A study claims the fast-breeding invader is putting British insects, parasites and fungi at risk.

Since it arrived in the South of England in 2005, the harlequin has colonised Britain at a rapid rate and is now found everywhere from Essex to Orkney. 

This year, an estimated one billion harlequins will devour the eggs of other ladybirds, butterflies and lacewings.

Brought to the U.S. from Asia 25 years ago, the insect was introduced to Britain from continental Europe as an 'environmentally friendly' pest controller.

Experts say its rise is the fastest insect invasion in living memory.

Dr Helen Roy, of the Centre for Ecology and Hydrology, said native insects were likely to suffer 'severe declines' as numbers of the predatory harlequin grow.

'We believe that the negative impacts of the harlequin on Britain will be far-reaching and disruptive, with the potential to affect over 1,000 of our native species,' she said.

'Threat': The harlequin ladybird