THEY EAT CLOTHES, CURTAINS AND CARPETS, THEY bore holes through chairs, beds and floorboards, and they nibble at the pages of books. And, thanks to global warming, they are on the march.

The rising temperatures and increasing humidity triggered by climate change are threatening to unleash a plague of pests on the priceless contents of Scotland's historic buildings, according to a new warning from the National Trust for Scotland (NTS).

Clothes moths, carpet beetles, woodworm, mould and fungi are all on the ascendancy, says NTS's head of collections conservation services, Clare Meredith. This puts the textiles, furniture and books in some of the nation's iconic castles and stately homes in danger.

"There is a shift, an increase and a change in diversity of different pests and they are coming our way," she told the Sunday Herald. Warmer weather was enabling new species of carpet beetle to move north and encouraging more woodworm infestations, she said.

"Once a carpet beetle starts munching, the damage is irreversible and the carpet's gone," warned Meredith. "Clothes moths used to have one breeding cycle a year, but now we are seeing two or even three a year."

The growing activity of moths had recently caused NTS repeated problems in its old farm houses at the National Museum of Rural Life at Kittochside near East Kilbride, she said. Clothes had been holed and damaged.

Many of NTS's 129 historic properties contain irreplaceable fabrics, such as the mid-19th-century carpet in the drawing room of Brodie Castle in Forres. At Castle Fraser in Inverurie, a late 18th-century four-poster bed is adorned with beautiful red embroidered curtains.

The library at Haddo House near Ellon contains an imitation oriental chenille carpet made in about 1880 by the famous Templeton carpet factory in Glasgow. There are also some wool curtains dating from about the same time hanging in the library.

Bob Child, pest adviser to the National Trust for England and Wales, endorsed Meredith's fears. He pointed out that Guernsey carpet beetles, originally from the Channel Islands, had now been found close to the Scottish Border and were "gradually creeping north".

Warmer, wetter weather also helped silverfish and species of lice that can consume the pages of books, he said. "The pests are going to be coming in increasing numbers. Certainly woodworm are coming back."

Child, who is head of conservation for the National Museum of Wales, argued that rising temperatures not only boosted the breeding cycles of pests, but also made their eggs more likely to survive. In addition, it enabled them to fly further, causing infestations to spread more easily.

The government agency that looks after old buildings, Historic Scotland, has identified the increase in pests and diseases as one of the major threats from climate change. One of the key effects, concluded a report to the agency's board last August, was that "increased biological colonisation and insect attack will occur on the building fabric".

Across the UK, a survey of 130 managers of historic buildings by the Centre for Sustainable Heritage at University College London has uncovered widespread anxiety about the problem. Of those questioned in 2005, 54% said the risks posed by pests were of "great concern", while 23% said the risks were of "some concern".

As well as pests, NTS has identified a series of other threats to its properties from global warming. Increased ultraviolet radiation from the sun will cause paintwork on the outside of buildings to fade and crack sooner.

Rising water levels could bring a greater risk of damp to the cellars and ground floors of properties. This could be a particular problem at the 16th-century village of Culross on the Firth of Forth, where the water table is only about two metres below the houses.

The roofs and walls of historic buildings could be damaged by more rainfall, stronger winds and fiercer storms.

Heavy rain has already got inside the walls at Craigievar Castle in Aberdeenshire, causing the property to be shut so that the walls can be reharled.

According to NTS's head of buildings, Bryan Dickson, masonry itself was at risk of greater deterioration. "Increasing wet and dry cycles will increase the natural erosion of stone," he said.

Dickson stressed, however, that many of the problems could be prevented or managed by good maintenance. But increasing the frequency of inspections and repairs would cost more money.

NTS is a member of Stop Climate Chaos Scotland, a new coalition of more than 30 environment, development, faith, community and other groups with at least 1.5 million supporters. The coalition's recently launched campaign for tougher action to cut the pollution that is disrupting the climate is being backed by the Sunday Herald.

"The danger posed to old buildings is just one of the many reasons why we need to do all we can to tackle climate change in Scotland," said Dan Barlow, the acting director of WWF Scotland.

"The Scottish government must deliver a strong Scottish climate change bill. If Scotland is to achieve the 80% cuts in emissions by 2050, which the government is aspiring to, the bill will need to include statutory reduction targets of at least 3% year-on-year, and include emissions from international shipping and aviation."

Last week Catholic, protestant and Islamic faith leaders in Scotland came out in support of the demands being made by the Stop Climate Chaos Scotland coalition.

The Scottish government has published a draft bill to tackle climate change, which is out for public consultation until April 23.