A Sting in the Tale by Dave Goulson

the Arctic Circle. As bumblebees overheat in warm climates, they did not spread far southwards towards the equator, which is why until some recent deliberate introductions there were no bumblebees in Australia, New Zealand or Africa south of the Sahara. About 20 million years ago bumblebees crossed from Siberia to North America, where they thrived and spread southwards. Eventually about 4 million years ago a handful of species moved down through the mountain chains of Central America to occupy South America, becoming the only naturally occurring bumblebees in the southern hemisphere.
    So now we arrive at the present day. The world is blessed with an extraordinary diversity of species of organism. About 1.4 million have been named so far, but estimates as to the true total vary hugely from 2 million to 100 million. Two hundred and fifty of the known species are bumblebees (members of the genus Bombus , of which twenty-seven occur naturally in the UK). There may be a few more yet to be found in remote regions, but probably not many. There are about 25,000 known species of bee (superfamily Apoidea , with 253 known from the UK), but many more undoubtedly remain to be discovered, particularly in the tropical regions. Bees in turn belong to the immensely successful insect order the Hymenoptera, which also includes ants and the wasps from which bees evolved, of which there are 115,000 known species. The Hymenoptera in turn are just one of many types of insect, collectively the most successful group of organisms on earth, with about 1 million named species, or about 70 per cent of all known species on earth.
    Until recently, this number of species was the highest it had ever been since life began. However, in the last few thousand years it has started to drop rapidly as man has remoulded the surface of the planet. As our ancestors spread out from Africa, many of the large mammals such as mammoths, giant sloths and sabre-toothed tigers swiftly disappeared, either hunted to extinction by man or driven to extinction because their prey disappeared. Most would have had no defence against groups of men hunting with spears and bows and arrows. At present, species are going extinct at somewhere between 100 and 1,000 times the natural rate, largely driven by habitat destruction and the ravages wrought by invasive species. It is estimated that one species goes extinct every twenty minutes.
    So far, only three bumblebees are thought to have gone extinct globally: Bombus rubriventris , Bombus melanopoda and Bombus franklini , but surely more will follow. It is the threat of extinction of large mammals such as tigers or rhinoceros that tends to capture the public’s attention, but arguably it is the loss of the smaller creatures that should give us most concern. Insects are responsible for delivering numerous ‘ecosystem services’ such as pollination and decomposition, and there is no doubt that little life on earth (including ourselves) could survive without them. As the famous biologist E. O. Wilson said, ‘If all mankind were to disappear, the world would regenerate back to the rich state of equilibrium that existed ten thousand years ago. If insects were to vanish, the environment would collapse into chaos.’

CHAPTER FIVE
    Finding the Way Home
    Pigeons are not everyone’s favourite creature. I must admit that I’m not enormously fond of the pestilential flocks of feral pigeons that infest many city centres, or even of the plump glossy wood pigeons that decimate my vegetable seedlings. Pigeons don’t look particularly bright – in fact I’ve always felt that they have a rather vacant expression, and they do an awful lot of mindless cooing – but nonetheless they are capable of truly amazing feats of navigation.
    Imagine this for a moment: you are locked in a dark box, transported for hours over 200 miles from home in a random, unknown direction, and then asked to find your own way back. You’d