Predator ladybirds under attack from native wasps

The harlequin ladybirds from Asia, which were introduced in continental Europe to control pest insects on crops and have since spread to the UK on fruit and flowers and by being blown across the Channel, have become a common sight in the past decade.

Scientists have warned their arrival in the UK is likely to threaten more than 1,000 native species.

The bug is a "voracious" predator, which preys on a wide variety of insects, including the larvae of other ladybirds, caterpillars and even fruit, and out-competes native species.

But now it appears nature is fighting back, with tiny native wasps and flies which commonly lay their eggs in native ladybirds – causing death to the host – now attacking the harlequins.

Scientists investigating the spread of the harlequins are trying to find out whether the parasites are attacking the invasive species at the same rate they target native ladybirds.

Researchers from the Centre for Ecology and Hydrology (CEH) and University of Cambridge are asking members of the public to get involved and "witness evolution in action", by helping record examples of parasites attacking the alien species.

People joining the ladybird parasite survey need to track down some ladybird pupae, usually found fixed to the leaves of broad-leaf trees, conifers and low-growing plants, and take home samples in containers with a clear lid – such as cling film over a yoghurt pot.

They then need to check the pupae every day and see whether an adult ladybird emerges within one to two weeks. If it has been attacked by a parasite, that will emerge instead.

People can record their results, including photographs, on the BBC Breathing Places Ladybird Parasite Survey website.

The CEH is hoping schools will be among those who get involved in the project.