Invading cannibal ladybirds take over Britain's homes

Asian interlopers devour native insect populations and exude chemical that could ruin your curtains

It started with the squirrels – Britain's native reds being ousted by their ruthless grey American cousins. Now another battle is unfolding, one which could be even more catastrophic for an iconic species. Ladybird wars have broken out in the UK – and this time humans are caught in the crossfire.

An explosion in the number of harlequin ladybirds has led to people's homes being infested with the creatures – and threatened native ladybirds.

While the two-spotted and seven-spotted varieties are emblematic of the British countryside, the larger harlequin, first seen in the UK in 2004 and now numbering billions, has become the nation's most abundant species. Rather than feasting on aphids and greenfly, the harlequin also eats lacewings, hoverflies and even other ladybirds.

Dr Helen Roy, head of the national survey, said: "They are spreading at 100km per year, one of the fastest spreading insects worldwide."

The harlequin is a formidable opponent – in particular for the two-spotted ladybird with which it shares an ecological niche. Since the arrival of the harlequins, the two-spotted population has declined by as much as 30 per cent.

Ladybirds are brightly-coloured because they contain defensive toxic chemicals. The harlequin carries a more potent toxic cocktail and is larger than the two-spot. The invaders eat the larva of their British country cousins.

The two-spot, once the second-most common of Britain's 47 species, would not make the top 10 now, Dr Roy said.

The Harlequin, native to Asia, was introduced to America in 1988 and has become the dominant ladybird species on the American continent. The species has invaded most of western Europe, with the UK population growing from a small corner of south-east England to dominate the entire country, as well as parts of Scotland, Wales and Northern Ireland.

They have been known to hibernate in great numbers in dry places like garages and sheds in the autumn.

The harlequin menace is not contained to the insect world. Although they pose no threat to human health, they can be murder on the wallpaper. Last year's wet summer led to an explosion in their numbers and they are now taking winter refuge in houses.

Dr Trevor James, entomologist at the Biological Records Centre: Centre for Ecology and Hydrology, said: "The harlequin has a preference for buildings, and goes into a dormant phase over the winter time. If disturbed, they exude a yellow substance from their knees, which can stain wallpaper."

Noel Shiel, sales technician for rug and upholstery cleaners Pilgrim Payne, which has two Royal Warrants, for both the Queen and Prince Charles, said staining from ladybirds has increased threefold this year.

"There's a real epidemic, they are in almost every home. They seem to be attracted to sash and wooden window frames, and crawl up curtains, leaving orange stains." He said he had seen ladybird damage in some of London's smartest homes, including those in Eaton Square and Sloane Square. The Syrian Embassy had a big problem with ladybirds earlier this year.

Dr Roy does not recommend killing the harlequin, because insecticides could also harm the two-spot. But Tony Halliday, managing director of pest control company Biopest, said he treats ladybird call-outs with a residual insecticide.

And Dr Roy, who currently has more than 400 harlequins gathered in her window frame, believes the insects are here to stay.

It is bad news for the 0.1 per cent of the population estimated to have a phobia of ladybirds. Emma Citron, consultant clinical psychologist from the British Psychological Society, said: "It's not as common as a phobia of spiders, which affects up to five per cent of the population, or dogs, which affects around two per cent. I have helped people with a fear of ladybirds, and there is very little research to suggest it's caused by a bad experience or trauma.

"If someone is trying to tackle a fear, they should start by looking at pictures of ladybirds, using the words 'lady' and 'bird' in their conversation. Next, approach ladybirds, holding them in one hand, firstly far away from the body, then closer.

"People can try to help themselves get over their fear, but in extreme cases - if for example they would turn down invitations to parties in gardens because they are scared - they need help."

A bug's life: know your ladybirds

Harlequin ladybird

First seen in the UK in 2004, the harlequin is now the most populous species of ladybird. Feasts on aphids, other ladybirds, lacewings, hoverflies. Spreading at more than 100km a year, it is rapidly conquering the country.

Seven-spot ladybird

Goes into leaf litter over the winter months. Historically, the most populous species seen in gardens. Now the second most numerous species, with distribution remaining high.

Two-spot ladybird

Suffered dramatic decline since the arrival of the harlequin. A decade ago, it was the second most populous species, now not in the top ten of the 47 ladybird species in the UK. Feeds on aphids, shelters in people’s homes over winter months.

14-spot ladybird

This aphid-feeder yellow ladybird has square spots. A common species, which has seen a rise in numbers this year.

Kidney spot ladybird

This small, black ladybird with two red spots feeds on tiny insects. Often seen on deciduous trees, and hides in the cracks of deciduous trees over winter.

Orange ladybird

This ladybird feeds off mildew. Experiencing a huge distribution increase, thought to be because the warmer, wetter weather in the UK gives it more food.

Eyed ladybird

Britain’s biggest ladybird, feeds on aphids, most usually found on conifer trees or sheltering in leaf litter over winter.