Can it be used on other plants?
Follow the label for approved plants only. Check the exact product name on the HSE database before you spray.
The Green Guard 50 g powder from Gifts by L is the largest review file in this set, at 4.0 from 185 amazon.co.uk reviews and £9.79. The listing tells you to mix 5 g in 2 litres of water for about 30 m², includes a measuring spoon, and claims one pack covers up to 300 m², which it also describes as 20 litres of solution. A saved review describes a pump sprayer on four buxus plants, one of them covered in caterpillars, with none seen two days later. Another gardener sprays a couple of times early in the season and says the caterpillar problem stopped. The same file calls the dilution instructions unreliable, says a stronger mix would not stay affordable on a large hedge, and includes a straight 'did nothing' review. The title also calls it a box blight treatment, and blight is a fungal problem, not the caterpillar. Rain is a reason buyers spray again. It is the top pick here when you want a dilutable powder with a review count you can actually read, and you will check the label and the HSE database before you mix it.
Pros
Cons
Best for: You have enough box to mix a powder, and you will read the label and the HSE database before you spray.
Less suitable: You want a ready-to-use bottle, or you are treating blight rather than caterpillars.
Specifications
Common questions
How do I mix the powder?
The listing says 5 g in 2 litres of water for about 30 m², and a measuring spoon is included. One pack is claimed to cover up to 300 m².
Does the title also say box blight?
Yes. Blight is a fungal problem, not the caterpillar. The title line is a reason the score is marked down.
Can it be used on other plants?
The amazon.co.uk block asks this. Follow the label for approved plants only, and check the product name on the HSE database before you spray.
BuxusPro BuxBarrier is a 500 ml ready-to-use spray at £19.99, rated 4.0 from 16 amazon.co.uk reviews. The listing says the bottle is pre-mixed, Bt-free, and based on a proprietary essential-oil blend, and that you spray it onto affected box. Saved reviews credit it with keeping buxus balls through a summer and with reviving an 18-year-old bush that looked dead, and one buyer says you should water after two or three days. A detailed critical review, from someone who had avoided BT products, says it killed nothing in dry weather even when sprayed straight onto the caterpillars. The page does not state a square-metre rate, unlike the 50 g powders. Sixteen reviews is a thin file next to 185 on the Green Guard powder. It suits a few topiary pieces when you will not mix a powder and you can accept a split result. It is a weak buy for a long hedge if you need a stated coverage figure before you spend £19.99.
Pros
Cons
Best for: You have a few box balls, you want no mixing, and you have read the review that saw no effect.
Less suitable: You need a stated dose for a long hedge, or a large review file before you rely on it.
Specifications
Common questions
Is mixing required?
No. This is a 500 ml ready-to-use spray. Shake if the label says so and spray affected box.
Does the listing say it contains Bt?
The listing says it is Bt-free and based on a proprietary essential-oil blend.
What do the reviews say about kill?
Some saved reviews describe topiary kept through a summer. One review says it killed nothing in dry weather when caterpillars were sprayed directly. The file is 4.0 from 16 reviews, and no coverage rate is stated.
The BuxusPro BuxPhero pack is four pheromone lure refills at £11.99, rated 3.9 from 11 amazon.co.uk reviews. The listing says each lure stays active for up to eight weeks and should be stored below 30 °C in the original packaging, and that you place it in a standard moth trap. A saved review says this style of monitoring works and that refills are needed about every six weeks, which is a shorter interval than the eight-week claim. Another buyer, who had used a paste before, caught one moth and still found the box full of caterpillars. There is no trap body in the pack. Eleven reviews is the smallest sample in the set, so neither the praise nor the failure is a settled pattern. Buy it when a BuxTrap or a similar funnel is already hanging and the old lure has expired. Do not buy it as a caterpillar killer, and do not buy it for clothes or pantry moths.
Pros
Cons
Best for: You already own a box tree moth trap and you are replacing an expired lure.
Less suitable: You have webbing and caterpillars now, or you do not own a trap body.
Specifications
Common questions
Does the pack include a trap?
No. It is four pheromone lure refills for a trap you already own.
How long does a lure last?
The listing says up to eight weeks, stored below 30 °C in the original packaging. A saved review replaces them about every six weeks.
Will the refills clear caterpillars in the hedge?
No. A saved review caught one moth while the box was still full of caterpillars. Larvae on the leaves need a spray or hand removal.
The No More Mr Nice Guy kit is one bucket trap and four pheromone lures at £24.98, rated 3.8 from 14 amazon.co.uk reviews. The listing tells you to place it between March and October, at about one trap per 0.5 acres, to change the lure every five weeks, and to add water to about 3 cm with a dash of washing-up liquid, hung at 1.5–2 m in an open spot near the plants. A saved review calls it fully successful, but fourteen reviews cannot carry the same weight as the BuxusPro trap's 146. The title says caterpillar treatment, and the mechanism is still a pheromone trap for adult moths. At £24.98 it is £8 more than the BuxTrap, which also includes four lures. It fits a large plot where the half-acre density note matches the garden and you will still spray or hand-pick. It is hard to justify for a terrace of two box balls.
Pros
Cons
Best for: You have a large area of box and you want the density and season dates written on the listing.
Less suitable: You have a small town garden, or you need larvae removed from webbing this week.
Specifications
Common questions
Does this trap kill caterpillars on the leaves?
No. It is a pheromone trap for adult moths. The title says caterpillar treatment, but larvae in webbing need a spray or hand removal.
When and how is it set?
The listing says March to October, about one trap per 0.5 acres, a lure change every five weeks, about 3 cm of water with washing-up liquid, hung at 1.5 to 2 m.
Why does the small review file matter?
The line is 3.8 from 14 reviews. One saved review is strongly positive. That sample is too small to carry a badge next to the BuxTrap's 146 reviews.
