Rosie said you can pick off the caterpillars individually but you have to spot them first.
Box caterpillars usually appear in May, but according to Rosie, it can depend on the weather.
Instead of controlling the problem, Rosie is planning to replace the box hedging in Ham House’s kitchen garden.
In other areas, once the caterpillars are spotted, they are targeted using a biological spray.
Chris Poole, the chairman of the European Boxwood and Topiary Society and his team have been testing out unique, new ways to tackle the problem.
They were contacted by a German company who have a deterrent which could stop the female moths laying their eggs.
In gas permeable pouches, Chris and his team put caterpillar excrement into the hedge.
Another, more simple solution is using the herb thyme.