Transcription
There are some animals that have four lives. The first as an egg.
Their eggs come in many shapes and sizes and after only a few days they hatch into an equally bewildering variety of caterpillars. No matter how colorful or bizarre, small as pinheads or 8-in giants, all caterpillars must function as eating machines because they will spend the next stage of their life locked into a rigid case with no chance of feeding at all.
This chrysalis stage might last for months on end before it eventually produces a butterfly. Born to fly, butterflies wander through a wide variety of habitats, mostly in search of nectar from flowers. But not all. Some exotic species pierce fruit to drink the juice.
In Europe, moths sip the cream from milk. And the death's head hawkmoth finds honey irresistible, defying the defending bees.
Since ancient times, night-flying moths have been regarded as sinister. One tropical species is dangerous to humans, a genuine vampire that sucks blood and can transmit diseases.
But butterflies have always represented beauty and grace, symbols of reincarnation. Ancient legends called them the messengers of the gods.
The old Native Americans believed that the gods sent butterflies to earth to teach humans the meaning of perfect beauty. Even today, when we have named more than 150,000 species, they're regarded as the summit of insect evolution. The biggest of them have a wingspan of well over 10 in, gliding through the air like birds. Others hardly look like butterflies at all. The hind wings of the fragile plume moth are a fan of fine hairs. Often no more than a few millimeters long, moths are generally among the smallest members of the group. But then there's the Indo-Malayan Atlas moth, whose outstretched wings are more spectacular than the biggest butterfly. All moths and butterflies have one thing in common. They are very ancient creatures. Their ancestors fluttered around the dinosaurs, and their appearance today is unchanged after 50 million years. Much of the head is covered by dome-shaped compound eyes with 10,000 facets or even more depending on the species. In spite of this extravagance, a butterfly's eyesight is poor compared to that of mammals, though it is excellent at distinguishing fine shades of color. The oleander hawk moth, among others, finds its food by sight, selecting flowers principally for their colors. Some hawk moths have a proboscis more than 6 in long, allowing them to penetrate deep into flowers to find nectar. The special adaptations of moths and butterflies are as different as night and day, literally. Many butterflies unroll their proboscis only to drink the juices of fermenting fruits. They have to live exclusively on a liquid diet because the proboscis is a very narrow tube, up which the juices are pumped along a central canal formed by two parallel grooves. It's like a drinking straw. Insect like butterflies experience their world in a way that seems strange to us. Their sense of smell or taste is located at the tips of their antennae, which double as feelers, responding to touch and vibration to report on the condition of their surroundings.
Their most striking feature is their wings. Butterflies were once almost completely covered in hair-like bristles. They still have partly hairy bodies. In the course of evolution, the hairs on the wings became broader and flatter until they turned into scales. Tightly packed and overlapping like tiles on a roof, they cover the surface of the wing.
The glorious colors of butterflies come from pigments embedded in the scales, sometimes shimmering with iridescence to enhance the effect.
Here, too, there are exceptions. The tropical clearwing moths have lost nearly all their scales until their wings are transparent. Having the background visible through their wings is an effective form of camouflage, essential for such fragile and edible creatures. Plants do not open their flowers only when the sun shines. Some blossom at dusk or even at night. They attract animals that lead a double life, like the hummingbird hawk moth, which searches for nectar both by day and at nightfall. As the light fades, it moves from flower to flower, its wings beating more than 70 times a second, enabling it to hover like its namesake, the hummingbird.
The restless creatures of the night roaming apparently aimlessly through the darkness have given people the creeps since time immemorial. In the Middle Ages before windows were glazed, the spirits of the night came and went at will.
Often morning revealed only the lifeless corpses of those that had failed to find their way back to freedom.
