SPIDERS are being used to wage war on deathwatch beetles in a green form of pest control at the Old Bodleian Library in Oxford.

The deathwatch beetles, Xestobium rufovillosum, were discovered in 1995, when the Old Bodleian, the oldest major public library in Britain, was being rewired.

Brian Ridout, of Ridout Associates, said that by using ultraviolet light traps to track the beetles they discovered that large numbers were being eaten by spiders - both the common house spider, found in baths, and the cellar spider, Pholcus pha- langioides, which also lives in roofs.

Mr Ridout said: "If you use pesticides to kill the beetles you also kill the spiders - and you won't kill all the beetles because a lot of the timber is inaccessible."

Contractor Linford-Bridgeman, of Litchfield, Staffordshire, says the deathwatch beetle infestation was caused by warm moist air from the library rising to condense on the cold underside of the copper roof. The damp provided an ideal environment for the beetles to breed.

The builders have now stripped the old copper roof to raise the oak timbers half a centimetre to create an air gap and improve ventilation, while keeping the spiders.

Mr Ridout said: "If you control the numbers of beetles by improving the atmosphere, a few hundred spiders will probably keep them in check. Actually introducing spiders may be the next stage, if we can catch enough."

The university is spending £6.5m over three years to repair, refurbish and modernise the library, whose oldest section, the Duke Humfrey library, dates back to 1488.

New window blinds and film will be put in to protect ancient manuscripts from the sun, and conservation work will be done on the 400-year-old painted ceiling.

At the same time, all readers' desks will be linked to the university's computer system and fibre-optic lighting will be installed.

Story date: Friday 05 March

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