Box tree moth
Green caterpillars with black stripes and dots, up to 4 cm long, strip the leaves of box and leave webbing and green droppings. The shrub turns brown and bare from the inside.
The box tree moth comes from East Asia and has few natural enemies here; two to three generations of caterpillars follow each other from April to October.
What can you do?
- From March, regularly look deep inside the shrub for webbing and young caterpillars, and pick them off.
- Blast the caterpillars out with a strong jet of water over a sheet spread underneath.
- For a heavy attack, spray with a product based on Bacillus thuringiensis in dry weather above 15 °C while the caterpillars are young.
- Put affected clippings and caterpillars in a sealed bag in the general waste, not on the compost heap.
- If the shrub is bare but the bark is still green, cut it back: box often regrows.
Prevention
From April, hang a pheromone trap to see when the moths are flying, and let tits and sparrows do their work. If attacks keep coming back, switch to an alternative such as Ilex crenata, yew or privet.
When to watch out: April–October