One of the things attracting moths to human habitations was the smell of sour milk. In country homes in the old days, cream was left to settle overnight. On summer nights, uninvited visitors developed a taste for this human food. Once upon a time, country people thought they were witches that had adopted the form of flying insects in order to steal churned milk, in other words, butter. Hence the name butterflies, which once covered moths as well, though it's now used only for the day-flying members of the group. The witches that enter country kitchens at night are in fact mostly owlets moths or noctuids. It was not only scent that drew moths into buildings. Another powerful attraction was an open fire. Moths have always been mysteriously drawn to light. But the firelight was a snare. Once they got too close, there was no escape from it, and their delicate wings were fatally scorched. Animals that spoiled food by night or flew into the fire must have been emissaries of the devil. This was how everyone saw moths in the superstitious depths of the Middle Ages. Moths were even believed to have the power of life and death in those benighted times.
As the family watched at the deathbed of a dying relative, all the terrors of the night were close about them, and religion fought a losing battle with superstition. The sharp scent of perspiration drifting from the open windows was a powerful lure to passing moths. It was no accident that they often found their way in to quench their thirst with the nutrient-rich fluid. By medieval standards, this was conclusive proof that a witch had turned into a moth coming into the room to take the soul of the departed not to heaven, but out into the terrifying darkness of an everlasting night. But the rising sun signifies new beginnings, so that the butterflies, creatures of the day, were endowed with more positive attributes. Some were given mythical names like Apollo, after the Greek god of light and beauty. The butterfly shivers to warm up its muscles before basking in the greater warmth of the sun, symbolized by the glowing discs on its wings. An Apollo butterfly must reach a temperature of 30° C before it can fly. Many butterflies live in mountainous regions up to 6 and 1/2 thousand feet above sea level. In this cool climate, they often take a long time to reach flying temperature. In flowery meadows on the plains below, the butterflies are busy from first light. Peacocks bustle incessantly from flower to flower in their endless search for nectar. The swallowtail is even more active. It pauses at each flower for only a few seconds before moving on to the next. Some butterflies have different tastes, ignoring nectar in favor of animal carcasses. The purple emperor, along with a few other species, prefers this somewhat grizzly diet. The liquid it collects contains salts that the butterfly needs to balance its metabolism, rather as the moth gathered sweat from the dying man. Strange as this feeding behavior might seem, it can be found in any summer meadow. There's nothing odd to our eyes about swarming bees. From the earliest times, humans have taken advantage of their ability to make honey. The artificial hive offers the bees safe housing, and the beekeeper a chance of easy access to combs full of honey. The hive also offers the bees protection from their enemies. But from time to time, a raider in a distinctive dress visits the beehive, the notorious death's-head hawkmoth, a long-distance flyer that can reach Central Europe from its African homeland. Now, at the end of its journey, it rests on the trunk of a fruit tree, perfectly camouflaged as it dozes the day away. When afternoon comes and the light fades as the shadows lengthen, the time has come for it to go about its business. Often it's late at night before the death's-head starts shivering to warm up.
Eventually it lifts off in search of only one thing, honey. It's acute sense of smell guides it to its target. As the scent of honey becomes more intense, the moth becomes more excited. It heads directly for the narrow openings of the hive and squeezes in. The most dangerous part of the raid is ahead. The death's head must climb up to the honeycombs surrounded by belligerent bees. With its short proboscis, it punctures the lids of the honey cells to steal their contents. The bees put up a spirited defense of their stores. The moth's warning sounds are no use to it here. At length, it's brought down fighting for its life. The bees swarm to the spot to attack the robber with their stings. Not all the moths manage to escape. Many of them fall victim to the bees' superior forces. In the end, even such a sturdy animal as the death's head has no chance of surviving the fusillade of stings. This is the harsher side of nature. The search for food may involve the risk of death. Over millions of years, moths and butterflies all over the world have evolved into specialists in survival. Camouflage is one way, and another is threat. Round markings on the wings remind potential enemies of the staring eyes of a mammal.
