A red mason bee mining mud

At the same time, intensive farming methods are threatening to wreak similar havoc on Britain's 254 species of native non-honey-making bees.

"Modern agriculture is not very bee friendly," said Dr Chris O'Toole, director of the bee biology unit at the Oxford University Museum of Natural History.

Mr O'Toole said the habitats preferred by many species of British bee were gradually being destroyed.

Missing hedgerow

Hay meadows that were home to wild flowers perfect for bees have been swapped for rye grass grown for silage.

Tractors can now cultivate every corner of a field leaving no place for logs and leaves to pile up that bees can use as nesting grounds. Other habitats are also under threat.

"Since the war we have lost 160,000 kilometres of hedgerow," said Mr O'Toole. "What remains is given a short-back-and-sides once or twice a year, so nest sites in hollow stems are destroyed."

This change in the landscape has already forced the extinction of the short-haired bumble bee (Bombus subterraneus) in Britain, and once widespread species such as the large garden bumblebee (Bombus ruderatus) are now on the endangered list.

Bee gardening

But suburban gardeners could provide a lifeline for some species of British bee. Mr O'Toole is working with the Oxford Bee Company to produce cheap nesting boxes for docile native bees to provide them with a home in suburbia.

A red mason bee entering an artificial hive

Some of the best habitats for bees are suburban gardens thanks to the diversity of flowers available to them, said Mr O'Toole.

The Oxford Bee Company has produced nesting boxes for the red mason bee (Osmia rufa), a solitary species that usually lives in hollow plant stems or beetle borings in dead wood.

Typically the female of the non-aggressive species creates a series of cells in the nest hole each one with an egg in it.

Wardens of the countryside

Each cell is sealed with mud, hence the name of the bee. The only pollen and honey it collects is to feed itself and to lay in a store for the emerging larvae.

The nest box is a stack of slim pipes that should attract bees when placed in a protected, south-facing position. Once established, red mason bees are likely to return every year and are proficient pollinators.

Gardeners buying the nesting boxes are likely to get a better crop from fruit trees in any garden the bees make their home.

Mr O'Toole said the plight of native British bees was starting to become more widely known and many farmers were now starting to do more to help species survive.

"We should start to regard, and perhaps reward, farmers for being wardens of the countryside," he said.