Box tree caterpillar

Box tree caterpillars feed within webbing and can completely defoliate box plants. It is a relatively new insect to Britain. Whilst the adult moth was first reported in the UK in 2008, caterpillars were not found in private gardens until 2011, it has since become widespread in London and surrounding areas.

Box tree caterpillar

Quick facts

Common name Box tree caterpillar
Scientific name Cydalima perspectalis
Plants affected Box (Buxus)
Main symptoms Foliage is eaten and covered in webbing
Most active April-October

What is box tree caterpillar?

Box tree caterpillars are the larvae of a moth that feeds on box (Buxus) plants. It is native to East Asia and it became established in Europe in 2007. Although adult moths were first found in the UK in light traps in 2008, it was not until 2011 that larvae were reported in private gardens in the home counties. By the end of 2014 the moth had become established in parts of London and surrounding counties; in many cases the caterpillars had caused severe defoliation indicating that the moth is likely to become a serious problem.

Survey

Seen box tree moth? We would like to know.

As part of our research the RHS would like to know where box tree moth has been seen.

Please submit your records via our box tree moth survey (expected time to complete survey = two minutes).

IN 2015 and 2016 over 800 records of the moth were received which indicate that it is now a widespread problem in London and surrounding areas.

 

Thank you to everyone who has submitted records so far – read a blog about the surveys 

Watch an animated map of the results from the box tree caterpillar survey (links to YouTube)

 

The adult moth usually has white wings with a faintly iridescent brown border, although the wings can be completely brown. The moth has a wingspan of around 4cm (1¼in)
Box tree caterpillar distribution
    The adult moth usually has white wings with a faintly iridescent brown border, although the wings can be completely brown. The moth has a wingspan of around 4cm (1¼in) Box tree caterpillar distribution

    Symptoms

    Gardeners are likely to become aware of box tree caterpillar when they find webbing and caterpillars on box plants.

    • The pale yellow flattish eggs are laid sheet-like, overlapping each other on the underside of box leaves
    • Newly hatched caterpillars are greenish-yellow, with black heads. Older caterpillars reach up to 4cm (1¼in) in length and have a greenish/yellow body with thick black and thin white stripes along the length of the body
    • The pupae are concealed in a cocoon of white webbing spun among leaves and twigs
    • The adult moth usually has white wings with a faintly iridescent brown border, although the wings can be completely brown or clear. The moth has a wingspan of around 4cm (1¼in)
    • The caterpillars eat box leaves and produce webbing over their feeding area. Plants may also show patches of dieback which may be especially apparent on trimmed plants. This is not to be confused with dieback caused by the disease known as box blight

    Control

    Non chemical control

    • Where practical, caterpillars should be removed by hand
    • A pheromone trap which can help monitor adult moth activity is available from Agralan
    • The mixed nematode biological control sold as Fruit and Vegetable Protection may have some effect on the larvae

    Chemical control

    • Extensive infestations can be treated with an insecticide. Thorough spray coverage is required if control is to be achieved
    • Forceful spraying is needed to penetrate silk webbing
    • The contact pyrethroid insecticides pyrethrum (considered organic e.g. Bug Clear Gun for Fruit and Veg or Defenders Bug Killer,), deltamethrin (e.g. Bayer Provado Ultimate Fruit & Vegetable Bug Killer, Bayer Sprayday Greenfly Killer), lambda-cyhalothrin (e.g. Westland Resolva Bug Killer) may have some effect.
    • The systemic neonicotinoid insecticide acetamiprid (e.g. Bug Clear Ultra) can also be used
    • Plants in flower should not be sprayed due to the danger to pollinating insects
    • Inclusion of a pesticide product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener

    Do not spray near plants  in flower due to the danger to bees and other pollinating insects

    Downloads

    Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)

    Biological control suppliers (Adobe Acrobat pdf document)

    Biology

    The biology of the box tree caterpillar in the UK is not yet fully known, as it is a recent discovery here, but it may have two or three generations per year. It overwinters as small caterpillars, hidden between box leaves that have been spun together with silk in autumn, and completes its development in spring. The adult moth is capable of flight, but it is not known how far it can travel.

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    • Boxtree

      By Boxtree on 07/08/2014

      I have found box tree caterpillar on a large bush in my Essex garden.spray did not get rid of this and I have resorted to picking off the caterpillars.has any one found a good way of dealing with this pest?


    • Caterina

      By Caterina on 18/08/2014

      Hello. I'm in the south of France, and just discovered that all the box hedges in our garden are infested with this. I was wondering whether "defoliated" in the this case means that the plant itself is _destroyed_ (right now that's how they look!) — or is it just that this year's leaves are temporarily devoured?


