Asian Box Tree Caterpillar 2017

As your area in France been affected by this caterpillar, it as arrived in our part of the lot this year and as caused devastation to the wild box hedge that is common in the woods and hedgerows of this area, totally destroying large areas.
I have not used the word Devastation lightly, in all my years I have never known or seen anything like it.
Also, the cultured box hedge that people have been treating with love and care in their gardens for years is being killed in a matter of weeks after many years of growing.

It is indeed a problem in large areas of France. There is a solution via Foray48b. It’s professional product and must be applied when the weather is dry and the bees are not flying, ie evening. It is not toxic for bees but that’s the rules.

Pheromone traps are useful but only to trap the moths, not the caterpillars.

Please pm me for more info.


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We have no Box hedges on our farm so it is not a worry to us, but to see the damage on our dog walks alarms us, nobody at the municipal level is doing anything about it.

Are the things otherwise known as procession caterpillars which are toxic to animals

No, totally different beast Lee, If you google the subject you will get a clearer picture, this devastating creature only arrived on our shores about 8 years ago.

You can order Insecticide biologique au bacillus thuringiensis on the internet
You need to spray twice a year
Expensive, hard work if you have loads of box hedge, but worth it. I thought ours was past redemption, it was a mass of brown sticks, but it has made a comeback.


What time of year did you spray Cathy is it too late now ?

I sprayed 2 days ago. If you can buy some locally spray asap. Heartbreaking to see a box hedge that has been tended and pruned for years dying.

BTC (bacillus thuringiensis) is strictly professional and there are strict regulations about using it, especially when bees are flying. Dusk is good when there is no risk of rain (frost is fine).

"Spraying twice a year is simply incorrect. BTC It is a fungus which the caterpillars ingest. It is not toxic to any other insect nor stage of its lifecycle. When caterpillars stop feeding then it is not effective (4th seti pine processionary caterpillar for example).

Now is the correct time to use it on hedge munching caterpillars, they are a different [non toxic] species to processionary caterpillars which stopped feeding in January.



I have a box tree about 8m high and perhaps 4 and a bit around, it has several trunks and has been completely devastated by the caterpillars, they are all over it - can it survive or do I have to chop it down? It would require a massive amount of insecticide as it is so huge and I’m reluctant to spray poison all over it as I try to encourage insects and birds and have lots of fruit trees. I have read that I should chop it down and burn it but it is at least 70 years old so I would really rather not.

After doing some research on this moth and it’s caterpillars, the chances are that a box tree the size of yours should survive one attack but will it survive the second attack, if you do not kill the caterpillars then like Rob Writes you must catch the moth when it re-appears in Pheromone traps to cut down the risk of a more serious attack.

Off I go to the garden shop… thanks!

Bonsoir VĂ©ronique
You can purchase the phéromone traps from if you can kill the caterpillars before they eat every it of foliage then the bush will have a better chance of surviving. So Foray48b is still the best method at the moment.

Another couple of months then the pheromone traps.

I’m in the Cher (18) please contact me if you need any further assistance.


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Update on our box hedge after the Asian caterpillar attack.

I followed Rob’s advice to kill the caterpillars but I noticed Bluetits also eating the caterpillars along with the Lizards who were also helping their selfs.
The hedges have now made a complete recovery and are growing new shoots very well.
The Pheromone traps that I set are now catching and killing a lot of moths, so hopefully next year we should not have such a bad attack if any.

Thank you, Robert Moon, for your advice.


Bonjour VĂ©ronique
You are using very emotive words

That is the difference between qualified pest controllers and “amateur use” is ignorance. Good Pest Controllers use Integrated Pest Management (IPM). As I previously stated BTC (bacillus thuringiensis) is a natural bacteria which only kills caterpillars. There is no secondary contamination (bird eating caterpillar etc). Massive amounts of product/“poison” are not used.

I also recommended pheromone traps which are not toxic or even bird boxes.

There are many ways to Control Pests which doesn’t include polluting the environment. All chemicals used are biodegradable with a residual effect of usually no more than 12 weeks.

Rodent control can be effected by non chemical methods, they just need extra work from the home owner. If rodonticides are used, I usually lift them up after 40 days so there is no secondary risk. All part of the IPM.

Phew, rant over, I get emotional! No need to chop the tree down, it should regrow, see what happens this year. And don’t forget your pheromone trap. Please post a photo of the tree and I will comment further.

Rob IPM Moon!

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Last year we had our first wave of pyrale du buis. Devastating since the landscape is box forest and we still have a box turning industry. And sadly not a cold enough winter to kill overwintering larvae so we are fearing the worst for next year.

Anyway round here we are encouraged to shake and stomp, or bash a buis with a stick, the caterpillars fall off easily, and then we stomp on them. So while we can treat isolated garden box, this is what we will do when we go for walks.

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