Plant-dwelling invertebrates from caterpillars and butterflies to woodlice and weevils play a key role in a healthy garden, providing food for other wildlife such as birds, and include helpful predators such as ladybirds and spiders which keep down pests.
Gardeners who want to have a wildlife-friendly garden should put in more plants, particularly native species, reduce pruning and turn a blind-eye to the odd nibbled leaf or first sign of a pest attack, the RHS suggested.
The advice from the garden experts comes after their four-year “plants for bugs” research project which was designed to test whether the geographical origin of garden plants affect the amount and different types of insects and spiders they support.
The study, published in the journal Biodiversity And Conservation, looked at 36 garden-border sized plots planted with perennials and shrubby plants native to one of three geographical regions, the UK, the northern hemisphere excluding the UK and the southern hemisphere.
All the regions supported large numbers of invertebrates, but the borders filled with native plants did best, supporting 10% more than the second-best borders with plants from the northern hemisphere.
The southern hemisphere planting supported a fifth fewer invertebrates than the native planting, the study found.
Across all the plant groups, regardless of where they came from, the more densely they are planted, or allowed to grow, the greater the amount of all types of bugs they supported.
The RHS suggested attractive native plants that gardeners can add to borders to boost wildlife include foxgloves, purple loosestrife, common honeysuckle and heather.
RHS principal entomologist Dr Andrew Salisbury said: “The presence of a wide range of invertebrates, such as ladybirds, springtails, spiders and even caterpillars are indicators of a diverse and well-functioning garden eco-system, and so should be encouraged and supported.
“While some of these animals, particularly herbivores, are traditionally regarded as pests by gardeners, they are vital to support healthy populations of natural predators which in turn help keep pest populations under control.
“And they provide food for garden birds and mammals such as hedgehogs. In short, an abundance of bugs of all types equates to healthy garden ecology.“
He said: “In order to help create a positive environment for these valuable invertebrates to thrive gardeners should plant plenty of plants from the UK and relax; refrain from…