0:00:31 > 0:00:34A summer evening on the Koros river in central Europe.
0:00:34 > 0:00:36Its waters are mirror-smooth
0:00:36 > 0:00:41but, on this particular day of the year, all that is about to change.
0:00:43 > 0:00:47Giant mayflies, Europe's largest,
0:00:47 > 0:00:52are starting to rise to the surface and struggle out of the skins in which they lived as larvae.
0:00:59 > 0:01:01At first they come in ones and twos.
0:01:01 > 0:01:03Soon there will be millions.
0:01:10 > 0:01:13For two years, they have lived underwater.
0:01:13 > 0:01:16Now they must fly to find a mate.
0:01:16 > 0:01:19This should be the climax of their lives.
0:01:25 > 0:01:29The first to appear are quickly taken by predators.
0:01:35 > 0:01:41But soon the swarms are so huge that neither fish nor birds can make any impact on them.
0:01:41 > 0:01:49The first mayflies to emerge in this mass hatching on this river in Hungary are all males.
0:01:49 > 0:01:54As soon as they free themselves from their larval skins on the surface,
0:01:54 > 0:02:00they take off and seek safety in the banks and there they hang in trees and bushes,
0:02:00 > 0:02:04or indeed on my finger. The reason they have to rest like this
0:02:04 > 0:02:08is because they still have to make one final moult.
0:02:14 > 0:02:20Their wings that were transparent now have a handsome blue tinge
0:02:20 > 0:02:25and the elegant filaments at the end of their abdomens are even longer than before.
0:02:33 > 0:02:36They are looking for mates... but they have a problem.
0:02:36 > 0:02:40They can't feed for they have neither mouth nor stomach.
0:02:40 > 0:02:44They have to fuel their flight entirely from the reserves of fat
0:02:44 > 0:02:48that they built up when they were larvae feeding in the river.
0:02:48 > 0:02:55But that fat will only last them for about half an hour of flight time.
0:02:55 > 0:02:59So the race to mate now becomes a frantic one.
0:03:01 > 0:03:07The females begin to rise to the surface and the males fly up and down the river searching for them.
0:03:12 > 0:03:18As soon as they find one, they all pounce on her, competing to be the one to fertilise her eggs.
0:03:26 > 0:03:30But the struggle of doing so saps their limited energy.
0:03:32 > 0:03:36Before long they begin to run out of fuel
0:03:36 > 0:03:39and, though they flutter despairingly,
0:03:39 > 0:03:42they can't maintain themselves in the air.
0:03:49 > 0:03:52Win or lose, their lives are almost over
0:03:52 > 0:03:56and dead bodies start to litter the surface of the water.
0:03:59 > 0:04:02But the females are still in the air.
0:04:02 > 0:04:08They are flying upstream, judging the depth of the river
0:04:08 > 0:04:13and the currents in it, to find a place where they can lay their eggs
0:04:13 > 0:04:19so that they will float downriver to the same sort of place where the adults themselves lived as larvae.
0:04:22 > 0:04:26The ancestral mayflies were among the first creatures of any kind
0:04:26 > 0:04:30to take to the air about 320 million years ago.
0:04:30 > 0:04:33For them, as for their living descendants,
0:04:33 > 0:04:40flight was a brief but invaluable way of finding a mate and expanding their breeding territories.
0:04:40 > 0:04:47The river has also been the home of another kind of insect with an equally ancient ancestry
0:04:47 > 0:04:51and it too is beginning to emerge from the water.
0:04:51 > 0:04:59Bigger and more ferocious than the mayfly larvae, it has been feeding on tadpoles and even small fish.
0:04:59 > 0:05:02But that phase of its life is over.
0:05:02 > 0:05:08Now each one has to haul itself out of the water and into the air.
0:05:08 > 0:05:12On the top of its thorax, it carries a bulging back-pack.
0:05:24 > 0:05:28It hunches itself and its outer skin splits.
0:05:28 > 0:05:32A very different creature begins to appear.
0:05:32 > 0:05:35White threads are drawn out of its flanks.
0:05:35 > 0:05:41They are the linings of thin tubes that penetrate deep into its body -
0:05:41 > 0:05:45air tubes that enable the insect to breathe now that it is out of water.
0:05:57 > 0:05:59It gulps air...
0:05:59 > 0:06:04inflating its body, forcing fluid into the bundle on its back.
0:06:04 > 0:06:06Its wings begin to unfurl.
0:06:19 > 0:06:21Ten minutes later...
0:06:21 > 0:06:23the wings open.
0:06:23 > 0:06:25They will never close again.
0:06:29 > 0:06:36Next, the huge muscles within its thorax must be exercised to prepare them for action.
0:06:41 > 0:06:42And it's away.
