The bumblebee is frequently mistaken for the honey bee

Intensive agriculture and a decrease in the number of insect-pollinated crops have led to a drastic decline in bumblebee numbers over the past 70 years, they said.

With fields turning into poor homes for bumblebees, gardens are an increasingly important habitat for them.

"Without wild bees our gardens would be sterile places but we do not always give enough thought to how we manage our gardens to encourage these beneficial insects," said Fiona Reynolds, director-general of the National Trust.

The bumblebee Most bees are solitary 80% of the food we eat comes from crops pollinated by bees 25% of Britain's 250 wild bee types are rare or threatened with extinction Some species have declined by as much as 60% since the 1970s There are 24 species of bumblebee in Britain Three bumblebee species and at least seven other bee species have become extinct in the last 150 years

"Every garden counts in the wildlife stakes, whether large or small, urban or rural. With over 15 million gardens across the country, gardeners collectively can make a huge difference," she said.

English Nature and the National Trust say many gardeners mistakenly think all flowers are good for bees, when in actual fact, many modern hybrids are sterile and do not carry pollen to attract the bees.

Bumblebees are also wrongly thought by some to be aggressive, usually because they are confused with wasps and honey bees.