Insects: Little wonders too often overlooked

Sir David Attenborough will show us once again tonight why he is the supreme master of the art of observation. In his latest television series, Life in the Undergrowth, Sir David directs the spotlight on the tiny but numerous creatures that live all around us. These invertebrates - animals without backbones - are essential for the survival of all life on land and yet, as he explains, we are at best happy to ignore them and at worst we delight in swatting or poisoning them.

For many people, creatures with more than four legs - or none - epitomise the ugly or abhorrent side of nature. Apart from butterflies, dragonflies and the odd species of colourful beetle, the mass media has pandered to this perceived prejudice. Better to publish or broadcast pictures of fluffy birds or furry mammals than the satanic-looking images of insects, worms, slugs and spiders. Indeed, the BBC is said to have had an uphill struggle trying to convince some American networks that the series is visually palatable.

And yet these small creatures without backbones comprise 97 per cent of species in the animal kingdom. They have been around for 400 million years, about 100 million years longer than the vertebrate species. They also provide many of life's vital services, such as waste disposal and water purification, which we humans take for granted. Pollinating insects alone ensure that supermarket shelves continue to heave with fruit and vegetables. Invertebrates have also given us some of the finest natural products, from the sweetest honey to the smoothest silk garments.

Why, then, if these animals are so essential, so numerous and so important do we not take more interest in them? It was not always like this, according to the cultural entomologist James Hogue of California State University. "Throughout human existence, many insects have been admired for their ingenuity, beauty, fantastic shapes and behaviours," he writes in the acclaimed Encyclopaedia of Insects published by Academic Press. "In some instances, the use of insects as totemic figures that may symbolise ancestry or kinship of humans with these organisms leads to a deep sense of adoration and reverence."

The ancient civilisations of Egypt, Greece and South America were especially keen observers of these minuscule lifeforms. The Egyptians for instance saw the behaviour of the scarab, a beetle which rolls balls of dung across the ground to a burial chamber, as a messenger from the heavens. They saw the scarab as a symbol of the god Khepera who rolled the Sun across the sky each day. They also used it to represent the resurrected soul emerging from the body, which evidently came from watching new beetles coming out of the buried dung ball.

The Cochiti tribe of the American south-west constructed a creation myth around another beetle, Eleodes, which displays the habit of standing on its front legs and waving its abdomen in the air when it feels threatened. The Cochiti say the beetle was once given a bag of stars to distribute carefully in the sky. But the beetle was careless, spilling the bag into the Milky Way. Eleodes is now so ashamed that it hides its face whenever someone approaches.

Such charming mythology obviously came out of a very ancient tradition of quietly watching and contemplating some of the extraordinary sights and behaviours of the miniature world of the invertebrates. For all the apparent modern squeamishness attached to insects, spiders and other invertebrates, there is in fact a long history of being fascinated and awed by the planet's smallest inhabitants. Rather than give us mythology, however, Sir David provides a modern, scientific insight into the sheer drama and spectacle taking place every day at foot level.

"What is marvellous is how different they are from our behaviour," he explains. Some of the most complex and bizarre interactions in the animal kingdom can occur in view of our living-room windows - if only we could see. This behavioural diversity is because insects, spiders and the like have been around far longer than other land creatures and have evolved faster because they have such a high turnover in both numbers and generations. "So perhaps it's not surprising that they have developed relationships between one another of a complexity that blows the mind," Sir David says.

For the first time, for instance, Sir David's camera team has captured the extraordinary lifecycle of the alcon blue butterfly of central Europe which spends up to two years as a caterpillar living as a con artist inside an ants' nest. The butterfly's larva emits chemical signals that trick the nest's worker ants into believing that the caterpillar is in fact an ant larva in need of food, care and protection.

As if this story is not strange enough, a sound engineer working for the series has also managed for the first time to capture the caterpillar's grunt-like cries, inaudible with conventional sound recorders. And to add a final twist, the fourth programme in the series captures the behaviour of the only creature that sees through the butterfly's con-trick. A species of parasitic wasp has evolved a trick of its own, by laying its eggs inside the ant-deceiving caterpillar.

Other visual firsts include the filming of a species of ant in the Mojave Desert of California, which carefully goes around blocking the entrance holes of a rival's nest before each dawn to stop its competitors from harvesting all the seeds in the neighbourhood. Meanwhile in Africa, Sir David is filmed next to a column of marauding Matabele ants who are about to attack a termite nest. The camera follows the resulting battle in close-up, blood-curdling detail.

Yet another ant species living in the Amazon jungle is shown injecting poison into the tips of any shrubs that dare to grow in its territory. The ant does this so that only its host tree, the Cordia shrub, grows in its territory, which can be the size of a football-pitch. Locals refer to these mysterious patches of monocultured land as "devil's gardens".

There were two moments in filming that especially delighted Sir David, a man not unused to delightful moments. One was the moment when a species of grasshopper or cicada in North America emerges from the ground after 17 years of drinking the sap of tree roots. "After 17 years the entire population emerge at the same time," Sir David says. "There are literally millions of them in the wood and all the males sing. The noise is absolutely deafening. You can hardly see a tree trunk between them. That's an extraordinary phenomenon."

The other awe-inspiring moment came after the camera crew had waited eight days for a species of mayfly to emerge from the Tisza river in Hungary. It rained constantly and a week passed with nothing happening. On the last day, however, the sun broke out and the sky filled suddenly with the tiny wings of mayflies. "We saw one and then within 20 minutes there were a million. They were so thick you could hardly see the opposite bank of the river. It was like a snowstorm," Sir David says.

Mike Salisbury, who produced the second programme in the five-part series, on how insects were the first land creatures to fly, explains that sensitive digital cameras and miniaturised lens technology were the critical innovations that allowed the filming of animals the size of a full-stop. In the past it was virtually impossible because natural light was poor and artificial light tended to fry them to a cinder, he says. Technology has revolutionised the filming of the smallest beasts. "You've got to get the lens down there with them," Salisbury explains. "We didn't delve into the library. We filmed everything new, to look for new aspects of the familiar."

One of the great aspects of Life in the Undergrowth is that it is not contrived. Salisbury insisted, for instance, that none of the flying insects would be tethered. This means that the amazing pictures of dragonflies hunting in flight and cascade damselflies darting in and out of a waterfall are absolutely genuine.

What better tribute could there be to a veteran broadcaster who has done so much to bring the wonder and awe of the natural world into the nation's living rooms?

'Life in the Undergrowth' starts tonight at 9pm on BBC1