Extreme Insects. Richard Jones

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СКАЧАТЬ that nothing in nature is that straightforward. The common seven-spot always has seven spots, but the closely related ten-spot ladybird, Adalia decempunctata, very rarely has ten. In fact it can have anything down to no spots. It can be red with black flecks, black with yellow shoulder marks, chequered, netted, speckled or barred. When early naturalists put Linnaeus’s binomial system into use, they went to town with ladybirds.

      There was sexmaculata and sexpunctata for six-spotted ones; octopunctata had eight spots, quadripunctata four; semicruciata was halfway to having a cross on its back; semifasciata had half a stripe; centromaculata had spots down the middle; triangularis had three marks; subpunctata had small spots; obscura was obscurely marked. There was only one small problem – all these were the same species.

      There are over 80 different named forms of the ten-spot ladybird, many once thought to be separate species, but now recognised as one species featuring different genetically controlled colour patterns. Geneticists are still trying to work out how these patterns are controlled at the level of the genes and the DNA.

      These are not races or subspecies, where particular colour-ways occur in discrete geographical zones or different places around the world. The different patterns often occur together, and in breeding experiments many different patterns can appear in the offspring of identical ‘normal’ ten-spotted parents.

      One selection pressure that can drive the evolution of a diversity of forms is the presence of predators that hunt by favouring one precise colour-way. Birds, in particular, hunt using a ‘search-image’ in their brains, seeing targets that match the image but missing others that look slightly different. By having many different patterns, at least some individuals should survive to reproduce. The only trouble with this theory in this case is that all ladybirds are brightly coloured to remind birds not to eat any of them because they taste horrid. Quite why the ten-spot ladybird should have such versatile patterns is still open to debate.

Bloodiest insect

NAME	bloody-nosed beetle Timarcha tenebricosa
LOCATION	Europe and Central Asia
ABILITY	deliberately spits out its own blood

      Insects defend themselves from attack in many different ways. After hiding, possessing a weapon is one of the commonest strategies. The weapon may be biting or stinging an enemy, but it may also be simply tasting foul. Plenty of plants contain noxious chemicals to deter herbivores, and plant-feeding insects can take advantage of this fact by storing the poisons in their bodies.

      There is one drawback for the individual with the poisonous body. Although birds (the main insect predators) may soon learn to avoid a particular species because it tastes disgusting, that is a bit late for the individual insect they have picked up, crushed, chewed and swallowed, even if they then vomit it back up again. It would be much better if the insect could warn of fits potential predator by giving it a taste of what might come should the meal be fully consumed.

      This is exactly what many beetles do. Rather than wait until their innards are squashed out in the bird’s beak, they defensively squeeze out large droplets of their foul-tasting haemolymph (blood). As soon as the bird tastes the bitter chemicals, it spits out the not-so-tasty morsel more or less unharmed.

      The commonest beetles to use this defence, called reflex bleeding, are ladybirds, which exude droplets of their yellow body fluids from special pores in their knee joints. The most spectacular, though, is the aptly named bloody-nosed beetle, Timarcha tenebricosa, which oozes out a great drop of bright-red liquor from its mouthparts.

      Ladybirds are brightly coloured to emphasise the warning. Timarcha is a sombre black, but its colouring is equally obvious against the green of its meadow foodplants. This large, lumbering flightless leaf beetle has little to fear from predators and it feeds quite happily in broad daylight.

Most beautiful insect

NAME	birdwing butterfly, in particular Wallace’s golden birdwing Ornithoptera croesus
LOCATION	Batchian (Bacan), Indonesia
ATTRIBUTE	beautiful enough to cause one of the world’s most hardened travellers nearly to faint

      Beauty is very much in the eye of the beholder; just look at some of the names cooked up by entomologists. Scientific names regularly include terms such as formosa (handsome), splendidissima (most splendid), pulchrina (beautiful), nobilis (noble), venustus (lovely) and elegans (elegant).

      There are many insects worthy of the title ‘most beautiful’, but nowhere is this better described than in the words of Victorian naturalist, scientist and traveller Alfred Russel Wallace. In a time before research grants, Wallace financed his travels by making collections for wealthy patrons or selling the handsome and strange specimens when he returned home to Britain. The highest value specimens were fabulous birds of paradise and beautiful birdwing butterflies. He knew only too well the worth of his collections. On the morning of 6 August 1852, during his return across the Atlantic from South America, the ship on which he was travelling, the Helen, caught fire and sank. Wallace and the crew spent nine days in the open life boats before they were rescued, but all Wallace’s specimens were lost.

      Undeterred, he published his Travels on the Amazon and Rio Negro and was soon off exploring and collecting in Southeast Asia. He managed to bring his booty home safely this time, and captured the essence of exploration, discovery and the hunt for fantastical beasts in Malay Archipelago, published in 1859. On his first venture into the forests of Batchian (now Bacan), one of the Mollucan islands of Indonesia, he caught sight of a spectacular birdwing butterfly. It took him a further two months to finally collect a specimen. Wallace later named it Ornithoptera croesus, after the 6th-centuryBCE king of Lydia (now part of Turkey) famed for his wealth. Wallace’s words still resonate today:

      ‘The beauty and brilliancy of this insect are indescribable, and none but a naturalist can understand the intense excitement I experienced when I at length captured it. On taking it out of my net and opening the glorious wings, my heart began to beat violently, the blood rushed to my head, and I felt much more like fainting than I have done when in apprehension of immediate death. I had a headache the rest of the day, so great was the excitement produced by what will appear to most people a very inadequate cause.’

Longest head

NAME	giraffe-necked weevil Trachelophorus giraffa
LOCATION	Madagascar
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