Gardeners have been urged to look out for a particular caterpillar that is ruining plants (Image: Mariia Zotova via Getty Images)
Garden enthusiasts are being alerted to the threat of invasive caterpillars wreaking havoc on their cherished plants. The UK is experiencing a surge in caterpillar populations that are decimating topiary and hedges, prompting calls for vigilance among gardeners, reports the Mirror.
The box tree moth caterpillars, notorious for devouring box leaves and bark, can leave shrubs stripped bare and discoloured, much to the dismay of those who take pride in their ornamental hedges and neatly trimmed box borders. These infestations can be catastrophic, often resulting in the need to remove or replace affected plants. An ecologist from Arbtech warned: “Box tree moth caterpillars might look harmless, but they’re an invasive species that can strip a healthy plant in no time – and because they often feed from the inside out, many people don’t realise there’s a problem until it’s too late.”
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Caterpillars can destroy garden plants if they aren’t dealt with (Image: Getty)
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With box hedging being a staple in British gardens, the burgeoning numbers of these caterpillars are causing significant damage, not just to the aesthetics of gardens but also hitting owners in the pocketbook.
“We’re urging homeowners to check their plants regularly over the summer months. Look for tell-tale signs like webbing, leaf loss, or green-and-black striped caterpillars,” the experts said.
“If you spot an infestation early enough, treatment is possible using biological control or specific pesticides, – but swift action is essential to save the plant and stop the spread.”
Five tips to help prevent box tree caterpillar damage
Check box plants weekly for signs of leaf loss or webbing
Regular inspections are the most effective way to detect an infestation early. Box tree caterpillars typically begin feeding from within the plant, meaning damage may not be immediately apparent.
Watch for nibbled leaves, unexpected browning, or sparse areas. Webbing at the plant’s centre – frequently confused with spider silk – is a telltale indicator.
You might also notice black pellets (droppings) around the base or amongst the foliage.
Gardeners need to keep an eye on their box plants and hedges after a surge in the pests (Image: Getty Images/iStockphoto)
Watch for green caterpillars with black heads and white stripes
Box tree caterpillars are easily identifiable once you understand what to seek. They’re vivid green with black heads and prominent black and white stripes along their bodies.
If you discover one, there are probably others in the vicinity. Early detection is crucial to preventing severe damage to your box plants.
Remove caterpillars by hand where possible, or using approved treatments
For minor infestations, caterpillars can be removed manually – just ensure you’re wearing gloves. If the issue is more serious, utilise a biological insecticide that specifically targets the caterpillars without causing harm to bees or other wildlife.
Timing is key – aim to treat when the caterpillars are actively feeding, typically in late spring and again in late summer.
Dispose of affected clippings carefully to avoid spreading the moth
If you prune or remove an infested plant, dispose of the clippings responsibly to prevent spreading the moth. Home composting is not recommended as eggs or larvae could survive and propagate.
Instead, bag up the waste and take it to a local recycling centre that handles green waste, or adhere to your council’s guidance.
Avoid unnecessary pruning in peak months
Pruning stimulates new, soft growth – exactly what box tree caterpillars love to eat. To avoid attracting them, try not to prune during peak activity months (usually April to September).
If trimming is needed, do it in late autumn or winter when caterpillars are inactive. Over-pruning in summer not only weakens the plant but also makes it more attractive to egg-laying moths.
Keeping your box plants in good shape without excessive cutting will help reduce their vulnerability to infestations – and keep your garden looking healthier for longer.