A few strands of spider's silk may be all that is needed to keep garden pests at bay, research suggests.
Draping the silvery threads on green bean leaves helped protect the plants from ravaging beetles, scientists found.
The spider's silk appeared to deter the pests, even though no spiders were present.
Even when beetles were trapped in enclosures with the plants, they caused about half as much damage as normal.
A similar but less pronounced effect was seen with silk from silkworm cocoons.
The gardener's tip appears in the Royal Society journal Biology Letters.
Researchers focused on two serious green bean pests, the Japanese beetle and Mexican bean beetle.
Adults of both species are hunted and eaten by web spiders.
Studies were conducted both under controlled conditions both in the laboratory and outside.
In the field experiments, each treated leaf received five strands of spider silk evenly spaced along its length.
The scientists, led by Dr Ann Rypstra, from Miami University in the US, wrote: "These results provide robust support for the hypothesis that the presence of silk reduces the foraging activity of pest insects leading to lower levels of herbivory.
"Spider silk consistently had the strongest impact on leaf damage, whereas silkworm silk tended to have more modest effects"
The freshly drawn spider silk sent out chemical signals that deterred the beetles, the researchers believe.
They added: "It is reasonable to conclude that beetles recognised spider silk as coming from a potential predator.
"Silk has many remarkable properties; these results add plant protection to the list and suggest that strategies promoting spiders and silk production could be important to integrated pest management programmes."
