Box Moth Caterpillar Cydalima perspectalis

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Joanna Savage

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Box Moth Caterpillar Cydalima perspectalis
« on: July 19, 2015, 05:05:04 AM »
This year, since the beginning of July all my box plants in the garden here in Toscana have been severely defoliated by the caterpillar of this moth. There are about twenty plants ranging in age from two to ten years. And now I have heard of hedges in a nearby town, variously said to be two or three hundred years old,with all their leaves eaten, just web remaining on the stems. It has been quite alarming to find ten year old shrubs skeletonised overnight.
My internet research suggests that the moth was introduced into northern Europe from China in nursery material around 2006. Since then it has spread south.
And box has been a mainstay of formal Italian garden design for so long.

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Alisdair

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Re: Box Moth Caterpillar Cydalima perspectalis
« Reply #1 on: July 19, 2015, 08:49:41 AM »
So sorry to hear about that, Joanna. This does seem a dire pest. And spreads so quickly. In 2010 the UK agriculture ministry reckoned it was still more or less contained there, but it's now got a serious grip in south London and seems to be spreading firmly into surrounding region.
Alisdair Aird
Gardens in SE England (Sussex); also coastal Southern Greece, and (in a very small way) South West France; MGS member (and former president); vice chairman RHS Lily Group, past chairman Cyclamen Society

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Pescalune

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Re: Box Moth Caterpillar Cydalima perspectalis
« Reply #2 on: September 05, 2015, 02:02:51 PM »
Dear MGS members,
A good friend of mine, who gardens in London, has sent me the following call for help:

"The  Box tree caterpillar, Scientific name Cydalima perspectalis, Plants affected Box (Buxus), Main symptoms Foliage is eaten and covered in webbing, Most active April-October.  These have made a sudden and most unwanted appearance in Southern England, and I was aghast to get an email from my next-door neighbour to say that several of her young box bushes had been stripped"

I have learned that Provence has also been affected by the caterpillar.

My friend added: "I wondered if you and friends in the Mediterranean Garden Society has been struck by this plague, and if you can offer advice?"
Can you please suggest any sort of treatment that would be respectful of natural resources .
All best,
Jean

Pescalune

Joanna Savage

  • Sr. Member
Re: Box Moth Caterpillar Cydalima perspectalis
« Reply #3 on: September 05, 2015, 03:38:13 PM »
Yes, this is a terrible blow. Since I wrote  the previous note above, I have seen box hedges eaten all over this part of Toscana. My friend, David, manages a historic garden in the Lucca area and he says they are spraying to save the old historical  hedges. He says the leaves will regrow but spraying will always be necessary.
Here, after a month of defoliation I have observed that the plants are still firmly in the ground, so they would probably slowly regrow leaf. Only to be defoliated again next year?
I prefer not to spray for the sake of the wildlife and also the tedious routine involved  so I have decided to replace all my box plants with toughies such as lentiscus and Myrtus, even Lonicera nitida.

nikthegreek

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Re: Box Moth Caterpillar Cydalima perspectalis
« Reply #4 on: September 10, 2015, 10:09:12 AM »
The most readily available, selective and benign treatment I can think of is spraying with Btk (Bacillus thuringiensis subsp. kurstaki). As this affects only the larvae, early spraying (and repeating for a couple of generations) is important. Only host plants should be targeted with spraying. There exist also nematodes that supposedly attack the larvae but I wouldn't know about their availability in the UK. However, one is better to consult local resources with regards to the best recommended, available and legal treatment. I know for a fact that the Box moth has already invaded Northern Italy. 

Btw this is my first post here, pleased to make your acquaintance.

Nik