The spider has not been spotted for several weeks

Jan Price and son Wayne, from Gorlas, Carmarthenshire, Wales, say the spider will cast a shadow over festivities.

One theory is the spider - described as the size of a CD - has wandered into the house from a nearby property.

Mrs Price said her son first spotted the spider when he was watching TV in his bedroom in November.

A week later Mrs Price saw the spider herself while tidying the house.

"I thought something had fallen from the dresser but when I went and had a look, I saw what looked like a massive ball of grey wool running from the radiator underneath the bed," she said.

"It was not a normal spider - it was the size of a CD."

The sighting prompted angina-prone Mrs Price to move out to a friend's house, while Wayne, 24, went to his girlfriend's.

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Local snake and spider expert Geraint Hopkins placed traps baited with locusts in the semi-detached house to snare the spider.

But the unwelcome visitor - thought to match the description of a Chilean Red tarantula - has not been seen since the start of the month and the family have returned home.

My daughter is coming back for Christmas but will be staying over Jan Price

Mrs Price is against fumigating the house as the spider's remains could stay hidden.

She can not relax until it is carried out of the house "dead or alive".

No-one has come forward to claim the tarantula and it has led to calls for a register on people keeping exotic animals.

"The friends that do call at the house these days look at the floor when they talk to you," Mrs Price said.