Home remedies used by gardeners to deter slugs and snails are to be tested scientifically for the first time.
Researchers at the Royal Horticultural Society are investigating whether the likes of egg shells and copper have any effect in keeping slugs away.
The RHS is starting scientific trials of five traditional remedies to see if they are based on science or myth.
Dr Hayley Jones says the results, available in the autumn, will help them advise gardeners with real confidence.
“It will really start to tell us how well some of these barriers work,” she said. “Is it worth spending your time and money on them?”
Until now there has been no formal study of the benefits of copper tape, sharp horticultural grit, pine bark mulch, wool pellets and egg shells, compared with doing nothing, she said.
“With slugs and snails regularly topping the list of gardener complaints we want to know if home remedies have a role to play or are nothing more than a ‘plants man’s placebo’,” said Dr Jones, an RHS entomologist.
The methods will be tested at the RHS research facility at Wisley Gardens, on lettuce plants grown in pots and raised beds.
The plants will be examined weekly for signs of damage and, at the end of the experiment, all the lettuces will be harvested and weighed.
Meanwhile, a garden at this year’s RHS Chatworth Flower Show, will highlight the importance of plant health.
Dr Jones said many people don’t realise that slugs can be an important part of the ecosystem in the garden.
They are “super interesting”, and often overlooked, she added.
Common misconceptions include:
All slugs are pests
There are more than 40 species of slug currently found in the UK, with only a small number of these considered as pest species. Not all slugs feed on vegetation; some eat fungi and a small number are carnivorous, feeding on the likes of earthworms.
Slugs all look the same
For many people, the large, black Arion species of slug springs to mind; yet those that are tiny, up to 2cm long, can be the biggest pest.
The rise of Spanish “killer” slugs
While invasions of cannibal slugs from Spain (Arion vulgaris) have attracted attention, most slugs will eat another dead slug if they find one.
One home remedy that has yet to be tested is beer. Some have advocated putting out a saucer of beer to tempt Spanish slugs to an early end.
No-one has yet done “real scientific studies” on beer and slugs, but it was an area of interest, said Dr Jones.