Gardeners should watch out for a new pest that’s set up home in the UK.

Blue mint beetle [credit: RHS

The blue mint beetle (Chrysolina coerulans) was first reported to the Royal Horticultural Society’s entomology department in July 2011.

One year on, as there has only been a single confirmed sighting, the charity is keen to find out if it was an isolated outbreak – or if the pest is more widespread.

RHS plant health principal scientist Andrew Halstead said the bug was established on mainland Europe.

“The detection of breeding adults in the UK could mean problems for gardeners who grow this herb,” he said.

“It is important that we find out if there are other breeding adults in the UK.”

Adults (7mm long) are black and soft-bodied, making them different in colour to the green mint beetle (emerald green).

Blue mint beetle adults and larvae both eat foliage. The RHS is asking gardeners to check mint plants for tell-tale holes.

Live samples can be posted in stout containers to Advisory Service, RHS Garden Wisley, Woking, Surrey GU23 6QB.