Lily beetle, rosemary beetle, berberis sawfly and hemerocallis gall midge are said to be major threats to garden plants, with the potential to cause problems in the commercial sector should they go uncontrolled.
RHS principal entomologist Andrew Halstead said the society was trying to establish the extent of their spread through the use of maps with coloured dots depicting sightings of the pests.
He added: "We are trying to build a clearer picture of where these pests are spreading to. These four particular pests that we have highlighted were selected on the basis that they are non-native pests that have come into Britain and they can cause quite severe defoliation."
"They are equally a problem for the commercial grower because if you have a pest in gardens that is causing real problems it could hit the people growing the plants."
Food & Environment Research Agency principal entomologist Ray Cannon praised the initiative: "What the RHS is doing is excellent. The problem is knowing where everything is and it's very valuable to get this sort of information to see how things are spreading."
The RHS is looking for new ways of controlling the insects to slow their spread and to help gardeners reduce the harm they can cause to their plants. It has advised its members and the general public to report any sightings of the pests through the society's website.
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