0:06:50 > 0:06:57Dragonflies, like mayflies, belong to the most ancient group of insects that flew over the land
0:06:57 > 0:07:05and here in the museum in Harvard there are fossils of them that are 150 million years old.
0:07:08 > 0:07:13They are almost identical with species that are still flying today.
0:07:13 > 0:07:17However they are by no means the oldest.
0:07:18 > 0:07:23We know that there were other dragonflies even earlier,
0:07:23 > 0:07:25225 million years ago,
0:07:25 > 0:07:29that were flying through the swamps.
0:07:29 > 0:07:33We don't have complete specimens of any of those
0:07:33 > 0:07:37but there are some tantalising and amazing fragments.
0:07:37 > 0:07:39And here is one.
0:07:52 > 0:07:56This marvellously preserved wing
0:07:56 > 0:08:04has very much the same pattern of veins supporting panels of membranes as living species.
0:08:04 > 0:08:06The thing that makes it different
0:08:06 > 0:08:09is its size.
0:08:09 > 0:08:14From base to tip, it measures 12 inches, 30 centimetres.
0:08:14 > 0:08:20Little imagination is needed to replace the membrane that must have been there.
0:08:20 > 0:08:24This insect must have had a wing-span as big as a seagull's.
0:08:26 > 0:08:29Vibrating THESE wings
0:08:29 > 0:08:34preparing for flight must have been a formidable business.
0:08:43 > 0:08:50A creature this size must have been at least ten times heavier than the largest insect flying today.
0:08:50 > 0:08:52How did it manage to get into the air?
0:08:52 > 0:08:58One suggestion is that in those far-off times there was much more oxygen in the air
0:08:58 > 0:09:04and that would have given the extra power needed to beat these huge wings.
0:09:05 > 0:09:10But it is a fair guess that this ancient pioneer of the skies
0:09:10 > 0:09:15flew with much the same technique as dragonflies do today.
0:09:19 > 0:09:22Living dragonflies can reach speeds of nearly 40 miles an hour
0:09:22 > 0:09:26and fly several miles in their search for new territory.
0:09:37 > 0:09:43They are all aerial hunters, relying on their supreme aeronautical skills
0:09:43 > 0:09:45to snatch their prey from the sky.
0:09:51 > 0:09:56Their great agility in the air comes from being able to beat
0:09:56 > 0:10:00each of their two pairs of wings quite independently.
0:10:04 > 0:10:09You can see clearly that they do this...
0:10:09 > 0:10:12when the camera slows down the action 400 times.
0:10:12 > 0:10:16This one is coming in to its perch.
0:10:16 > 0:10:20Perfect control is essential to make all the tiny adjustments needed
0:10:20 > 0:10:23for an accurate pinpoint touchdown.
0:10:35 > 0:10:40All dragonflies, when they perch, hold their wings outstretched.
0:10:40 > 0:10:44But they have close relations, damselflies,
0:10:44 > 0:10:47and they perch with their wings closed above their backs.
0:10:47 > 0:10:51Mosquitoes stand little chance when damsels go hunting.
0:11:01 > 0:11:04But flight for damsels, as for dragonflies and mayflies,
0:11:04 > 0:11:07is primarily the means to find a mate and to breed
0:11:07 > 0:11:12and to do that they, like the others, need water.
0:11:15 > 0:11:19Flight is itself an important element in their courtship.
0:11:19 > 0:11:25These blue males must first establish a territory for themselves above open water
0:11:25 > 0:11:30and that involves aerial jousts that can last for hours.
0:11:35 > 0:11:37Mature females,
0:11:37 > 0:11:40whose wings in this species are not blue but golden brown,
0:11:40 > 0:11:45are attracted to those males who control good places for egg-laying.
0:11:45 > 0:11:50But the males must nonetheless display the correct wing signals.
0:11:51 > 0:11:56This one, patrolling his territory, is using a special flight,
0:11:56 > 0:12:00flaunting his handsome wings, inviting females to join him.
0:12:05 > 0:12:11A female signals her willingness to consider doing so with a flick of her wings.
0:12:18 > 0:12:21So now he treats her to his full display.
0:12:28 > 0:12:33The female's tail-up posture is apparently a signal
0:12:33 > 0:12:36that declares that she is not yet sufficiently impressed.
0:12:42 > 0:12:45Now, it seems, he's got it right -
0:12:45 > 0:12:48her tail is pointing downwards.
0:12:48 > 0:12:54He grabs the back of her neck with the claspers at the end of his abdomen.
0:12:55 > 0:13:02She brings her abdomen forward to reach a chamber under his thorax where he stores his sperm.
0:13:02 > 0:13:06His first action, though, is to scour out her genital tract
0:13:06 > 0:13:10to remove any sperm that might be there from a previous mating.
0:13:10 > 0:13:13Only when he's done that will he inject his own sperm.
