Bed bugs warm to London

London has become a "perfect breeding ground" for bed bugs, experts warn today. The average bed could harbour up to 1.5 million of the mites, which can trigger asthma and allergies.

"London is a real hotbed for dust mites," said Marcella Ucci of University College, London, who is studying them on a Governmentfunded project.

"The recent warm temperatures and humid conditions mean that mite populations are expanding rapidly.

"We think that by 2050, throughout the South-East, populations will have increased by up to

eight times." To make their predictions, researchers use a combination of computer models and live mites.

They create "pockets" of a few hundred mites in a sealed envelope in 40 volunteers' beds. By altering heating and even room design, the team monitors how well the mites cope.

"Our initial results show the key is humidity but we have a long way to go before we find out exactly how these mites spread.

"It could be, for instance, that taking your duvet off during the day helps, or even that bedrooms should be designed differently," said Miss Ucci.

Professor Stephen Burham of Imperial College said: "This is cause for concern. Dust mites are a trigger for everything from asthma to the 'year-round cold'.

"If you've got an old pillow, up to 10 per cent of its weight can be from dust mite faeces."