Extreme Insects. Richard Jones

of size by record-measuring organisations. As a result, four other beetles are contenders for the title. These are the shorter but stouter ‘Elephant’ beetles from South America – Megasoma actaeon (13.5 cm) and M. elephas (13.7 cm) – and the Goliath beetles from Africa – Goliathus regius (11 cm) and G. goliathus (11 cm).

Longest insect

NAME	Phobaeticus chani
LOCATION	Borneo
ATTRIBUTE	greatest length in body and legs of any insect

      One of the best ways to avoid being eaten is to hide, and one of the best ways to hide is to blend in with the surroundings using camouflage. Stick insects (also called walking sticks) have taken this to an extreme, and their pencil-thin bodies and pin-thin legs perfectly resemble the twigs through which they climb. So good at hiding have they become that some stick insects have acquired a trait that is a common evolutionary result of having no (or virtually no) predators – they have become very large.

      For nearly 100 years, the record for the longest insect in the world was held by a specimen of a giant stick insect from Borneo, Phobaeticus (formerly Pharnacia) kirbyi. Its body was 328 mm (12.9 in) long, and from the tip of the outstretched front leg to the end of the back leg it measured 499 mm (19.6 in). This specimen had long been misidentified as the closely related P. serratipes, and it was only shortly after its true identity was established in 1995 that another huge stick insect was discovered. Ironically, this time it was a specimen of the true P. serratipes, found in Malaysia. It had a total length of 555 mm (21.9 in), although its body alone was slightly shorter than the famous P. kirbyi specimen.

      Measuring lanky insects is fraught with difficulties, and this could have been the point at which some controversy arose. Most size measurements for insects deliberately ignore legs, antennae, tails and snouts because they vary tremendously within a population, especially between male and female of the same species. It has long been known that the leg lengths of stick insects vary, even when measured on different sides of the same specimen. However, the matter was settled in October 2008, with the description of a new species of stick insect from the Malaysian state of Sabah on the island of Borneo. Phobaeticus chani was named after the entomologist Datuk Chan Chew Lun, who donated the largest of three specimens, found by a local collector, to the Natural History Museum in London. With a body length of 357 mm (14 in) and a total length of 566 mm (22.3 in), it takes the record no matter which way it is measured.

Whitest insect

NAME	Ghost beetles in the genus Cyphochilus
LOCATION	Southeast Asia
ATTRIBUTE	the whitest covering of any insect

      White is not a common insect colour, as it makes an insect stand out to predators in a natural world dominated by browns and greens. Perhaps the best-known white insects are cabbage whites (Pieris species). Like other butterflies, they use their colour patterns to recognise each other when mating. But they fade into insignificance against ghost beetles in the genus Cyphochilus.

      Ghost beetles are found throughout Southeast Asia, where they are sometimes regarded as a pest in sugar cane plantations. Ghost beetle larvae feed in fungi, and the beetles’ whiteness is thought to be a camouflage against this rare white foodstuff. On close examination, the whiteness is caused not by the beetle’s exoskeleton (its tough outer shelllike body), which is dark brown and almost black, but by a dusty coating of pure white overlapping scales, which cover its body, head and legs. Each scale is minute, measuring only 250 by 100 μm and just 5 μm thick (a μm or micrometre is one thousandth of a millimetre).

      The scales were first studied by Pete Vukusic, an optical physicist at Exeter University in the UK, who discovered that the beetles’ whiteness is caused by a random network of tiny filaments, 0.25 μm in diameter, inside the scale. The random arrangement of the filaments means that the different rainbow colours in natural white light are scattered simultaneously, equally and highly efficiently, with no single colour predominating. The beetles are among the whitest objects found in nature – much whiter than teeth and milk.

Shiniest insect

NAME	golden chafers in the genus Plusiotis
LOCATION	Central and South America
ATTRIBUTE	appear to be wrought from burnished gold and silver

      Insect colours serve many purposes. Greens and browns act as camouflage against living and dead leaves, tree trunks, branches and twigs. Bright yellow, orange and red, often marked with black, warn that an individual is poisonous or might sting. But the brightest and most spectacular colours do neither. Metallic glints of bronze, blue, green, red and violet occur in many beetles, bees, wasps, flies and, of course, butterflies (see page 48). The most astonishing of these are the brilliantly shining golden chafers, Plusiotis species, of Central and South America.

      Metallic sheens are not colours in the conventional sense of a pigment or colourant on the surface of the animal. The red of a ladybird, for instance, appears because the yellow, green and blue wavelengths in sunlight are absorbed and only red light reflects back into the eye of the beholder. The metallic shine of the golden chafers, by contrast, is caused by the white sunlight being broken, much as it is when shining through a diamond, to give a series of rainbow glints.

      Seen through an electron microscope, the surface of the beetle is revealed to be covered with minute parallel grooves. These reflect certain portions of the light at the precise angle to shine like polished metal, while absorbing and scattering other wavelengths.

      Shining colours are not just for showing off to a potential mate, although this is important for many butterflies. One of the main purposes, ironically, may be to avoid attention. In bright sunlight, against wet mud or in the dripping rainforest canopy, metallic glints are surprisingly confusing to the eye of a predator, which searches for images based on shape.

Slimiest insect

NAME	fungus gnat larvae in the family Keroplatidae
LOCATION	worldwide
ATTRIBUTE	create mucus webs to collect their food

      Contrary to popular opinion, insects (like snakes) are not slimy. Slime or, to give it its more technical term, mucus, is a sticky