0:13:19 > 0:13:24And now he must show her the best places in his territory for laying eggs.
0:13:30 > 0:13:35He flies up and down, with his tail curled, and lands on a suitable piece of vegetation.
0:13:40 > 0:13:45The female settles down to lay, cutting slits in the plant stems
0:13:45 > 0:13:49with her ovipositor and inserting an egg into each one.
0:13:49 > 0:13:52She may lay as many as 30.
0:13:54 > 0:14:01And all the time, the male keeps guard lest rival males should try to mate with her.
0:14:04 > 0:14:07In other damsel species, the males make sure
0:14:07 > 0:14:13that no other male can reach their partners by keeping hold of them throughout the whole process.
0:14:22 > 0:14:26The young that hatch from the eggs of these insects, the larvae,
0:14:26 > 0:14:28look very unlike their parents.
0:14:28 > 0:14:30This is a dragonfly larva.
0:14:30 > 0:14:34It is in this form that dragonflies spend most of their lives.
0:14:34 > 0:14:39The larvae of both dragonfly and damselfly are savage predators.
0:14:39 > 0:14:43They will even feed on their own kind if they get the chance.
0:14:52 > 0:14:58This particular larva has a special problem. It's a cascade damsel
0:14:58 > 0:15:03and it has to snatch prey that is swept past it by the rushing water.
0:15:05 > 0:15:10Cascade damsels are very rare and live around just a few Central American waterfalls,
0:15:10 > 0:15:14like this one in the mountains of Costa Rica.
0:15:23 > 0:15:31The adult male has to perform his courtship flight under very difficult conditions indeed.
0:15:47 > 0:15:53Somehow, he is able to fly even when he is dripping wet and he shows off to the females
0:15:53 > 0:15:57by actually flying through the cascades of water.
0:16:02 > 0:16:06To be a good breeding territory, the vertical rock surface has to be covered
0:16:06 > 0:16:09by just the right amount of water.
0:16:09 > 0:16:11Too deep, and prey may be out of reach,
0:16:11 > 0:16:16too shallow and the larvae could be picked off by birds.
0:16:17 > 0:16:23A female will only mate with a male if she approves of his choice of territory.
0:16:23 > 0:16:26And this one, it seems, does.
0:16:40 > 0:16:44This is it, and she carefully fixes her eggs to the rocks.
0:16:56 > 0:17:01But not all damsels need great areas of open water for breeding.
0:17:04 > 0:17:06In the rainforest of Central America,
0:17:06 > 0:17:10like this one here in Costa Rica, there is a damselfly
0:17:10 > 0:17:15that has managed to break the link with open expanses of water like rivers and ponds.
0:17:15 > 0:17:20It's also one of the most spectacular members of the entire family.
0:17:24 > 0:17:31The helicopter damselfly, the largest in the world with a wing-span of up to 20 centimetres.
0:17:33 > 0:17:39The males tend to frequent sunlit patches where the females can see them easily
0:17:39 > 0:17:45and they have a special lazy flapping way of flying that is, in itself, an invitation.
0:17:58 > 0:18:04But although helicopter damsels can live away from rivers and streams,
0:18:04 > 0:18:10the females nonetheless require a little water in which to lay their eggs...
0:18:10 > 0:18:13and there is just enough
0:18:13 > 0:18:15in this little hollow here.
0:18:15 > 0:18:17And with luck she will come down.
0:18:34 > 0:18:36And into the water they go.
0:18:45 > 0:18:51But these eggs have water-tight casings, so they can be laid in air.
0:18:51 > 0:18:55They're butterfly eggs. The link with water has been broken.
0:18:58 > 0:19:03Butterflies fly in a very different way from dragonflies.
0:19:03 > 0:19:08They overlap their two pairs of wings so that they flap as a single pair.
0:19:08 > 0:19:12They can't fly as fast or as aerobatically as dragonflies
0:19:12 > 0:19:17but they nonetheless are tireless in their search for the particular food that will suit their young.
0:19:17 > 0:19:22And, in the case of the cabbage white, that's cabbage.
0:19:30 > 0:19:33Now on the surface of this cabbage leaf
0:19:33 > 0:19:37there is a patch of tiny little pillbox shaped eggs.
0:19:37 > 0:19:44And when they hatch, the baby caterpillars will emerge and make an instant meal of the greenery.
0:19:47 > 0:19:50And they are already stirring.
0:19:55 > 0:20:00But the first dish on the menu is not vegetables.
0:20:00 > 0:20:03It's the shells of their own egg capsules,
0:20:03 > 0:20:06protein rich and far too nourishing to be wasted.
0:20:06 > 0:20:11That first course, however, doesn't last long.
0:20:11 > 0:20:15Now for the main dish - cabbage leaves.
