SWARMS of “alien” ladybirds - being reported all across East Anglia - are threatening the survival of native species, experts warn today.

SWARMS of “alien” ladybirds are threatening the survival of native species in Suffolk, experts warn today.

The large harlequin ladybird, which originates in Asia, first appeared in Britain in 2004 after spreading from France and Belgium.

But they are now being seen in their thousands across the region - raising fears for the future of the 46 species of smaller, native ladybird which face being out-competed for food.

The insects are now looking for hibernation sites in homes and other buildings.

The Suffolk Biological Records Centre in Ipswich has been deluged during the past few days with reports of harlequins being seen in homes, buildings and gardens.

Martin Sanford, who runs the centre, said: “Suffolk was one of the first areas to be colonised and they can now be found all over the county.

“But this is the first year that people have reported them in such large numbers. We usually get a peak of records at this time of year when they are finding places to hibernate and gather in warm spots during the day.

“Although the nature conservation concerns are mainly about how much this species competes with other native ladybirds, it is the mass hibernation in houses that has been the cause of public concern in America, where they were introduced about 20 years for aphid control.

“They produce a foul-smelling liquid which stains soft furnishings and have been known to block air vents.”

Mr Sanford said the harlequins had been described as “killer” ladybirds not because they directly attacked native species but because of their threat of out-competing native species for food, leading to their demise.

He said: “Now that they have built up in numbers this may be a real threat, but we don't yet have enough data on the strength of native populations to say how drastic the effect of harlequins will be.”

n Harlequins are highly variable in colour and pattern

n Dubbed by scientists as “the most invasive ladybird on Earth”, the harlequin has strong dispersal capabilities and is most commonly found on deciduous trees, such as lime, sycamore and maple, and on low growing plants such as nettles. They will also inhabit reedbeds, coniferous woodland and crops

N Harlequin ladybirds feed most commonly on aphids, but have a wide food range, also feeding on tiny insects, the eggs and larvae of butterflies and moths, pollen, nectar, and sugary fluids, including honeydew and the juice from ripe fruits.

n When they emerge in the spring, females lay up to 1,000 eggs