Eye spots are used by many species to a greater or lesser extent. The peacock issues a four-eyed warning. In early summer, the woods are home to another species that uses a similar strategy. It's the eyed hawk-moth, active by night and resting during the day. Others of its woodland neighbors are active by day, hunting. Like great tits collecting insects for their young. Although the moth clings closely to the tree trunk, it doesn't escape the sharp eyes of a hungry tit. The bird scrutinizes it from all sides as a potential meal. It seems disconcerted that it doesn't try to get away. Eventually, it tries a tentative peck and triggers the eye spot reaction. Now it's even more disconcerted at the glaring pink-rimmed eyes on the moth's hind wings. The moth rocks rhythmically, mimicking the movements of a mammal's head, which is highly effective. Finally, the transformation from moth to monster has the desired effect. Moths and butterflies are not only masters of camouflage and bluff, many of them are poisonous or taste so foul that no bird would ever hunt them. But even they have enemies. The praying mantis seems to be immune to most poisons. Even lacewings, generally considered inedible, are on its menu. With jerky movements imitating a leaf moving in the breeze, the mantis creeps closer and lies in wait. It keeps its huge eyes fixed on the unsuspecting drinker. When the mantis strikes, there is no escape. Eating and being eaten, it's an inevitable part of the natural world, even for toxic butterflies. Soon, there will be nothing left but a few colorful rags of wing. In the rainforest, large luxuriant flowers are found only in clearings, islands of sunlight that attract many forest animals, not only hummingbirds. A vast variety of butterflies flutter around the blossoms or fight for territorial rights in the glade. But to rest, even for a moment, is to invite danger. Pouched tree frogs love to bask in the sun. And they have a hearty appetite for anything edible at any time. Like most climbing frogs, they're expert at catching quick-moving prey. Within seconds, the butterfly is folded up into a bite-sized morsel and disappears inside the frog. In spite of their legions of natural enemies, the butterflies stay ahead of the game by sheer fertility. The females secrete airborne scents attracted to their own species called pheromones, which the males are literally unable to resist. Like hormones in the blood, pheromones directly affect the male's behavior. Quite often, the lure brings in several suitors for one female. They can't all win. In the end, only one succeeds in mating. Male moths often have large, elaborate antennae like huge cones, the better to sample the air for the scent of a receptive female as they fly. The antennae are so sensitive that they can detect and locate a female over a distance of several miles. A female Chinese giant silkworm needs to emit her characteristic pheromone for only a short time before she's joined by an amorous male. He wastes no time in climbing down the massive abdomen of his chosen partner in case a rival should appear at the last moment and challenge his right to mate.
All moths and butterflies all over the world breed by laying eggs.
They come in all shapes and sizes, a universe of color and form.
For all that, the biggest of them is barely more than a tenth of an inch long.
Among the biggest eggs are those of the Hercules butterfly of Papua New Guinea. The female is like an egg-laying machine. She has several thousand eggs packed into her swollen abdomen all needing urgently to be laid in the space of a few days.
Where there are butterflies, there must be plants to supply food for the next generation. But tastes vary, and butterflies are very choosy. Apollo, the messenger of the gods, feeds exclusively on stonecrop, a common plant in the mountainous areas where it lives. It lays a single egg on each leaf. It's a demanding task, and the female sometimes needs to take a break from her labors. But after a quick wash and brush-up, she carries on to the next plant. With more than 150,000 species of butterflies and moths, it's only to be expected that some of them lay their eggs in unusual forms, like these turrets. The turrets builder is a small, very common creature, the map butterfly. It lives all over Central and Southern Europe, mostly in meadows where nettles grow. The females, laden with eggs, settle on the underside of the leaves to set up their towers of offspring. The eggs are laid one on top of the other, and held together by a quick drying glue that the female secretes at the same time. Continually checking the condition of the leaf surface, she lays several turrets, each containing 10 to 15 eggs. The whole process takes about an hour. The eggs of some butterflies begin to hatch within a few days of being laid. Tiny caterpillars emerge, only a few millimeters long. They may be small, but they are very numerous. Some nurseries contain several hundred babies. The range of caterpillars is colorful and often bizarre, from the offspring of a taw emperor to the tropical relatives of the monarch. Some grow into giants within a few weeks. The Viennese emperor moth caterpillar can reach a length of about 5 in. A caterpillar's only duty is to eat, as much and as fast as possible. Some species use the plants they eat for more than food. The spurge moth, as its name suggests, feeds only on spurge, a highly poisonous member of the euphorbia family. This diet makes the caterpillar itself poisonous, a fact which it advertises with gaudy warning colors. The mullein moth also uses color to camouflage it on the bright petals of its food plant. For others, there's safety in numbers. Processionary moths always travel in a single file. Keeping in contact with each other in a long column, they give the impression of a single huge worm, which hardly anything will attack. Ermine moths follow the same principle, but without the same apparent discipline. They form chaotic communities of thousands, draping their untidy webs over the vegetation, and stripping every plant down to the last leaf, as though a swarm of locusts had passed by. Caterpillars are nothing less than eating machines, which can increase their weight a thousandfold, and eat out entire areas. But because their skin doesn't stretch, in order to grow, they have to molt. When this happens, the existing skin bursts open, revealing a new one underneath. Discarding the old outer covering is a laborious process, which most caterpillars will have to go through four times in their lives.
