Harlequin ladybirds: Asian beetles swarming into UK homes as they threaten native species

Like something out of an extremely low-budget horror film, they are coming, in swarms – swarms of ladybirds.

Harlequin ladybirds are entering UK homes by the hundred, by the thousand in some cases – by the tens of thousands if you really want to push it – and there is a danger they might stain your furniture.

With their numbers seemingly boosted by the summer heatwave, they have been seen taking over windowsills, swarming over the headquarters of a wildlife trust, even infesting the bedroom of one of the very scientists who is working to control their spread.

And these are ladybirds of the alien (species) kind.

Originally from Asia, they have reached our shores from North America via mainland Europe. Now they are coming over here, stealing our native ladybirds’ niche in the environment, eating their food and forcing some species like the two-spot ladybird into scarcity.

And they have a sexually-transmitted disease, some of them – a species of laboulbeniales fungus that they spread when mating.

The harlequin ladybird, Harmonia axyridis, is also known as the Halloween ladybird, and right now it is certainly causing alarm, (albeit mostly of the hammed up, mildly ironic variety).

“Attack of the ladybirds update,” said PR manager Helen Ablett as a swarm of harlequin ladybirds scuttled about her windowsill. “It’s officially out of hand, I’ve lost control of the room.”

“Attack of the ladybirds at Pembroke Lodge in Richmond Park,” reported Clare George-Hilley from southwest London. “Incredible scenes of hundreds of thousands of ladybirds flying in the air, on people, on walls, pillars.”

From the official twitter account of the Royal Parks of London came the plea: “We’re being invaded: help!”

At least the people from the Sussex Wildlife Trust were able to shed some light on what was happening – despite the ladybirds crawling all over the wall of their HQ.

“Ladybirds,” they said, “tend to gather together at this time of year, looking for cracks and crevices to hibernate [in] over winter.”

And with more than 50 of the insects sheltering in her bedroom, Professor Helen Roy, co-organiser of the UK and Harlequin Ladybird Surveys, was well placed to explain that the species most likely to be seen entering homes to hibernate was the harlequin.

Other UK ladybird species prefer to hibernate outdoors, in trees or hiding among fallen leaves.

These native ladybird species are coming under increasing threat from the harlequin.

Urging people to report sightings, the Harlequin Ladybird Survey warns: “The harlequin ladybird is the most invasive ladybird on Earth.”

Its march across the globe began in the 1980s when harlequin ladybirds were taken from their native Asia to North America in an attempt at biological control of aphid pests that were eating crops.

The harlequin swiftly became the most common ladybird species on the North American continent.

But it was still introduced into parts of Europe in another attempt at aphid control.

In 2004 harlequin ladybirds somehow reached Britain, either being transported by accident or being blown across the sea by strong winds.

The harlequin poses a threat to many of the 46 native British ladybird species because it can easily out-compete them for food. Its appetite is also so voracious that some harlequins supplement their aphid diets by eating the eggs of other ladybirds.

When it comes to explaining the rapid decline of the two-spot ladybird in the UK, the harlequin is the prime suspect.

And just to make them sound even more sinister, harlequin ladybirds can come in more than 100 different colour patterns, helping them to escape identification by human observers.

The most common forms seen in the UK are orange with 15-21 black spots, or black with two or four orange or red spots.

Despite the threat they pose to other ladybirds, harlequins are mostly harmless to humans. People cannot catch the laboulbeniales fungus even if they touch an infected ladybird, because it only affects insects, centipedes, millipedes, spiders and crustaceans.

If disturbed during hibernation, however, and if unable to find any other food, hungry harlequin ladybirds may bite people, causing a slight sting and leaving a small bump. In a small number of cases, people have suffered severe allergic reactions to a harlequin ladybird bite.

More commonly, however, the danger is to fixtures and furnishings.

The Harlequin Ladybird Survey warns: “As a defence mechanism many ladybird species exude a yellow fluid (called reflex blood) which has an unpleasant acrid smell, and which can stain soft furnishings.”