The bug was found on mistletoe in Somerset

The tiny insect, known as Hypseloecus visci, was discovered on the festive plant at National Trust gardens at Barrington Court and Tintinhull, Somerset.

Previously known only in France and Germany, the black bug is one of three new insects found during the Trust's Wildlife in Gardens survey.

Measuring less than a quarter of an inch (3mm), the insect sucks sap from the leaves and stems of the plant to survive.

Rare insects

In addition to the mistletoe bug, the survey also found a small, harmless paper wasp - Polistes dominulus - at Ham House in Richmond, London and a small fly called Homonera indistincta at Montacute House in Somerset.

Matthew Oates, the Trust's nature conservation adviser, said: "Most of the gardens surveyed turned up as many rare insects as the average small nature reserve.

"This is clear evidence that a wealth of weird, wonderful and new wildlife lurks undiscovered in our gardens."

There are 1,500 species of mistletoe worldwide and most grow in the tropics - Britain is on the northern edge of the plant's range and is home to just one species.