Nature 2012 June

It’s a jungle out there

There is much we can thank the Victorians and Edwardians for and much perhaps we rightly choose to forget. A major preoccupation with both Victorian and Edwardian gentlemen and indeed many ladies too, was collecting all forms of our native wildlife.

A visit to Walter Rothschild’s Museum (now part of the National History Museum) will confirm what happens when such an obsession gets out of hand. The museum has more stuffed birds, reptiles and mammals than you can shake a stick at and cabinets full to the brim of pinned and mounted arthropods (insects, arachnids etc). Within this menagerie are species from around the world once common, some now extinct and others at risk of the same fate.

Both the Victorian and Edwardian collectors are responsible for giving names to much of our native animals and plants. At the time, animals from the four corners of the British Empire and even more remote foreign parts were being displayed in museums and zoos, such as the then newly opened London Zoo. So it is no surprise that amateur naturalists and collectors such as lepidopterists (butterflies and moths), coleopterists (beetles), arachnologists (spiders), were tempted to coin a name for newly discovered domestic species which bore some passing resemblance or unusual characteristic feature to one of these exotics.

Far as we might be from the African savannahs, the South American rainforests or Indian jungles, we have a menagerie of animals living within or visiting our gardens and native to the Chilterns. Like the distinctive quadruped which roams the African grasslands, we have an unusual arachnid in our gardens, patios and brick walls called the Zebra Spider: so called because it has distinctive black and white horizontal stripes along its body. It is one of a small group of arachnids in the country that do not produce a web. Instead, it relies on two very large eyes (part of a set of eight). These enlarged ones provide binocular vision to hunt down and capture prey. Food comes in all shapes and sizes from greenfly to small beetles. Catching small insects which can travel at considerable speed requires more than a sharp pair of eyes. To overcome this, the zebra spider has evolved a set of eight powerful legs to leap over 16 times its length and pounce on its unsuspecting meal.

It is not only appearance that suggested names to erstwhile enthusiasts. The behavioural characteristics provided suggestions: like the Elephant Hawk-moth, which can be found locally. Moths, like Butterflies, have four distinct stages in their development and it is the larval stage that the elephantine features come to light. One of the common food-plants of this insect is willowherb. This plant flourishes in recently disturbed ground and was a common site on bomb sites during and after the Second World War. In Victorian Britain the rapid construction of the railway network led to an equally rapid spread of the crimson- flowered plant along these causeways and must have also resulted in an explosion in the numbers of this moth species.

As a small caterpillar the elephant hawk-moth is susceptible to predation by birds, so it is unsurprising that in its early stages of development it has a fairly nondescript lime green colouration. However, having reached a size which affords it some protection from attack, the caterpillar’s camouflage is exchanged for more strident hues. The larva also strikes two poses. First, one described as a ‘snakes-head’ shows off false eyes which mimics a small snake when disturbed and a second, by extending the front-end of its body, was seen as similar to an elephant’s trunk. The fast-flying moth, seen on the wing on warm evenings, is a spectacular powdered-pink in colour.

We are familiar with dragonflies and their close relatives the damselflies. However, although not possessing the delicate beauty of either of these, there is a similar but unrelated large flying insect. It is not the flying adult of this species but its larva which is of particular interest and is responsible for the unusual name of Ant- lion. This diminutive animal lives out this stage of its lifecycle typically at the bottom of a sand pit of its own construction. Such is the construction of the pit, with steep sides coming to a point at the base, that the Ant-lion’s unfortunate prey, ants, lose grip and fall over the edge of the pit and into the grip of the predator’s lethal sickle-shaped jaws. The prey is then injected with lethal venom.

We are blessed with some interesting ponds in the Hilltop Villages. Not just the two on Cholesbury Common but notable others are to be found at Braziers End and on the road verges of Oak Lane and Bottom Road. Some of these may be ‘perpetual,’ like the Bury Pond in the Hill Fort, some seasonal and probably suffering to some degree to the current drought conditions. Despite this there are interesting flora and fauna to be found in them.

There are a number of carnivorous beasties, but to keep to the theme of this piece I have opted for the Water Scorpion. Like the Ant-Lion this is a quirky-looking insect. Swimming is not one of its strengths and without gills it needs to surface periodically to take on air through a thin whip-like siphon tube at the base of its abdomen. Although it might crawl out of the water and, like other water-bugs, has wings, it cannot fly: instead it uses them to trap oxygen-rich air. To aid movement, both through water and through the tangle of weeds, it has a much flattened body shape and looks like a dead leaf, which affords some disguise and protection from predator fish or ducks. It spends most of its time crawling along within the muddy zone at the bottom of ponds or ditches. Its front legs have been adapted to catch, with a scissor-like action, other insects and also tadpoles as well as any invertebrates.

Recently, examples of tropical scorpions have also been found in this country. Like other alien species they were first found near dockland. Able to survive very cold temperatures, they arrived onboard vessels carrying fruit and vegetables and escaped into the often wild hinterland around docks and harbours. As far as I am aware there are no zebras, elephants or lions currently roaming wild in the UK!

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