Millions of alien ladybirds riddled with sexually-transmitted diseases are coming to Britain.

The mass invasion of Harlequin ladybirds could ruin our furniture and Christmas party season.

The bugs, which have black wings rather than our common red, are from Asia and North America on the mild autumn winds. They pose a threat to our native ladybirds because they carry an STD called Laboulbeniales.

Scientists say the fungus, which is passed on through mating, will infect our native species which are already under threat from habitat loss.

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While they don't yet know if the fungus is harmful, the UK Ladybird Survey says it is possible that the disease affects the lifespan or the number of eggs a female can produce over her lifespan.

Professor Helen Roy, of the Centre for Ecology and Hydrology in Wallingford, Oxon, warned "These ladybirds also feed on grapes so they are often found in vineyards which, of course, becomes a problem for wine production."

A spokesperson for Bugslife nature charity said: "Large gatherings of them can give off a chemical smell and in centrally-heated houses they may be woken up from hibernation by the warmth and fly around the house."