Nature 2017 october

Beætle mania

The explosion onto the UK pop scene of the early 1960s of the ‘Fab Four’ brought about ‘Beatle Mania’. This was not the first time the UK had experienced such fanaticism. There had been an earlier outburst of ‘Beetle Mania’, this time in the early 19th century, when gentlemen of leisure engaged in a fanatical search for interesting, unusual and rare examples of beetles.

For Charles Darwin it progressed to passionate interest in beetle collecting or ‘beetling’ as it had by then become known. By the end of summer 1828 Darwin knew he had found a new vocation, as a naturalist. Through his obsession with beetle collecting Darwin became fascinated by the almost inexhaustible variety of shape, size, colour, and above all the habits of this very large family. Darwin later remarked it had been this almost in nite diversity of beetles which provided the germ of the idea that was to become an important building block underpinning his theory of evolution through natural selection.

Beetles have been around for over 300 million years. The secret of their longevity is believed to be their ability to survive global disasters and the speed of their evolutionary adaptability to take advantage of new habitats. Worldwide, beetles are by far the largest group of insects. With an estimated 400,000 so far classified, the actual number of beetle species could be at least double this. So much of the tropics, where most have so far been found, remain unexplored that some entomologists have put the number as high as 8 million.

In the UK there are 4,000 or so beetle species. By Darwin’s time nearly all had already been identified. The smallest is not much bigger than this full stop. The largest is the mercurial stag beetle. The relatively small number of British beetles is due to the temperate climate we find in the British Isles. And despite beetles being found in every habitat, they are vastly outnumbered by other insect species, such as wasps and flies.

I came across this pithy quote from art critic and author, the late AA Gill, perhaps providing a clue why those Victorian gents were so fascinated by these bugs…

“Beetles… are not aristocratic, vain or esoteric, like butterflies and moths, or communists like ants and bees. They are not filthy, opportunistic carpetbaggers, like fiies. They are professionals, with a skill. They’re built for a job. And get down to it without boastfulness or hysteria. And there is nowhere that doesn’t, sooner or later, call in a beetle to set up shop and get things done.”

To illustrate the sentiments of Mr Gill what follows are examples of the diversity of just some of the beetles that can be seen around here…

One of the largest groups, and the most often seen in our gardens, are the ground beetles. Though many are predominantly black they can still be distinguished by their particular metallic iridescence or characteristic habits, like the Violet Ground Beetle, which everyone will be familiar with as it is the one that you see scurrying across the patio or the living room carpet! Others are identifiable by their methods of defence: for example, the Bloody-nosed Beetle. When distressed or molested by a predator its mouth and body joints exude a drop of blood-red fluid which is noxious enough to warn off and enable escape. In a similar vein the eponymous Bombardier Beetle fires out a foul-smelling scalding liquid accompanied by a sharp popping sound, the result of a chemical interaction not dissimilar to that contained in an incendiary weapon.

The Dung or Dor Beetle processes animal manure. ‘Dor’ is old English for slow and dim-witted. Despite its lowly status in the hierarchy of the coleoptera we should honour their vital role in consuming their own weight of animal waste product, thus removing on a global scale more of that manure from our planet’s surface than any other natural process.

The Cockchafer is perhaps the best known. That bumbling character we find drawn to outfacing lighting in May. Its anonymous-looking larvae spend two or three seasons underground munching on grass or cereal roots. Not the best of advocates for the beetle clan.

The Whirligig Beetle spends its adult life in a perpetual spin, skimming around on the surface of ponds, feeding on yet smaller insects that have fallen in and are trapped on the water surface. Their eyes are divided horizontally with the top half keeping watch above and the lower one beneath the water, both places where predators also lurk. The Great Diving Beetle lurks there also but the whirligigs are safe as this behemoth is a fierce carnivore of goldfish, frogs and newts.

The Glow-worm stands out both in comparison to other beetles and literally through its illumination. The story goes they were once so common you could read by their light! They are still to be found in the Chilterns. Only the adult females emit a golden-green pulse at night to attract males, whose eyesight is tuned in to spot them. Poets from Pliny to Shakespeare, Blake to Coleridge have all praised their spell-binding attraction and star-spangled qualities lighting the way home.

The Stag Beetle had a reputation in Norse mythology as a favourite of Thor and can summon thunderstorms. It is Britain’s largest beetle and very much one of the flag-bearers for insect conservation. The ‘antlers’ of the male are reserved for demonstrating its prowess during ‘rutting’ encounters with other males and possibly courtship with the female. Aside from this, most of the time is spent exploring tree trunks in search of rotten wood.

During Darwin’s voyage on HMS Beagle while in South America he discovered a new species of giant stag beetle which now bears his name. This giant has ‘antlers’ that are much longer than the rest of its body. Darwin pondered for a long time why such extravagant equipment was needed. Recounting the ‘rutting’ stag beetles of his beetle-collecting days he reasoned that from one generation to the next only those stag beetles with the largest ‘antlers’ had succeeded over less endowed rivals in winning the favours of choosey females. His theory of sexual selection and its application to most animals, including humans, remained hugely controversial for most of the 20th century and is still a matter of debate and dispute by some today.

That sums up what catching the ‘beetle mania’ can do to you. Short of such fanaticism however there is some enjoyment to be gained around and about here from identifying the common species of larger beetles. In our gardens and houses, they can be appreciated too. With minimal exceptions beetles are our friends, preying as they do on the unwanted pests.

That is all for this time. Comments and questions always welcome to ChrisBrown@rayshill.com