REPORTS of a 'ladybird invasion' have reached York, with readers contacting The Press asking why they were seeing so many of the insects around the city.

Almost 50 species of ladybird are resident to Britain, but since 2004 the Harlequin Ladybird - Harmonia axyridis - has become increasingly prominent.

Although a native of eastern Asia, populations have been found across Europe, Egypt and North America, with some believed to have flown to the UK across the Channel, or having arrived in the country in packing cases.

Dr Geoff Oxford from the University of York's Department of Biology said the higher than normal number of ladybirds around the city in recent days was likely part of the insect's life-cycle.

Dr Oxford said: "Ladybirds are very visible just now and are mostly - on my house at least - are the invading Harlequin Ladybird.

"At this time of year they are gathering in preparation for hibernation, which they often do in groups. They tend to use the same sites each year, presumably marked by scent since a different generation of ladybirds is hibernating now than hibernated last year. So near to where they gather there must be safe nooks and crannies to squeeze into, protected to some extent from frosts."

The Harlequin Ladybird Survey said the visiting insect "has the potential to jeopardise", some local many of these. will monitor its spread across Britain and assess its impact on native ladybirds.

Dr Oxford said the species was introduced into North America as a pest control agent as they eat aphids and other pests, and "have spread extremely rapidly over the last 14 years".

A national study is taking place into the spread of the Harlequin Ladybird - which can live on most trees and low-growing plants, reedbeds, coniferous woodland and crops - and the public has been urged to log sightings of the creature online.

To find out more, or take part in the survey, go to harlequin-survey.org