0:20:16 > 0:20:20When cabbage plants are damaged, their leaves release a smell
0:20:20 > 0:20:25and that quite often attracts the attention of a rather different insect.
0:20:31 > 0:20:35It's a tiny wasp called cotesia.
0:20:35 > 0:20:39She too is trying to make sure that her young have food immediately available,
0:20:39 > 0:20:42but they like living flesh.
0:20:42 > 0:20:46So she injects her eggs into the butterfly's caterpillars.
0:20:51 > 0:20:58She does this with such surgical precision that her victims are not mortally injured
0:20:58 > 0:21:01and they continue feeding as if nothing had happened to them.
0:21:12 > 0:21:18But now much of what the caterpillars so laboriously gather
0:21:18 > 0:21:22goes to nourish the wasp grubs that are developing within them.
0:21:24 > 0:21:27As the caterpillars grow, they shed their skins.
0:21:27 > 0:21:31They do so five times until, ultimately,
0:21:31 > 0:21:36they are 800 times heavier than they were when they first hatched.
0:21:36 > 0:21:40This fully-grown caterpillar must now find shelter.
0:21:44 > 0:21:47A strand of silk trails behind it,
0:21:47 > 0:21:50silk with which it ties itself to a twig.
0:21:50 > 0:21:54And here, over a couple of days, it changes into a chrysalis.
0:22:03 > 0:22:09Those caterpillars that were injected by the cotesia wasp don't get that chance.
0:22:09 > 0:22:13The grubs within them are now emerging.
0:22:21 > 0:22:28They too spin silk which hardens to form a cocoon beneath the caterpillar's empty skin.
0:22:33 > 0:22:36Inside, the wasp grubs are transforming themselves
0:22:36 > 0:22:40and two weeks later, out come the adult wasps.
0:23:00 > 0:23:04A different future awaits the chrysalis.
0:23:04 > 0:23:07Within its shell and over a similar two weeks,
0:23:07 > 0:23:10the caterpillar's body has been broken down and reassembled
0:23:10 > 0:23:13and now the adult is ready to emerge.
0:23:18 > 0:23:24Its wings, like those of a newly-emerged dragonfly, need pumping up with liquid.
0:23:36 > 0:23:43The creature that was once an egg, then a caterpillar, then a chrysalis has attained its final incarnation.
0:23:48 > 0:23:54So another generation of cabbage whites set off to find good places for their young.
0:23:55 > 0:24:00With their fragile-looking wings and apparently erratic flight,
0:24:00 > 0:24:04butterflies might not seem to be the most powerful of flyers,
0:24:04 > 0:24:08but in fact they are extremely accomplished aeronauts
0:24:08 > 0:24:14and they can fly hundreds of miles if necessary to find the food they need.
0:24:22 > 0:24:26Some butterflies use the power of flight for another purpose -
0:24:26 > 0:24:29to escape bad weather.
0:24:29 > 0:24:32These lush sub-tropical valleys in southern Taiwan
0:24:32 > 0:24:40are warm and green all year round and in winter, they are filled by literally millions of butterflies.
0:24:51 > 0:24:57They have all come from the north of this great island, 500 miles away, for there the cold weather
0:24:57 > 0:25:02has killed off the plants on which they fed during the summer.
0:25:08 > 0:25:11In the mornings they take off from their roosts
0:25:11 > 0:25:17and head for the forest canopy, to warm themselves in the rays of the rising sun.
0:25:17 > 0:25:21They have to conserve as much energy as they can,
0:25:21 > 0:25:26so instead of using their stores of fat to warm themselves, they absorb the sun's heat.
0:25:34 > 0:25:39There are four species of crow butterflies here as well as two species of blue tiger butterflies...
0:25:39 > 0:25:45and all find enough food to sustain themselves in these warm and fertile valleys.
0:25:47 > 0:25:51Butterflies feed on liquid, nectar and the juices of rotting fruit
0:25:51 > 0:25:56and to suck it up they have, instead of jaws,
0:25:56 > 0:26:00an extraordinarily long but extremely thin tube.
0:26:07 > 0:26:12In a newly-emerged butterfly this tube is in two pieces,
0:26:12 > 0:26:16for it is in fact a highly modified pair of mouthparts.
0:26:16 > 0:26:23Each half has its own muscles and nerve supply so that the whole unit is fully movable and controllable.
0:26:27 > 0:26:31As the young butterfly prepares for adult life, these two sections
0:26:31 > 0:26:35are zipped together to form a tube like a miniature drinking straw.
0:26:35 > 0:26:39A special fluid cements the two halves together.
0:26:39 > 0:26:44The tube is largely made of a material called resilin which,
0:26:44 > 0:26:47when distorted, springs back to its original shape,
0:26:47 > 0:26:50in this case a spiral like a watch spring.
