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Tiny Caterpillar Returns: Protect Your Hedges with These Approaches

Rapid destruction of box plants may be caused by box tree caterpillars, also known as box caterpillars. Identify these pests by signs like varying-colored larvae and c cater-shaped holes in the leaves. Learn effective methods for managing their infestation.

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Caterpillar returns, posing threat to your hedges: learn effective strategies to manage it
Caterpillar returns, posing threat to your hedges: learn effective strategies to manage it

Tiny Caterpillar Returns: Protect Your Hedges with These Approaches

The Bloody Box Tree Creep: How to Protect Your Box Plants from the Menacing Box Moth

Get warned about the box tree caterpillar, a notorious menace that's been wreaking havoc on box plants in Europe, ruining box balls and hedges in a matter of days! Originally from Asia, these pests have become a significant issue, with the first moths spotted in Britain in 2011, initially in the southeast. They're now prevalent across the UK, with many gardeners blissfully unaware of the damage they can cause. The signs can be similar to box blight, but the box caterpillar is a whole different beast. Let's dive into this bloodsucking pest and learn how to outsmart it!

The Bloody Terror No One Saw Coming

The box tree caterpillar is none other than the larvae of the box tree moth, Cydalima perspectalis. The moth lays its eggs on the undersides of box leaves, and the caterpillars gobble up the leaves, webbing over their messy feeding area as they go. Once they've matured, they form a chrysalis that turns into a box tree moth, which proceeds to lay more eggs. It's a vicious cycle, and a female moth can fly up to 10km, making it hard to control their spread.

The good news? Box tree caterpillars' feeding season is limited to March to October. They survive cold winters, but only start attacking your plants when temperatures are 15°C or above.

Signs of the Bloody Invasion

You're more likely to notice the signs of the caterpillars initially rather than the moths or caterpillars themselves. The signs of the box tree caterpillar include:

  1. Leaves stuck together with webby mess (their ranch dressing to our salad)
  2. Dieback - the leaves have turned papery and pale (a sign they're hungry)
  3. Black frass or droppings among the leaves (the evidence they leave behind)
  4. Lime green and black caterpillars, around 4cm long (big and easy to spot; kind of like St. Patrick's Day, but with a horror twist)
  5. Small yellow eggs on the undersides of leaves (these are like their business cards)
  6. Moths on or around the plant (the adults are around 4cm across, with brown or brown and white wings)

How to Eradicate the Bloody Pests

It's impossible to eradicate box tree caterpillars forever, but there are ways to manage them. Be vigilant, and take action early if you spot signs of an infestation. Here's how:

  • Hand-to-hand combat: Remove caterpillars by hand or prune out the shoot tips that are covered in the webbing surrounding the caterpillar. Keep in mind that this method is time-consuming and isn't feasible for large numbers of plants.
  • Go biological: Biological controls containing Bacillus thuringiensis have been successful for some gardeners. The micro-organism causes the caterpillars to stop feeding within two hours, and they die within one to two days. As it's a biological control, it's safe for garden wildlife. Remember that treatment needs to be repeated several times across the season.
  • Bring out the big guns: Some gardeners have also had success using natural solutions like Plant GP's treatment, while others prefer a 3L knapsack sprayer for more coverage.
  • Use attract-and-trap strategies: A box tree moth trap attracts male moths using a female box tree moth pheromone to prevent them from breeding. A trap won't catch all the moths in your garden, but it's better than nothing. Keep in mind that these traps are not yet licensed in the UK for amateur use.
  • Call in the pros: A new product called Box T Pro Press is available to professional gardeners who have PA1 and PA6 spraying licenses in the UK. It uses a pheromone that makes the area around it smell like a honeypot for female box caterpillar moths, preventing them from laying fertilized eggs. Each dose lasts for three months, which might be useful if you have a lot of box in your garden.

Avoiding Future Infestations

Stay vigilant and act quickly if you spot signs of an infestation. If nearby gardens are showing signs of box moth caterpillar, chances are your garden is affected too. A box moth trap can help you identify whether box moth is present in your garden. If you find yourself fed up with these caterpillars, you might decide to plant a different evergreen that isn't as popular on their menu. Read about our recommended alternatives to box if you decide to part ways with your infested box plants.

  • Monitor your home-and-garden, particularly your private gardens, for signs of the box tree caterpillar to protect your box plants and maintain the landscape of your gardens.
  • Keep an eye open for lime green and black caterpillars, around 4cm long, and small yellow eggs on the undersides of leaves, as these are signs of the box tree caterpillar.
  • Implement a proactive approach to gardening by using biological controls containing Bacillus thuringiensis or natural treatments like Plant GP's treatment to manage the box tree caterpillars in your garden.
  • Maintain a diverse home-and-garden lifestyle by considering alternative evergreen plants if your current ones are frequently affected by the box tree caterpillar to ensure the health of your entire garden environment.

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