The ladybird is the farmer's friend

The campaigners, the Wildlife Trusts, say in a report, Beauty and the Mini-Beasts, that invertebrates perform a vital role for all the natural world.

Ladybirds, for example, eat aphid pests, and soil fertility depends on the activity of worms.

Some flying invertebrates are found in high numbers in the UK. About a quarter of the world population of southern damselflies is found in Britain.

Four cms long, they spend two years as larvae to enjoy an adult life of two to three weeks.

They need a watery habitat, but land drainage and changes in land use have cut their numbers by 30%.

Shopping list

The Trusts say it would take about �55,000 to pay for three years of work on stabilising damselfly numbers and making sure that no further sites are lost.

They have a list of other species whose rescue they have costed:

• �65,000 for the mire pill beetle
• �35,000 for the narrow-headed ant
• �30,000 for the black bog ant
• �10,000 for the "Suffolk" leaf beetle.

Caterpillars: Short on charisma, long on potential

The Trusts' director general, Dr Simon Lyster, said: "More than 150 species of invertebrates have become extinct in the UK in the last two centuries.

"Now they need our support more than ever. Mini-beasts are an intrinsic part of the web of life, as deserving of our attention as the otter or the red squirrel.

"Modest funding could make a huge difference and, coupled with a wider recognition of their needs and a greater co-ordination of effort, we can ensure the future of some of our most weird and wonderful biodiversity."