Numbers have soared in recent weeks after the warm early autumn triggered a breeding frenzy.
Experts have warned people to stay away from the poisonous creatures after a spate of bites left victims in hospital.
Scientists say the colder weather forecast for the next few weeks will drive the creatures into warm homes.
We told yesterday how Simon, of Newport, Monmouths, was left with a gaping wound in his leg and still needs crutches.
In October eight-year-old Abbie Kinnaird of Colchester, Essex, was bitten on her hand by what is believed to be a false widow and needed a skin graft.
John Tweddle from the Natural History Museum said: “We’re expecting the species to continue to increase.”