16 April 2026

Help! My box has been attacked by caterpillars.

Q. “Help! My box has been attacked by caterpillars. I had presumed it was box blight but found caterpillars within the dense plant. There are a few green healthy looking areas left. What do you advise we treat with? Can we save the plants.” Many thanks Sarah

A. Thanks for the message and sorry the box caterpillars have found your plants. Its going to be a 3 pronged solution :-

• Use Box Caterpillar Nematodes to kill the caterpillars already present.

Use these Box Tree Caterpillar Nematodes (containing a unique mix of different nematodes called NemaMix) to control Box Moth Caterpillar on your box plants. Box Tree Nematodes are safe to use and will not harm pets, children, wildlife or bees. We supply 3 sachets of F&V Nematodes, which are applied 3 times at 7 day intervals. Supplied in sachets as a powder, it is mixed with water and applied with a sprayer treating up to 50sqm– to treat a smaller area just make the solution stronger as it is impossible to overdose. Box Tree Nematodes are a living, perishable product (it will keep for 2 weeks in the fridge), so order when you are ready to apply and the caterpillars are present. Each pack treats 50 sqm. 

• Use a Box Moth Trap to then catch the male adult moths to give on-going control (if not males are present only unfertilised eggs will be laid and this cuts down on caterpillar activity and allows you to monitor how widespread the moths are in your area.

Use the Box Tree Moth Trap to protect your box plants if you know there are moths in the area or position to monitor moth activity in your area. Each trap is supplied with our unique SEASON LONG pheromone lure – the Ginko Buxus lure we include will attract moths for around 240 days unlike our competitors lures, which only last for approx 6 weeks, so it works out much better value for money in the long run PLUS you do not have to remember to change lures every 6 weeks! The lure is added to the top of the trap and secured with the tie included. The trap is designed to be re-usable, so a replacement lure can be purchased the following season and the trap re-used. Each Box Tree Moth Trap comes complete with 1 seasons worth of lure. Use 1 trap per 200 sqm. 

• N.B. Keep checking you plants for new moths as the traps will not protect from female moths already fertilised before they enter your garden.
• Feed your plants with Topbuxus Grow to help the plant recover from a Box Moth Caterpillar attack.

For healthy green, blight free box trees / hedges/ balls and topiary apply TopBuxus GROW Fertiliser. Box plants have been under attack recently from both box blight and Box Tree Caterpillar , which makes the plants unsightly. TopBuxus Grow Fertiliser has been specifically developed by a buxus grower to encourages healthy, green growth and to help plants recover from attacks. Apply at a rate of 50g per sqm 3 times a year. This fast-absorbing mineral fertiliser on a 100% natural base is quickly absorbed by the plants without the need for lots of watering, which would increase the risk of box blight. Supplied in either a 500g tub – treats up to 10 sqm or in a 5kg tub, which will treat up to 100 sqm. 

I hope this helps

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