AN INSECT invader has exploded in numbers since being introduced to the United Kingdom 14 years ago, ecologists have warned.

The harlequin ladybird, which originated in Asia, began invading the country from North America in 2004. Since then it has become the most widespread ladybird species and a threat to other British wildlife.

Insect ecologist Dr Alex Dittrich described the Harlequin as the most invasive insect in the family Coccinellidae as they can consume prey such as other ladybird eggs, larvae and pupae.

“One of the things that makes harlequin ladybirds special is that they are polymorphic,” he said.

“They are able to vary in colour and pattern, which makes them similar in appearance to other ladybird species. They also have strong dispersal capabilities and can be found in many places.”

According to Cumbria Wildlife Trust, the explosion in numbers is largely due to the hot summer.

“Having the summer we have just had makes a huge difference” said Cumbria Wildlife Trust’s spokesman.

“We’ve received many calls about homes being clustered with ladybirds. What is happening is that they are now winding down for winter and start to hibernate in clusters.

“They can gather in their thousands in a bark of a tree or on a window sill and will stay there until spring.”

Harlequin pre-adult development takes about 14 to 20 days at 25ºC and adults can begin to lay eggs after five days.

A single female can lay more than a thousand eggs.

These ladybirds are not poisonous but as part of their defence mechanism they may leave a yellow stain, reflex blood, which has an unpleasant acrid smell, and which can stain soft furnishings

“Don’t go persecuting harlequin ladybirds as they are incredibly hard to distinguish between other types of ladybirds.” said Dr Dittrich.

“They adapt easily and quickly, and for now they will hibernate in their clusters until winter blows over.”