Bold truth: protecting caterpillars is essential to saving the UK’s moth population, which is crashing. As spring brings new growth, many gardeners find themselves battling caterpillars chewing through their cabbages. Yet a growing chorus of experts says we should rethink how we respond, not just to protect plants but to preserve moths that depend on them.
Rather than reflexively spraying or pulling every caterpillar off, the Royal Horticultural Society (RHS) and the Wildlife Trusts are urging Britons to take a more relaxed stance toward caterpillar damage in order to safeguard the moths these larvae become. For especially cherished plants, they advocate pesticide-free methods such as hand-picking, barriers, and pruning to minimize harm while still supporting moth life cycles.
Moth populations are in decline, the charities warn, with around 2,500 UK species at risk. Since the 1960s, numbers have dropped by about 33%. This downturn stems from habitat loss, climate change, and pollution. Helen Bostock, a senior wildlife expert at the RHS, notes that moths have long been eclipsed by butterflies in garden discourse, but recognizing their ecological value—and the needs of their hungry caterpillars—can help drive recovery and boost garden biodiversity. Moths matter not only in their own right but also as vital food for other wildlife facing threats, including birds, small mammals, and larger insects.
Some caterpillars wander aggressively, devouring many plants, while others are specialists with specific diets. The RHS encourages gardeners to appreciate these caterpillars and the roles they play. Many species are easy to spot—large, green, or boldly colored—while others are camouflaged as twigs, bark, or even bird droppings, making them easy to overlook. When they transform, they become striking moths like the pink and green elephant hawk moth, the lunar hornet moth disguised as a wasp, and the Jersey tiger moth, with red, cream, and black markings. The Jersey tiger moth is showing up more in the UK as climate warms.
Caterpillars require substantial energy to finish metamorphosis into moths. The RHS therefore suggests permitting some nibbling on ornamentals and vegetables, within reason, to support their development. The charities also recommend cultivating native trees and shrubs that provide sustenance for a broad range of caterpillars, including willow, honeysuckle, foxglove, verbascum, comfrey, marjoram, bedstraw, sweet william, sweet rocket, tobacco plant, jasmine, and white campion.
Vicki Hird, an insect expert at The Wildlife Trusts, highlights the beauty of moths—describing species like the green, black, and white merveille du jour as if painted by an artist, and noting the white ermine’s delicate, spotted cloak. She also explains why moths have earned the moniker “butterflies of the night” in French, and reminds us that even humble brown moths can boast intricate patterns. A simple moth trap offers a close-up, low-impact way to enjoy these creatures before releasing them back into the wild.
Caterpillar-friendly planting ideas
Foxgloves: This prize among garden plants feeds several moths, including the lesser yellow underwing (Noctua comes), angle shades moth (Phlogophora meticulosa), and the setaceous Hebrew character (Xestia c-nigrum).
Lady’s bedstraw: A native wildflower with airy yellow blooms that sustains the hummingbird hawk-moth (Macroglossum stellatarum), elephant hawk-moth (Deilephila elpenor), and bedstraw hawk-moth (Hyles gallii).
Mullein: These tall, drought-tolerant yellow blooms support the brightly striped caterpillars of the mullein moth (Cucullia verbasci).
Mint: A magnet for the mint moth and beautiful plume moth, and a favorite among bees.
Hedges: If space allows, a mixed native hedge containing hawthorn, blackthorn, hazel, and dog rose provides habitat and food for a wide array of caterpillars.