0:26:50 > 0:26:54When the muscles within it contract, it straightens into a long probe
0:26:54 > 0:26:58that the butterfly can then insert deep into a flower.
0:27:12 > 0:27:17Butterflies and moths have the largest of all insect wings
0:27:17 > 0:27:20and their great size means that they can be used very effectively
0:27:20 > 0:27:27as billboards on which to display patterns proclaiming the species of their owner.
0:27:27 > 0:27:32The patterns are produced by tiny scales that cover the wings like tiles on a roof.
0:27:32 > 0:27:34Some have a microscopic structure
0:27:34 > 0:27:39that refracts the light and gives the wing a brilliant iridescent shimmer.
0:27:39 > 0:27:42Others contain chemical pigments.
0:27:47 > 0:27:54With these lovely advertisements, a male butterfly displays to females and warns off rivals.
0:27:58 > 0:28:04Vivid patterns and bright colours are used to a much lesser degree by moths,
0:28:04 > 0:28:08for many are only active at night when colours are not easily seen.
0:28:12 > 0:28:19Moths also feed primarily on nectar which they suck up in the same way that butterflies do.
0:28:19 > 0:28:25But one moth manages to tap a food source no butterfly has yet exploited.
0:28:27 > 0:28:35Lantern bugs feed by drilling into the bark of a tree with their proboscis and sucking out the sap.
0:28:35 > 0:28:39This contains a little protein, which the bug wants,
0:28:39 > 0:28:42but a lot of sugar, most of which it doesn't want.
0:28:42 > 0:28:48So it squirts out the sweet excess and to make sure that this doesn't attract ants that might attack it,
0:28:48 > 0:28:51it fires the droplets well away from the tree trunk
0:28:51 > 0:28:56with a tiny spring-loaded spatula at the end of its abdomen.
0:29:04 > 0:29:10One enterprising species of moth regularly sits behind the bug all night
0:29:10 > 0:29:16with the curled tip of its proboscis delicately placed in the stream of droplets.
0:29:28 > 0:29:33As sugar water accumulates, so the moth sucks it up.
0:29:41 > 0:29:48Most moths, however, feed by the rather more laborious method of flying from flower to flower.
0:29:48 > 0:29:50A few, the busiest,
0:29:50 > 0:29:53do so not only at night but during the day as well.
0:29:53 > 0:29:56These are the hawk moths and there are several species of them
0:29:56 > 0:30:00gathering nectar from this buddleia bush in the south of France.
0:30:03 > 0:30:07This hawk moth can fly very fast indeed when it wants to
0:30:07 > 0:30:13but it can also hover, as it's doing now, to sip nectar
0:30:13 > 0:30:18from each of these small flowers. Beating its wings as fast as this,
0:30:18 > 0:30:22takes a great deal of energy
0:30:22 > 0:30:26so these hawk moths have to spend much of their day
0:30:26 > 0:30:29going from flower to flower sipping the nectar
0:30:29 > 0:30:33which is so rich in the carbohydrates they need to power their flight.
0:30:38 > 0:30:44They have huge forward-pointing eyes that enable them to aim their proboscis with such accuracy
0:30:44 > 0:30:48that it slips into the exact centre of each tiny flower.
0:30:50 > 0:30:53With so many minute flowers so closely bunched together,
0:30:53 > 0:30:57it would be easy for the moth to visit some twice.
0:30:57 > 0:31:01But that would waste energy and if we mark each flower as the moth drinks from it,
0:31:01 > 0:31:05it's clear that the moth, somehow or other, never does this.
0:31:12 > 0:31:17Hummingbird hawk moths have no difficulty in hovering.
0:31:17 > 0:31:20Bee hawks however, have heavier bodies
0:31:20 > 0:31:25and they sometimes use their legs to help support themselves as they work.
0:31:30 > 0:31:36Their need to keep drinking is so pressing that a female will continue to do that
0:31:36 > 0:31:42even when the male with whom she is mating seems to be trying to fly in the opposite direction.
0:31:44 > 0:31:49The buddleia plant may be a particular favourite of hawk moths
0:31:49 > 0:31:55but it is, of course, a foreigner, introduced into our gardens from China in the 19th century.
0:31:55 > 0:32:00The hawk moth's original supplies of nectar came from the flowers of the meadows.
0:32:00 > 0:32:04And they still feed there, alongside many other insects.
0:32:04 > 0:32:07This is a carpenter bee.
0:32:07 > 0:32:11Bees also have two pairs of wings but they are hooked together
0:32:11 > 0:32:15so, like those of butterflies, they operate as one.
0:32:17 > 0:32:25Bumblebees have particularly large and heavy bodies and flight, for them, can be a real effort.