Seven amazon.co.uk listings are scored from stars, review volume, whether the treatment matches the job buyers describe, and price inside this set. Pantry, clothes and cedar moth products were removed before scoring. There is no laboratory kill test. A high star line from a small file cannot outrank a slightly lower line from a much larger one. Points come off when marketing and the active buyers report on the pack conflict, when a title mentions blight as well as caterpillars, or when a trap is asked to do a spray's job. The top pick is the highest score. Best value is the strongest value among the other products, where the listing's own job is clear and the review file is large. The lowest-priced powder takes the top pick, so the value badge is not given to the same product.
Stars
35%Round of (amazon rating / 5) times 35. Stars are not a kill rate.
Review volume
25%25 points at 150 or more reviews, 22 at 100 or more, 16 at 50 or more, 12 at 20 or more, 8 at 14 to 19, and 6 at 10 to 13.
Job fit
25%Points when the treatment class matches what buyers describe. Deductions when marketing and pack actives conflict, when a title mentions blight as well as caterpillars, or when a trap is asked to do a spray's job.
Value
15%Lower price inside this set, with extra credit when the price includes lures or a large claimed coverage and the review file is not tiny.
Start with the life stage, then the pack, then the label. Green caterpillars, black frass and webbing are box tree caterpillar. Brown streaking may be blight. A powder or a ready-to-use spray is aimed at larvae on the leaves. A pheromone trap monitors adult moths and does not clear webbing on its own. Captured amazon.co.uk prices in this set run from about £9.79 to about £24.98. None of these scores is a laboratory kill test, and none of these listings is treated as HSE-authorised.
A box tree moth killer, in the way the search is used, is a foliar treatment for box tree caterpillar or a pheromone trap sold beside those sprays. The caterpillars of Cydalima perspectalis strip buxus leaves inside webbing and can weaken or kill a hedge after repeated seasons. Signs are green caterpillars, black frass and webbing inside the bush. Brown fungal streaking may be box blight instead. A title that mentions both jobs is not automatically right for both.
Indoor moth products were taken out of this set before scoring. A pheromone for clothes or food moths does not monitor box tree moth, and it does not treat caterpillars in a hedge.
Funnel traps and lure refills catch or monitor adult moths. Caterpillars already in the webbing need a foliar treatment or hand removal. A quiet bucket for a week does not mean the hedge is clear.
One powder listing says pesticide-free while UK reviews cite Bacillus thuringiensis on the pack. Another powder's reviews describe a biofungicide. Read the active buyers report, then check the HSE database for that product name.
Confirm the pest before you pick a pack. Green caterpillars, black frass and webbing inside box are box tree caterpillar signs. Brown fungal streaking may be box blight. The RHS treats those as different problems, and a title that names both is marked down here. Larvae on foliage need a spray or hand removal. In this set that is a 50 g powder you mix, or a 500 ml ready-to-use spray. The powders that state a rate use 5 g in 2 litres for about 30 m².
Read the active story on the pack, not only the title. Two 50 g powders share a 5 g / 2 L / 30 m² instruction, and UK reviews on those caterpillar powders cite Bacillus thuringiensis, which is not in the listing header. A third 50 g powder uses similar branding, and UK reviews cite a biofungicide instead. The ready-to-use spray claims a Bt-free essential-oil blend. Those are different buys.
Three typical situations, each with a recommendation from this comparison.
You have a handful of box balls and you do not want to measure a powder. BuxBarrier is a 500 ml ready-to-use spray at about £19.99, with 4.0 from 16 amazon.co.uk reviews. The listing says the bottle is pre-mixed and Bt-free. Saved reviews describe topiary kept through a summer, and one review saw no kill when caterpillars were sprayed directly. Leave it if you need a stated coverage rate for a long hedge.
You have enough box that a stated mix rate matters. The Green Guard 50 g powder is about £9.79, with 4.0 from 185 reviews. The listing says 5 g in 2 litres for about 30 m², and claims up to 300 m² from the pack. A saved review calls the dilution unreliable, and the title also says box blight. It is the top pick when you will read the label and the HSE database before you mix.
You want to see whether moths are flying, and you will still spray or hand-pick when webbing appears. The BuxTrap is about £16.99 with four lures, rated 4.2 from 146 reviews. It catches adult moths. It does not kill caterpillars already in the hedge. Skip it if the bucket is the only step in the plan.
The top pick is the Green Guard 50 g powder from Gifts by L, at about £9.79. It is the highest score: 4.0 from 185 amazon.co.uk reviews, the largest file in this set, with a stated mix of 5 g in 2 litres for about 30 m². The score is marked down because a saved review calls the dilution unreliable, another says it did nothing, and the title also says box blight. The best value is the BuxusPro BuxTrap at about £16.99, with four lures and 4.2 from 146 reviews. It is a moth trap, not a caterpillar spray, so it does not take the top pick from the powder. None of these scores is a laboratory kill test, and no listing here is treated as HSE-authorised.
BuxTrap box tree moth trap
About £16.99 includes four lures, with 4.2 from 146 reviews, and the listing is a moth trap rather than a caterpillar spray.
Editorial
Peter F. is the editor for DIY & tools at productscompared.co.uk. Comparisons in this category are checked against amazon.co.uk listings, review evidence and public UK sources.
Guides on what to look for, how to use a product, and common mistakes.
Public UK sources used for this comparison. Shelf prices, stars and review counts are the amazon.co.uk figures captured for these seven listings on 20 October 2026. A listing is not treated as HSE authorisation.
This page contains affiliate links to amazon.co.uk. If you buy through them, we may earn a commission at no extra cost to you. Prices, stars and review counts are the UK listing lines captured for these seven products. We did not run a laboratory kill test.
