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

A 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.

Caption: Look out for the greenish-yellow caterpillars

Q What can I do to treat box tree caterpillar?

A The caterpillars can be sprayed with a suitable insecticide, such as Py Spray Garden Insect Killer – or you could try the biological control Nemasys Caterpillar Killer – at the first sign of attack. You might also want to trim off the affected parts of the plant and destroy them or pick off the caterpillars and kill them. Agralan sell a pheromone trap to catch the moths.