0:32:25 > 0:32:29That is particularly so in spring when the mornings are cold
0:32:29 > 0:32:33and queen bumblebees are just emerging from their winter sleep.
0:32:33 > 0:32:40It is still only a few degrees above freezing, but a queen needs to get started early to look for food.
0:32:40 > 0:32:46The thick furry hairs on her body help to conserve what heat she manages to generate.
0:32:48 > 0:32:52At the moment she is only a few degrees warmer than the surrounding vegetation,
0:32:52 > 0:32:55as a thermal camera clearly shows.
0:32:55 > 0:33:00Her body is only marginally more pink than the blue leaves and moss around her.
0:33:02 > 0:33:05But she has a special way of warming up for flight.
0:33:08 > 0:33:12She can put her wings out of gear so that, without moving them,
0:33:12 > 0:33:15she can rev up the wing muscles inside
0:33:15 > 0:33:18and that raises the temperature within her thorax
0:33:18 > 0:33:20by 20 degrees centigrade or more
0:33:20 > 0:33:24as the expanding yellow image on the thermal camera indicates.
0:33:34 > 0:33:39Her body temperature is now over 30 degrees centigrade.
0:33:39 > 0:33:41At last, she has a chance of lift-off.
0:33:54 > 0:34:01She will now be able to visit the spring flowers while it is still too cold for others to do so.
0:34:17 > 0:34:22The long trumpets of the daffodils retain heat very well and they are still warm
0:34:22 > 0:34:25even after their hot-bodied visitors have left.
0:34:32 > 0:34:35Flies, back in their distant evolutionary past,
0:34:35 > 0:34:40also had two pairs of wings, but their back pair have been reduced
0:34:40 > 0:34:43to simple knob-ended rods.
0:34:44 > 0:34:47These are particularly long on crane flies.
0:34:47 > 0:34:51They are part of a fly's flight instrumentation.
0:34:51 > 0:34:55Microscopic sensors on their upper and lower surfaces tell their owner
0:34:55 > 0:34:59about the air currents around its body and so help in flight control.
0:34:59 > 0:35:02They start up even before take-off.
0:35:08 > 0:35:14Flies are such accomplished flyers that they can land upside-down on a ceiling
0:35:14 > 0:35:18or, in this case, the underside of a twig.
0:35:28 > 0:35:32Only when you slow down a fly's flight, here by 100 times,
0:35:32 > 0:35:36can you fully appreciate what superb aerial control they have.
0:35:44 > 0:35:52Some species, like these long-legged flies, flaunt their wings in courtship, just as damselflies do.
0:36:01 > 0:36:03These dance flies are voracious hunters
0:36:03 > 0:36:09and it is particularly important for them that they perform their dance correctly.
0:36:09 > 0:36:13If one doesn't get it right, its partner might well eat it.
0:36:40 > 0:36:43This performance, however, seems to have been up to standard.
0:37:09 > 0:37:11For hoverflies,
0:37:11 > 0:37:14arguably the most accomplished of all insect aviators,
0:37:14 > 0:37:19immaculate aerial control is what makes a male attractive to a female.
0:37:21 > 0:37:25A male lays claim to a mating territory by trying to stay
0:37:25 > 0:37:29in exactly the same position in space for as long as possible.
0:37:29 > 0:37:37That is not easy when there are others all around you, trying to do precisely the same thing.
0:37:37 > 0:37:41It might seem that he is absolutely motionless,
0:37:41 > 0:37:47but in fact he is having to make continual changes to adjust for slight currents in the air.
0:37:47 > 0:37:51It is an amazing piece of acrobatics,
0:37:51 > 0:37:56far better than anything that we can do in a helicopter.
0:37:56 > 0:38:00And it is all done in order to impress the female,
0:38:00 > 0:38:06to show her that he is superb at holding his territory.
0:38:08 > 0:38:15Having to chase away rivals that come too close is an exhausting business
0:38:15 > 0:38:20and when you are trying to maintain your hold on a particular point in mid-air,
0:38:20 > 0:38:24even a small midge has to be chased away.
0:38:31 > 0:38:38After a morning spent doing this, a male hoverfly may have lost as much as a third of his body weight.
0:38:38 > 0:38:43Little wonder that he takes a break at mid-day in order to rest and refuel.
0:38:43 > 0:38:47He dabs up nectar with mouth-parts that are shaped like a pad.
0:38:58 > 0:39:05Having refilled his fuel tank, the male returns to his territory for the afternoon's session of hovering,
0:39:05 > 0:39:08in the hope of attracting yet another female and mating with her.
0:39:13 > 0:39:17Once again, with his superb eyesight,
0:39:17 > 0:39:23he is ready to spot anything that might whiz by him at high speed that could be a female.
0:39:23 > 0:39:27And I might just be able to fool him with a pea-shooter.