When it's done, the caterpillar is exhausted. After each molt, it takes a short breather before returning to its one and only task in life. The marathon meal must go on. The island forests of Hawaii, isolated from the mainland for millions of years, are the home of a very rare species of geometrid or looper caterpillar. Its movements give it its name. The leaves of the forest are no attraction to this species. It's a carnivore. Fruit flies, a couple of millimeters long, swarm in the virgin forest looking for rotting vegetation. Nearby, the camouflaged caterpillar lies in ambush, perfectly still. It waits patiently until a solitary fly wanders past. When the fly touches it, it strikes. It grips its prey with specially adapted forelegs, and its razor-sharp jaws do the rest. In most other parts of the world, caterpillars are hunted rather than hunters. Predators like the violet ground beetle roam the woodlands in search of prey. Caterpillars crossing areas with sparse vegetation are conspicuous and exposed to danger. The ground beetle does not miss such an opportunity. The struggle is short-lived. The thin skin of the caterpillar is no match for the beetle's powerful jaws, and it soon bleeds to death. The beetle crushes its body and sucks out the soft parts. Its meal complete, the beetle moves on in search of further prey. The cold staring eyes of a snake signal danger. It's best not to get too close. But this snake is an optical illusion. When the real head appears, the illusion is shattered. It's a tropical swallowtail caterpillar imitating a snake as a protection against its enemies. Most species of wasp are part of the army of caterpillar hunters. They need meat to feed their larvae. European relatives of the swallowtail rely on warning colors rather than camouflage with red dots to signal danger. Birds might take notice, but the wasp is not put off. But the caterpillar has another line of defense. It inflates an orange fork just behind its head and waves it at the wasp. The fork produces a pungent chemical deterrent. Even a hungry wasp with young to feed is driven off by the stench. In the endless natural round of hunting and being hunted, huge colonies of red ants are usually on the winning side. Hunting ants drag into each nest as many as 100,000 prey items every day, among them many caterpillars. There is no escape from the jaws of the workers and the efficiency of the system that transports the food home. Not all ants are carnivores. This small black species lives in large colonies, but with a different aim in life. For them, caterpillars are essential partners rather than prey. A caterpillar of the stonecrop blue butterfly feeds calmly on in the middle of a peaceful army of black ants. The ants tirelessly come and go. For them, the caterpillar is a living filling station. From a special gland in its abdomen, it produces a sweet liquid that the ants find irresistible. There are two sides to the bargain. In return for its contribution, the caterpillar enjoys the protection of a private army with a very real concern for its well-being. In early summer, the second phase of the caterpillar's life is coming to an end. They seem to be dying, but they're on the threshold of a great metamorphosis. These peacock caterpillars are about to pupate. Their entire way of life is now changing. Pupation is the end of their freedom. From now on, they will be able neither to move nor feed. They're prisoners in a rigid straitjacket. The chrysalis of a birdwing butterfly in Papua New Guinea wears a strangely human mask. It hangs suspended by a fine thread, a harness woven by the caterpillar before it pupated. The range of shapes and colors of moth and butterfly pupae is endless. And they are found everywhere, even underground. This deep vaulted burial chamber was built by a caterpillar of the sweet potato hawk moth. The chrysalis lies in state like a mummy under a pyramid. A few months later, the ground begins to move. The emerging moth struggles to push its way up into the light. In ancient times, it was believed to have risen from the tomb, having defeated death in line with the scriptures. Butterflies breaking free of the chrysalis were a symbol of immortality, an emblem of the eternal soul in an endless cycle of reincarnation. For some time after emerging, the adults are very vulnerable. The chitin that forms their outer skin hardens only slowly, and they have to pump up their wings. Water is more important for moths and butterflies than one might expect. Especially in the humid tropics, where it's always damp, water is the key to a highly specialized adaptation.