    • Mr R  J Cane

      By Mr R J Cane on 18/08/2014

      What birds predate on these varmints ? My advice and experience suggests that we encourage the birds to come and develop a taste for these pests. Their eyesight and little beaks are the best long term way of dealing with most pests. Sprays usually deter predators and lots of "friends". Good hunting !!


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    • Box Tree Moth Fulham SW6

      By Box Tree Moth Fulham SW6 on 09/05/2015

      Hello. There are box tree moth caterpillars all over Fulham SW6 at Parsons Green and running up to the river. Every hedge and plant we have seen has evidence of webs, caterpillars with varying degrees of defoliation. Just to let you know. We have emailed your special address for this also.


    • Mr D C Smith

      By Mr D C Smith on 27/05/2015

      Box tree caterpillars in Chingford (London E4), have tried picking off but am fighting a losing battle.


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    • Mr A Crowther

      By Mr A Crowther on 29/05/2015

      We have a garden of about 1 ha in SW France which has a box parterre grown over the last 10 years, a group of quite old topiary box & 2 small box hedges, all some distance from each other. About a month ago, when the new growth was about 3 to 4 cm long I found about 20 caterpillars on a 1 metre length of hedge. I then found them on every other box in the garden, on 2no box balls in my neighbour's garden and all over another garden with lots of box about 3 kilometers away. I visited a well-known box parterre at Hautefort last week, about 40 km away & could find no evidence of them at all. It was impossible to contemplate removing them all by hand, so we sprayed very thoroughly with 'Bug Clear', which we use for greenfly. It seems to have worked, as they were all dead the following day & I have not found a single live one since. We were lucky that we had just postponed a return to England. If we had left them behind we would have returned to devastation. I am now starting to cut the box & this has revealed extensive damage below the new growth, with dozens of webs. We shall probably spray again in the autumn & go through the plants with a fine tooth comb to try to stop any overwintering.


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    • Hahoo

      By Hahoo on 15/06/2015

      I have a magnificent box hedge around my veg garden planted about 20 years ago. Yesterday I found two box moths and today another. Do the pheromone traps work? Would they be the best thing to use now before the caterpillars appear. I also saw some moths that were completely brown, but failed to catch them. The white moths were stationery on the box leaves and were easy to catch and squash. Inside there was bright yellow material, presumably the eggs. I live in Siena Province, Italy.


    • exile

      By exile on 16/08/2015

      We are in our third year of box tree moth attack. On the advice of the Basel Uni Botanical Dept, we spray all our boxes throughly with Kendo (lamb-cyhalothrin) as soon as we spot an attack and repeat this 3 weeks later. So far, this seems to work but don't mess around with garden centre products or biological controls- you will lose your plants.


    • anonymous

      By anonymous on 18/08/2015

      Hello! I am from Georgia. I have in my garden very old Colchica Buxus trees about 300 years old. They icredible bautiful! These days discovered that our trees are hedges with caterpillars:((((. What will we do??? :(((( Help us!


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    • JDCR

      By JDCR on 20/08/2015

      Just returned to Battersea near the Park from fortnight on holiday to find box hedge has been attacked by this caterpillar which appears to produce copious quantities of small green cous cous-like material. Thanks to this site. I now know what is responsible. Off to get some pesticide.


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    • JDCR

      By JDCR on 20/08/2015

      Just returned to Battersea near the Park from fortnight on holiday to find box hedge has been attacked by this caterpillar which appears to produce copious quantities of small green cous cous-like material. Thanks to this site. I now know what is responsible. Off to get some pesticide.


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    • ianandjennylourmarin@gmail.com

      By ianandjennylourmarin@gmail.com on 20/08/2015

      Here in Provence we have been struggling to deal with this creature for the last five years, and in my opinion the key is frequency of spraying. At that time, the only product which helped was D6, but there are now several reasonably good solutions available. However, unless spraying is carried out every TWO WEEKS, caterpillars reappear and the damage is dramatic and swift. We have lost in excess of 2,000 Euros-worth of plants over the years, so do NOT dismiss this as a temporary irritation.


    • LIB

      By LIB on 26/08/2015

      I am near to Battersea Park too and two 40cm Box Spheres were destroyed in less than 48 hours. I have been determined not to spray and fed the caterpillars to the ducks. After hearing the publicity I am going to spray.


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    • Samlb10

      By Samlb10 on 27/08/2015

      Any guidance on identifying these caterpillars please? I have a plague of VERY similar looking caterpillars currently destroying stocks in my garden in South Devon - could they be box tree caterpillars? Or do they only eat box? Is there are way to tell them apart from other species please?


