Support for Caterpillars Encouraged as UK Moth Numbers Decline
As spring arrives and plants begin to flourish, gardeners often struggle against caterpillars feeding on their cabbages. Traditionally, gardeners have been advised on methods to eliminate caterpillars to prevent damage to plants. However, the Royal Horticultural Society (RHS) and The Wildlife Trusts are now encouraging a more tolerant approach towards caterpillars to aid the survival of the moths they develop into.
For plants considered particularly valuable, the RHS recommends avoiding pesticides and instead suggests manual removal, the use of physical barriers, and pruning as alternative methods.
Charities have issued warnings about the significant decline in moth populations, noting that many of the 2,500 species found in the UK are under threat. Since the 1960s, moth numbers have decreased by 33%, attributed to factors such as habitat loss, climate change, and pollution.
Helen Bostock, a senior wildlife expert at the RHS, stated: “Moths have long played second fiddle to butterflies in the garden but understanding their value and needs, and that of their very hungry caterpillars, can support their recovery and help in creating a garden rich in biodiversity.”
Moths are important not only for their intrinsic ecological value but also as a crucial food source for other vulnerable garden wildlife, including birds, mammals, and larger insects.
Caterpillar species vary in their feeding habits; some consume a wide range of plants indiscriminately, while others are specialists. The RHS encourages gardeners to recognize and appreciate the caterpillars present in their gardens. While some caterpillars are large and green and easily visible, others are camouflaged to resemble twigs, bark, or even bird droppings.
These caterpillars eventually metamorphose into visually striking moths such as the pink and green elephant hawk moth, the lunar hornet moth which mimics a wasp, and the contrasting red, cream, and black Jersey tiger moth, which has been observed in the UK as the climate warms.
Caterpillars require substantial energy to transform into moths. The RHS has therefore requested gardeners to “allow for nibbling on ornamentals and vegetable crops.”
The charity also recommends planting native trees and shrubs that support a wide variety of caterpillars, including willow, honeysuckle, foxgloves, verbascum, comfrey, marjoram, bedstraw, sweet william, sweet rocket, tobacco plant, jasmine, and white campion.
Vicki Hird, an insect expert at The Wildlife Trusts, commented: “Moths are stunning in name and beautiful by nature. The green, black and white merveille du jour looks as if it’s been exquisitely painted by an artist, and the white ermine appears to be casually draped in a black-spotted cloak with a warm fur ruff.
“It’s no wonder the French call moths ‘butterflies of the night’. Even little brown moths can have wonderful, intricate markings. Making a simple moth trap is a wonderful way of enjoying these incredible creatures up close before releasing it back into the wild.”
Caterpillar-Friendly Planting
Foxgloves: These attractive plants serve as food for several moth species, including the lesser yellow underwing (Noctua comes), angle shades moth (Phlogophora meticulosa), and setaceous Hebrew character (Xestia c-nigrum).
Lady’s bedstraw: This native wildflower with frothy yellow blooms provides nourishment for the hummingbird hawk-moth (Macroglossum stellatarum), elephant hawk-moth (Deilephila elpenor), and bedstraw hawk-moth (Hyles gallii).
Mullein: These tall, drought-resistant yellow plants are favored by the brightly striped caterpillars of the mullein moth (Cucullia verbasci).
Mint: Mint supports the mint moth and the beautiful plume moth and is also popular with bees.
Hedges: For those with sufficient space, planting a mixed native hedge composed of hawthorn (Crataegus monogyna), blackthorn (Prunus spinosa), hazel (Coryllus avellana), and dog rose (Rosa canina) provides food for a wide range of caterpillars.
