Kiwi invaders are on the march, and no greenhouse is safe

MANY gardeners are plagued by mealybugs in their greenhouses, feasting on the roots of their prized plants.

But now the insects’ even hardier New Zealand relations have invaded Britain, and they are leaving a trail of destruction in their wake.

Golden root mealybugs have devastated two gardens in Scotland, with the owners understood to be so upset that they do not want their other ornamental flowers. They leave a golden yellow wax covering the roots after sucking out the sap.

Mealybugs move slowly and the females cannot fly, so infestations are most likely to spread via plants.

The New Zealand mealybugs could have entered the UK in imported plants, plant tools or in the earth on people’s shoes, the RHS said.

Guy Barter, its chief horticulturist, said: “The fact that mealybugs have devastated two gardens indicates they are able to spread. We are in unknown territory.”

Mealybugs are between 1mm and 4mm long, and are covered in a powdery coating which looks like flour – or “meal”. On plants they look like small spots of cotton growing on the underside of leaves and stems.

Infestations are usually noticed when the roots of underperforming plants are examined and insects covered in a golden yellow wax are found attached to the roots. Experts recommend inspecting newly-purchased plants carefully before putting them in a greenhouse.

Kenneth Cox, a Perthshire-based gardening expert and primrose specialist, said it was only a matter of time before the insects spread across Britain. He said the infestation showed the UK was too lax in letting in foreign flora.