March of very hungry caterpillars

A PLAGUE of caterpillars is laying waste to hundreds of hedges in gardens across the area.

Box tree moth caterpillars strip box hedges of all their leaves, turning the evergreen shrubs into brown skeletons, which stand out from neighbouring plants whose leaves the insect larvae do not eat. Although the leaves can grow back, experts warn that repeated attacks weaken the evergreen hedges – and many gardeners have been digging them up completely.

Among those whose gardens have been hit is Dave Barrett, who has cut his own hedge back close to the ground after it was attacked.

Dave’s box, or buxus, hedge was planted by a previous owner of his house in Downend, and is believed to be about 30 years old.

He said: “The hedge was a beautiful thing but I had to drastically prune all the greenery off and burn it, as it seems the only way to give it a chance at continuing to live and not infect other hedges. I’m hoping it will come back and what I’ve done will make it manageable. On a quick walk from Frenchay Road to Staple Hill I noticed every hedge of the same kind appears to be dying.” 

Royal Horticultural Society expert Dr Andy Salisbury said reports of the invasive box tree moth had seen a “huge leap” in the Bristol area this year. 

He said: “Since first being reported in English gardens in London in 2011, box tree moth has spread rapidly across the UK.

“However, it wasn’t until 2017 that is was first reported to the RHS from the Bristol area.

“Numbers of reports have gradually built up since then. This year, however, has seen a huge increase in reports – at the end of May we had already received nearly 700 reports, which is more than year totals 2021 and 2022 combined!    There are two generations of caterpillars a year and it can strip box plants; although plants can survive, this successive defoliation will weaken them.”

The RHS recommends trying to remove caterpillars by hand and or applying nematodes – a tiny animal that feeds on the caterpillars and can be ordered in packets online or from garden centres.

Pesticides should only be used “in a minimal and highly targeted manner” and avoided if nearby plants are flowering, as they will kill bees.

Dr Salisbury added: “There is hope – there is evidence that predators such as birds, social and parasitoid wasps are beginning to find and eat the caterpillars; the RHS is carrying out research to find out more.” 

Some gardeners are planting alternative species of hedge instead. More information on control and alternative plants can be found online at