WES SHAW Design & Horticulture


Design & Horticulture


Garden Pests – The Box Tree Caterpillar
Simon Ecob

By Wes Shaw

We all love caterpillars don’t we!? Cute furry little critters that often transform into gorgeous butterflies or moths, BUT there is a dark side to these larval Lepidoptera, they have become troublesome garden pests.

They are mainly herbivores so they feed on our precious plants, but I don’t hold that against them… we all have to eat, it’s just that some species have such a voracious appetite that they leave utter devastation and defoliation.

The chief culprit is the infamous box tree caterpillar Cydalima perspectalis that predates on Buxus sempervirens (box).

As a gardener in west London, you can’t turn a corner without seeing box balls or neatly clipped topiary and unfortunately it is being decimated by this pest. This is a real shame because box is a great plant for urban gardens and is used extensively by garden designers and landscapers.

I recently spotted an infected hedge near to me in Chiswick House & Gardens and was shocked at how badly affected it was.

The RHS are researching the spread of the caterpillar/moth and are asking people to report sightings via their website found here. I would encourage gardeners to report any sightings in their gardens.

The box tree caterpillar is relatively new to the UK, it was first spotted in the south of England in 2011. It is native to East Asia, but has been gradually conquering much of Europe and is now set its sight on us! Like most pests that have come from warmer climates it doesn’t have any natural predators in this country so it goes unchecked.

So for gardeners, the question is….what do you do if you find it? Hopefully you will spot it nice and early before it has done too much damage. There are a few options;

  • Remove caterpillars by hand (I will leave it up to you what you then do with them).
  • Spray them with something nasty, I don’t recommend this, not just because of the issues of pesticide use, but unless you are REALLY thorough and are constantly monitoring and spraying it won’t really work, and life’s too short to be out in your garden nuking caterpillars.
  • Use nematodes, a biological control, but results have been mixed, so again not recommended.
  • Replace plants with something else.

I recommend that if you have a couple of plants maybe a nice piece of topiary simply keep an eye out and remove them as and when you see them. If you have a large amount or a hedge, I think the only realistic option is too rip it out and replace with something like Ilex crenata or Taxus bacata a harsh option, but I believe will save you time and money in the long term.

Whatever you decide if you need help, please give me a call. I’m a professional Gardener working all over west London, including Chiswick, Barnes, Richmond, Twickenham, Putney, Teddington and  occasionally venturing into central London.

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