Shropshire has been hit by a plague of flies, with large numbers making a late appearance across the county.

Residents in Shrewsbury, Ludlow and Shifnal have complained about the problem, with some having to call in exterminators to deal with dozens of them at a time.

The infestation of cluster flies has been put down to the unseasonably warm weather delaying the winter chill.

Questions have also been asked about whether the appearance of the flies could be a sign of global warming.

Valerie Harper, 52, from Shifnal, said: “I was surprised when I opened the window in my bedroom to find half a dozen flies flew in.

“The next time about 20 flies flew in.

“My partner said he thought they must be hibernating in the gaps around the window.”

John Hughes, from Shropshire Wildlife Trust, said residents could expect to see more flies as winter seemed to be getting warmer in the UK.

“It’s because it’s been so warm, until this weekend it’s been incredibly warm.

“All insects work on temperature – if it’s too low they don’t move but if it rises they become active.

“They get into houses and as people have very warm houses they get very active and start flying around.”

He said flies tended to go into cooler places such as lofts to hibernate.

He added: “Is it global warming? Quite a distinct pattern is emerging so we should expect to see things we tend to associate with warmer seasons.”

Shropshire Council has also seen a large increase in reports of flies.

Gareth Proffitt, council spokesman, said: “This autumn our pest control team has seen a big increase in the number of calls and complaints about cluster flies, which often come into homes at this time of year to spend the winter in lofts.

“However, for a small fee our pest control officers are able to visit and treat lofts where cluster flies are present, to remove flies for the duration of the winter.

“For more information about this service, which is provided between December and February, people can call 0345 678 9000.”

Mr Hughes said: “If we get a cold snap they should all disappear again, some will die and some will go into hibernation.

“The flies are an important source of food for the birds.”

By Emma Kasprzak