Horticultural society warning over hungry caterpillars

The Royal Horticultural Society (RHS) has issued a warning over hungry box caterpillars stripping leaves from hedges in the South East.

Box tree caterpillars are the larvae of a moth that feeds on box plants. The species is native to East Asia but has been present in Surrey since at least 2014, according to the RHS.

Dr Stephanie Bird, RHS plant health scientist, said: "It would almost be surprising to find a box hedge in the south east that didn’t have the caterpillars in at the moment."

Sarah May, a private gardener who trained at RHS Wisley, said the caterpillar "totally decimates" plants.

The box caterpillar has yellow and black stripes along its body with a black head.

The RHS said the insect's presence can be noticed by defoliation or webbing on box plants.

Dr Bird told BBC Radio Surrey: "If you were to tell me you had a box hedge and suddenly it had no leaves, I would suspect that it had been eaten by caterpillars."

The plant health scientist added while box is a "pretty resilient" plant and can recover from defoliation, the caterpillars can "weaken" the plant.

She said that "desperate, hungry caterpillars" could strip the bark, effectively "killing sections".

Ms May said she "wouldn't now plant box any more", due to the pest.

The RHS advised gardeners to check box plants frequently from early spring so action can be taken early.

The society advocated for non-pesticide methods of removal, which include removing caterpillars by hand or setting pheromone traps.

A Guildford Borough Council spokesperson said: "Box caterpillars have been affecting some areas across our borough. We’re currently not taking any action, but this may change in the future."

The spokesperson said the council aims to avoid using pesticide to protect green spaces.

Follow BBC Surrey on Facebook, and on X. Send your story ideas to [email protected] or WhatsApp us on 08081 002250.