Everywhere is green and everywhere gleaming drops of water drip from leaves and stems. Among all these pearls, another one will hardly be noticed. It's the pupa of a monarch butterfly glinting like a large droplet, a perfect camouflage in a world of water. After the swift tropical twilight, new life awakens in a myriad hidden cocoons. The Indian luna moth is a creature of darkness and it emerges not into the light but into the night. Its enormous body is more than 2 in long, so it takes time to creep out of the restraining cocoon.
To begin with, its wings are tiny shriveled things but as blood and air are pumped into them, a small miracle takes place.
Finally, it spreads its hind wings which end in tails that can be 2 and 1/2 in long.
It takes more than half an hour before the process is complete.
But the night has many faces, especially in the tropics. In the virgin forests of Malaysia, strange creatures exist with weird outgrowths on their heads and huge nocturnal eyes. Their true nature emerges when they wake from their sleep and swarm out in search of food. The object of their search is the fruits of the forest. They drill deep into the pulp with their proboscis to suck out the juice, hence their name, fruit borers. They're exceptional among moths and butterflies in that they use force to get at their food. The length of the meal depends on the ripeness of the fruit and the sweetness of the juice. Different species specialize in drilling into different fruits. Some concentrate on citrus. Boring through the thick skin seems to present no problem for their sharp proboscis. In the depths of the Malaysian rain forest, the night hides a wide array of curious creatures, many of them little known. Some of them are dangerous even to human beings. Spending the night in the jungle is always risky with or without a fire. The light may repel some animals, but it will attract others. Another attraction is the characteristic scent of warm human skin.
One small inconspicuous moth responds to that scent like a fly to a honey pot. No matter what the species, human or non-human, it is powerfully attracted to warm-blooded animals.
When it lands, it waits motionless to see if its arrival has been detected.
If there's no response, it sets to work, very like its relations, the fruit borers.
But instead of fruit juice, it bores for blood. This moth is a true vampire. Pushing rhythmically into the wound, it can drill nearly half an inch in. The sleeper is undisturbed, but the moth stays alert. The loss of blood is insignificant, but bites like this can spread serious diseases. Even though the vampire is eventually sent on its way, it's still alive, taking a sample of this man's blood to inject into its next victim. Fortunately, vampire moths hunt alone and are quite scarce. In some parts of the world, butterflies gather in enormous numbers of the same species. They descend on the trees and rocks like an invading army. They are known as Russian bears because of their woolly caterpillars. Every midsummer on Rhodes, the Greek island of the gods, a becomes the center of attraction for millions of these butterflies about 2 in long. They gather in the cool, damp gorges cut by the streams. The clear water is inhabited by freshwater crabs. They are omnivorous and amphibian. They eat anything they can find and they often look for food on land. From time to time, a butterfly ventures too close to the water surface and falls in. Drifting helplessly, it's a gift to the waiting crab. There can be nowhere else on Earth where crabs actively hunt butterflies. Though it has to be said that the butterflies have something of an advantage being born to fly. On the magical island of Rhodes, the ancient interplay between hunter and hunted comes to a close with the setting of the sun. As they have for centuries, millions of butterflies rise as one into the evening air. The air is their element, perhaps prosaically merely to escape from their many enemies on the ground. But perhaps also, as the legend has it, they are wanderers through time and space on a mystical mission as the messengers of the gods.