0:40:07 > 0:40:13Although there may seem to be an extraordinarily large number of different flies in the world,
0:40:13 > 0:40:17it is actually the beetles that are the most varied of all insect groups.
0:40:17 > 0:40:21There are 300,000 species of them.
0:40:21 > 0:40:26Most find their food by crawling and burrowing on the ground and to prevent their wings
0:40:26 > 0:40:32from being damaged in the process, they have turned the front pair into protective shields.
0:40:32 > 0:40:38Some, like weevils, keep their wing-covers permanently closed and before take-off
0:40:38 > 0:40:42push their functional wings out of special slits.
0:40:43 > 0:40:47Ladybirds, like most other beetles, raise their wing covers
0:40:47 > 0:40:50and hold them clear of the hind wings throughout their flight.
0:40:50 > 0:40:56The result could hardly be called aerodynamic and consequently their flight is rather lumbering.
0:41:01 > 0:41:04Blister beetles are scarcely any better.
0:41:10 > 0:41:15When a flight is over, the hind wings have to be packed away beneath the covers -
0:41:15 > 0:41:21a process that can be so complex that it demands all the skills of a Japanese master of origami.
0:41:38 > 0:41:45With flight playing a relatively small part in their lives, many beetles have grown very large.
0:41:45 > 0:41:48This one, the titan beetle that lives in the forests of the Amazon,
0:41:48 > 0:41:52is almost certainly the biggest of all insects.
0:41:55 > 0:41:59I have to handle him with considerable care
0:41:59 > 0:42:04because these huge mandibles at the front are powerful enough, it's said,
0:42:04 > 0:42:09to be able to cut straight through a pencil.
0:42:09 > 0:42:12He can fly, but he can't get into the air from the ground.
0:42:12 > 0:42:18He's too heavy to do that, so he has to climb trees and launch himself into the air that way.
0:42:18 > 0:42:23That is why he has got such powerful legs, armed with sharp claws.
0:42:23 > 0:42:28The titan is now known to be the biggest of all beetles.
0:42:28 > 0:42:35The champion is seven inches long from the tip of its mandibles to the tip of its abdomen.
0:42:35 > 0:42:40The larva of this great monster has not yet been found
0:42:40 > 0:42:46but it must be at least twice as big as the beetle, a really huge grub.
0:42:46 > 0:42:50Beetles and many other insects spend so much of their lives as flightless larvae
0:42:50 > 0:42:56that it would be more accurate to think of them as creatures of the earth rather than the sky.
0:42:56 > 0:42:58Flight for them, as it is for the mayflies,
0:42:58 > 0:43:03is a relatively brief episode at the end of their lives.
0:43:03 > 0:43:08These cicadas in the eastern United States, spend 17 whole years below ground,
0:43:08 > 0:43:11sucking sap from tree roots.
0:43:11 > 0:43:15And then, within a few days, a whole population emerges.
0:43:30 > 0:43:34There may be millions of them in a single acre of land.
0:43:43 > 0:43:50They clamber up the trees whose roots have provided them with sap for all of those 17 years.
0:44:06 > 0:44:10And here they change into their adult costume.
0:44:34 > 0:44:39Now they have the wings they need to search for a partner.
0:44:43 > 0:44:47Empty larval cases cover the tree trunks and the ground beneath.
0:44:52 > 0:44:57And above, in the branches, the millions have started to sing.
0:44:57 > 0:44:59The noise is ear-splitting.
0:44:59 > 0:45:03HIGH-PITCHED SCREECHING
0:45:15 > 0:45:18After 17 years of living underground,
0:45:18 > 0:45:23the cicadas are now approaching the climax of their lives.
0:45:23 > 0:45:27And for the males, that means this.
0:45:32 > 0:45:36The call is his way of attracting a female.
0:45:44 > 0:45:48The females reply with a quite different sound.
0:45:50 > 0:45:55A click made by flicking her wings.
0:45:55 > 0:45:58That's what the males are listening out for.
0:45:58 > 0:46:04I can imitate the female's wing flick with a snap of my fingers...
0:46:04 > 0:46:07and that causes them to follow me anywhere,
0:46:07 > 0:46:11because they are so determined to find a female.
0:46:26 > 0:46:28Now I can bring you back?
0:46:32 > 0:46:35How about coming this way?
0:46:43 > 0:46:46Oh! The noise is awful.
0:46:46 > 0:46:49Come this way.
0:46:49 > 0:46:52Yes, I can hear you.
0:46:55 > 0:46:56Quite right.
0:46:58 > 0:47:01At last, a male finds his partner
0:47:01 > 0:47:04and as he does so, his call alters.
0:47:06 > 0:47:11He is indicating to her that, after 17 years,
0:47:11 > 0:47:15the time has come to get down to business.