    • fogey

      By fogey on 29/08/2015

      Saturday in South Woodford E18. Caterpillar damage (to varying degrees) discovered in three gardens this morning. Reluctantly will spray, urgently - seems no other way to overcome the infestation.


    • Paul the Black Sheep

      By Paul the Black Sheep on 30/08/2015

      I felt guilty relief when my neighbour showed me his box hedge caterpillar infestation today (Wormley, Hertfordshire) in the knowledge that I don't have box hedge in my garden! However, within the hour, I happened to notice that the leaves of a horseradish plant in my garden had been decimated, and recognised the same caterpillars as the culprits! These caterpillars clearly have a broader appetite than has been hitherto discussed!


    • kelway

      By kelway on 02/09/2015

      I am also in south woodford london and have noticed in the last week that my beautiful topiary bushes are all but fast disappearing from right infront of me and no amount of trips to b&q to buy stuff to spray on them seems to be helping


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    • sally-ann gilbert

      By sally-ann gilbert on 02/09/2015

      We are under attack in Buckhurst Hill, Essex, hedges and topiary have been decimated, have found spraying doesnt work, was suggested using a high powered hose to wash them off, that didnt work either, there was an article in the Daily Mail, where it was suggested a Pheramone Trap failing that picking off the caterpillars is the only thing that might seem to work having said that the damage has already been done I feel we are all fighting a losing battle!


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    • kelway

      By kelway on 02/09/2015

      I am also in south woodford london and have noticed in the last week that my beautiful topiary bushes are all but fast disappearing from right infront of me and no amount of trips to b&q to buy stuff to spray on them seems to be helping


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    • kelway

      By kelway on 02/09/2015

      I am also in south woodford london and have noticed in the last week that my beautiful topiary bushes are all but fast disappearing from right infront of me and no amount of trips to b&q to buy stuff to spray on them seems to be helping


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    • kelway

      By kelway on 02/09/2015

      I am also in south woodford london and have noticed in the last week that my beautiful topiary bushes are all but fast disappearing from right infront of me and no amount of trips to b&q to buy stuff to spray on them seems to be helping


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    • sunilavenue

      By sunilavenue on 05/09/2015

      My box balls seem to decimated from the inside of the balls with greenish eggs inside. Can someone diagnose the problem please?


    • anonymous

      By anonymous on 13/09/2015

      We live in the Tarn, SW France where the box tree caterpillar or pyrale de buis has been established for about 2 years. We have treated with Xentari, the bacillus thuringiensis every two months during the hatching season - this targets the caterpillars and DOES NOT KILL other insects. It is effective. We have also hung pheremone traps to catch the adult male moths. DON'T GIVE UP.


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    • sunilavenue

      By sunilavenue on 18/09/2015

      I live in Wanstead in East London. I have spotted box catapillers on several of my box plants which I have disposed!


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    • kaaring

      By kaaring on 19/09/2015

      Half a dozen spotted and hopefully successfully dealt with in the last couple of weeks in NN15. Garden adjacent to wheat field


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    • jules58

      By jules58 on 23/09/2015

      Can anyone tell whether box tree caterpillars are also attracted to other plants, such as Nasturtium and Wasabi? I have founds dozens in the last two weeks eating the above plants in Rutland area


    • Sabine D

      By Sabine D on 05/10/2015

      I live near Cologne. The Rhineland is strongly affected by the box caterpillar. I'm fighting in the third year. The become active here from March / April on. In May the 1st generation pupates, the flight and the first oviposition follows mid-June. By an interval of 5-6 weeks two more generations follow, depending on weather conditions. The larvae of the 3rd generation overwinter in cocoons between the leaves and in the bark. You can combat the larvae of different sprays. The problem is to find the right time to actually hit the larvae, which are protected in the box in a web. I have tried thiacloprid (Calypso), neem and Bacillus thuringiensis (XenTari). With Bacillus thuringiensis I have achieved the best results. But that may be due to the growth of experience. I think the timing of spraying is decisive. The mentioned sprays are effective against the young caterpillars. Therefore I now spray 2-3 weeks after the start of the flight of each generation. At that time the small caterpillars are on the go. And I thoroughly moisten the plants from inside and outside. In my garden are numerous topiary box , some of them very large and quite old. I hope that the birds finally develop appetite for the larvae. Until then I'm looking for the moths. Can anyone share experience with the use of nematodes?


    • Michael Hobbs

      By Michael Hobbs on 17/09/2017

      We've had this infestation this summer and picked off caterpillars, sprayed and fertilized. In the last few days wood pigeons have been all over the box bushes (4 of them this morning) we wonder if they have developed a taste for the caterpillars? The bushes are recovering well.


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