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Box tree caterpillar

Hi, I would be grateful for advice or idea. We planted a small box hedge several years ago. It is still pretty small but was healthy until last year when it was attached by box tree caterpillars. I noticed the problem in late July or early August. To my horror. My husband googled it. It turned out to be that last summer some areas in north-east London and Essex were invaded. My small hedge was among unlucky ones - several other properties in our area have box hedges and they were spared. I am happy for them.
We spent many - I mean many - hours on our knees picking up these pests. And we managed to save the hedge. My husband also bought some spray, to use, but he was told by a local nursery that it is not really effective. Better this than nothing.
This summer I was keeping an eye on the hedge. Checking it regularly and picking caterpillars. Time consuming and frustrating. The other day I checked the hedge again. No new caterpillars (not surprisingly - at the end of October) but there were signs I missed some :(- and they are ready to emerge next summer.
I do not want to get rid of my hedge. It still has many new shoots. But an idea of spending next summer on my knees again is not very appealing.
What if I cut down my hedge pretty low, to get rid of my uninvited and unwelcome lodgers?
Any thoughts?

Comments (5)

  1. Grower

    Rachel the Gardener

    Hi Irene,

    Well done in spotting it and picking the little blighters off: you've probably saved the poor hedge!

    Unfortunately, there isn't anything you can spray with to prevent it next year: but you can spray with a pesticide containing Bacillus thuringiensis as the active ingredient (Bayer Provado uses this chemical) and that will kill the caterpillars when they nibble the leaves. So it won't prevent them, but it will kill them once they start working on it.

    You can also help the hedge by getting it as healthy as possible: shake out all dead leaves, rake up all dead material underneath it, try to get a bit of airflow through the hedge by thinning out a little, if you can: give it a good feed in early spring and keep it well watered. The stronger the plants, the more resistant they will be and the faster they will spring back from any attack.

    Hope this helps!

  2. Grower


    Hi. Hope you have managed to find a solution for the caterpillar infestation to your Box hedges. My horticultural college-mate who is a senior gardeners in one of the famous London garden squares swears by this Vitax's Py Bug Killer Concentrate Garden Spray, 250 ml by Vitax Ltd . Do give it a go and let us know how you get on. Mine seems to be free of these little blighters so far. Touch wood. I heard another horror story from anther of my college-mate. She witnessed hundreds of these caterpillars crossing the road from one front garden to another , destroying both houses' Box hedges in record time ! Good luck .

  3. Grower


    Thank you, will definately give it a go. This absolutely Haloweenish story about caterpillars crossing the road - where did it happen? In London?

  4. Grower


    Usually people are spraying their box trees too late. Caterpillars in early stages might be difficult to detect. And there are few waves during the growing season. We are trying to avoid box borders and balls. Planting substitutes instead. In the video below you can see box trees in South London last summer. 2:25 you can see pheromon traps. They atracts male moths and interrupts breeding cycle. There is no single remedy. Success depends on early detection, timely spray with insecticides, traps for adults, manual picking when possible, reducing patches of box trees and using substitutes. Cydalima perspectalis in London.

  5. Grower


    Hi, beware! They are back! Spotted new, young and most probably very hungry caterpillars on new shoots. Sprayed the hedge. Not sure whether it did any good. My husband and I are very upset. But determined. Will fight them!

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