Ignore those that say the only way to resolve the Box Moth/Caterpillar problem is to dig up your plants. Just look at what happens if you spray and feed your plants – much cheaper and easier than digging up and replacing. Adding pheromone traps to the equation also significantly helps and the more people that do it the fewer fertilised eggs there will be to hatch into caterpillars.
The pheromone traps are working well with the third wave of moths having hatched and now 10 time greater in numbers than they were on the second wave. Hopefully we won’t get a fourth batch, but we will need to keep the traps out and our eyes peeled just in case. It all depends on the sunlight & temperature as the life cycle needs a certain level of ‘degree-days’ to stop it going into it’s overwintering pupae.