How to get rid of box tree caterpillar

There are a few problems that can hit box, including box tree caterpillar, box sucker and box blight. Read our guide on how to get rid of them and protect your garden.
Chad EnglandContent lead
Trimming box

Box (buxus) has been grown in the UK since Roman times and is loved for topiary or neat hedging. However, a number of problems have cropped up in recent years making the plant’s future in our gardens uncertain.


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How do I know that it's box tree caterpillar?

So far this devastating pest, which can completely defoliate plants, has only affected plants in the England, but it may spread further. Webs on the leaves and greenish-yellow caterpillars are likely to be the first sign of attack. The caterpillars are 1.5-2cm long. You may also find pale-yellow eggs on the undersides of the leaves. The eggs later develop a black spot. The moths have a wingspan of around 4cm and the wings are white with a dark-brown border.

What can I do to treat box tree caterpillar?

The easiest method is to be vigilant and pick off the caterpillars and kill them. Search deep inside the plant as you may find some hiding there.

The caterpillars can be sprayed with a suitable insecticide or you could try the biological control Nemasys Caterpillar Killer at the first sign of attack. You could also try a pheromone trap to catch the moths.

Suppliers of biological control: Nematodes Direct; Green Gardener

Suppliers of pheromone traps: Dragonfli; Thompson & Morgan

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How to get rid of box sucker

What is box sucker?

Box sucker is a tiny insect, also known as a psyllid. It feeds by extracting sap from leaves, leading to distortion.

What damage does box sucker do?

Immature box suckers, or nymphs, feed on young shoot tips. They secrete chemicals into the plant which prevent the shoots developing properly — the leaves become curled and congested, looking like little Brussels sprouts on the shoot tips.

How do I recognise box sucker?

You need to look carefully among the leaves to see the insects themselves. The nymphs are pale green, less than 2mm long, and their bodies are flattened like a bed bug. You may also see patches of sticky honeydew, which often attracts sooty mould. The nymphs also produce quantities of a white, waxy secretion, which can accumulate on or around the plants.

What plants does box sucker attack?

Box sucker only attacks box plants. A different species of psyllid, apple sucker, attacks apple blossom, and other types of sucker can damage bay, elaeagnus and eucalyptus.

How serious is box sucker?

On regularly clipped plants the damaged shoot tips will normally be removed, so the damage is not serious. It can be more of a problem on young plants, or developing topiary, as the distorted shoots retard normal growth.

What is the life cycle of box sucker?

The sap-sucking nymphs are most abundant in April and May. They mature into winged adults from late April to June and eggs are laid on young stems in late summer. These overwinter and hatch the following spring.

How do I control a box-sucker attack?

On young plants, nip out damaged shoots as soon as they are seen. With older plants you can wait until normal clipping time. A second clip in late summer should remove most of the eggs. All clippings should be burned or binned, or put in a large-scale composting system, not your own compost heap.

Are there any suitable sprays for box sucker?

Products recommended for aphids should also help control psyllids if used in spring when the nymphs are feeding.  

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How to get rid of box blight

How do I recognise box blight?

This fungal disease is becoming increasingly common, causing unsightly bare patches and dieback in box. It’s most common in rainy weather. There are two fungi that cause the problem: both make the leaves turn brown, and one also leads to black streaks on young stems and dieback. You may also see white spores on the undersides of the leaves.

How do I treat box blight?

Bronze-coloured leaves can also be caused by a lack of potash, so it’s worth feeding with tomato feed before you take anymore drastic action to check whether it’s this, rather than box blight. 

If it is box blight, it’s often best to dig out and destroy any affected plants. However, if you’re keen to keep some of the plants, try cutting out the affected parts and picking up all the fallen leaves, plus the surface soil, underneath the plants.

There are no chemicals specifically recommended for use on box blight, but you could try a fungicide for ornamental plants.

How do I avoid box blight?

To help avoid the problem, try not to clip plants too often so they grow a bit looser and air can circulate easily. Also avoid growing other plants too close to them, and try not to get water on the plants when watering. It’s a good idea not to trim box when wet weather is forecast. Some varieties seem more blight-resistant than others, such as B. microphylla ‘Faulkner’ and B. microphylla var. japonica ‘National’.

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Alternatives to box (buxus)

If you’ve decided that you don’t want to grow box anymore but are still looking for a shrub with neat, evergreen foliage that responds well to pruning, try these plants instead: 

Yew (Taxus baccata)

Usually grown as a tall hedge, yew can be kept as low as 30cm high if you trim it. It’s a dense evergreen and works well as topiary.

Japanese holly (Ilex crenata)

A slow-growing, dense shrub with small dark-green leaves. It works well as a hedging plant.

Lonicera nitida

A fast-growing hedging or topiary plant. Clip regularly in summer and autumn for dense growth. Dislikes wet or windy sites.

Phillyrea angustifolia

This evergreen makes a good hedge or topiary specimen. Beware in colder areas, though, as it’s sometimes hit by frost.

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