Rats in Shropshire are becoming immune to poison

There are also claims rats in the UK are becoming bigger, and some are even developing resistance to traditional methods of control. But those trying to deal with infestations on their own could be doing more harm than good, making the pests ill rather than killing them.

David Harbinson, who works at Shropshire Pest Control, said: "It seems in the last two years we have seen an increase in rats and mice in the area and we also get a lot of calls about squirrels, especially in the Telford area.

"I would say that around 50 per cent of our customers come to us first, but the other 50 per cent have gone to hardware stores to buy rat poison. We use stronger stuff that contains the chemical bitrix, which is not harmful to humans. What people buy in hardware stores can just make the rodent ill rather than destroying it."

Normally people would call out pest control officers from their local authorities if their homes were infested with mice, rats, wasps or other pests. Many councils have offered free assessments, and then made subsidised charges for proofing, poisons or other recommended measures.

The decline in local authority services means more people are likely to attempt ineffective and sometimes dangerous DIY solutions, increasing the numbers of pests.

Telford & Wrekin Council

spokesman Russell Griffin said: "

It is down to individual residents to decide whether to arrange for a professional service or to tackle the problem themselves.

"However, if they ask for assistance via the council, they can rest assured that we will provide a prompt, effective and professional pest control service."