Slugs and snails have been knocked off the no.1 worst pest spot for the first time in nearly a decad

Slugs and snails have been knocked off the no.1 worst pest spot for the first time in nearly a decade by a voracious caterpillar which arrived in the UK only five years ago but has made its mark on box hedges all over the south-east of the country.

The box tree caterpillar is the larva of an Asian moth. It feeds mainly on box plants, stripping them of their leaves and covering the bare stalks with a tell-tale webbing.

It accounted for 433 queries - 17% of all those received - to the RHS advice team in 2015, even more than for slugs and snails who only worried less than a third as many gardeners, at 122 queries.

Third in the list were aphids, followed by large cabbage white butterflies, vine weevil and cushion scale.

The RHS advises gardeners with an outbreak of box tree caterpillars to physically remove them from their hedges, or use a biological control (a tiny mite, sprayed on to the leaves, which attacks the caterpillars), or an insecticide.

The plant disease most reported to the RHS was honey fungus, for the 20th consecutive year, while box plants are under further threat from the fungal disease box blight in second place. Leaf spots were third.