0:47:30 > 0:47:37How do these cicadas all emerge simultaneously after 17 long years?
0:47:37 > 0:47:43Well, we know they can appreciate changes in the content of tree sap,
0:47:43 > 0:47:46so they are able to detect the passing of a year.
0:47:46 > 0:47:49But how do they count up to 17?
0:47:49 > 0:47:51We have no idea.
0:47:51 > 0:47:55But even if we did, this surely would remain
0:47:55 > 0:47:59one of the most astonishing, amazing events in the insect world
0:47:59 > 0:48:06and it will all be over in a couple of weeks for another 17 years.
0:48:27 > 0:48:30In the next programme of Life In The Undergrowth,
0:48:30 > 0:48:38we tell the story of a substance that completely revolutionised the lives of invertebrates - silk.
0:48:42 > 0:48:46Many different creatures use this wonderful material,
0:48:46 > 0:48:51but you can't tell the story of silk without the silk masters - spiders.
0:48:54 > 0:48:59And for some people that's a bit of a problem.
0:48:59 > 0:49:04A lot of us find spiders really rather upsetting.
0:49:04 > 0:49:06Why that should be is not clear to me.
0:49:06 > 0:49:10Perhaps it's because they've got eight legs
0:49:10 > 0:49:14and move in a most unpredictable way, and what's more move very fast.
0:49:14 > 0:49:19But whatever the reason is, a lot of people do hate spiders.
0:49:19 > 0:49:23But if you can once overcome that dislike
0:49:23 > 0:49:28then you look at the animal as an animal with problems to solve -
0:49:28 > 0:49:31how to find its mate, how to find food,
0:49:31 > 0:49:34how it constructs these elaborate webs,
0:49:34 > 0:49:40which must be among the most extraordinary constructions in the whole of the animal world.
0:49:40 > 0:49:44Once you can do that, you see how absolutely astonishing they are.
0:49:44 > 0:49:48And that was the key challenge for the next episode -
0:49:48 > 0:49:56to see beyond our fear and uncover the fascinating way in which spiders use silk.
0:49:56 > 0:50:02And where better to start than with the Australian redback.
0:50:02 > 0:50:05This is one of the world's most notorious spider.
0:50:05 > 0:50:09Do you get many redback bites?
0:50:09 > 0:50:15- Somewhere between 500 and 1,000 bites every year.- But you don't die from it?- Well, people have died,
0:50:15 > 0:50:22- but this is a slow-acting venom. It might take five days for someone to die from it.- So you've got time?
0:50:22 > 0:50:28'Warwick Angus is an expert on redback webs, and he's convinced
0:50:28 > 0:50:33'that if you treat these spiders with respect there's no need to fear them.'
0:50:33 > 0:50:39They're not aggressive, they're the opposite, they're defensive. But they're so placid.
0:50:39 > 0:50:43There she is, showing no signs of aggression. But that's her home,
0:50:43 > 0:50:50and if we pick up the plant pot, we're destroying her home and she can't talk...she can only bite!
0:50:50 > 0:50:52Encouraged by Warrick,
0:50:52 > 0:50:56I can put my caution aside and focus on the complex web
0:50:56 > 0:51:00she has built under the plant pot, which we were there to film.
0:51:00 > 0:51:06You might think it's just a cobweb, but in fact it's a very subtle construction. There is a dome...
0:51:06 > 0:51:13over the top part and, from the dome, there are a lot of vertical threads which go down to the ground.
0:51:13 > 0:51:17An ant crawling along the bottom of this decking,
0:51:17 > 0:51:23if it touches one of these vertical strands, the strand breaks
0:51:23 > 0:51:27and whips up the ant and then the spider can catch it.
0:51:27 > 0:51:33When you can see all this, you gain a whole new appreciation for this creature.
0:51:33 > 0:51:36And there's an encouraging twist to Warrick's story.
0:51:36 > 0:51:39What made you first get involved in spiders?
0:51:39 > 0:51:41I mean, spiders are your life now.
0:51:41 > 0:51:47- I used to be arachnophobic.- Really? You mean you actually hated spiders?
0:51:47 > 0:51:53I couldn't go in the room if there was a spider. I had to run outside, I couldn't handle it.
0:51:53 > 0:51:57But once I started to try and get over the fear,
0:51:57 > 0:52:02that fear led to a fascination, that fascination just grew and grew.
0:52:02 > 0:52:06From arachnophobe to expert. There's hope for us all.
0:52:08 > 0:52:11And it doesn't end there.
0:52:11 > 0:52:17In Malaysia, cameraman Gavin Thurston is looking for another spider which we wanted to film -
0:52:17 > 0:52:19the trapdoor spider.
0:52:20 > 0:52:25He's had a similar discovery about the expert he's working with - Stephen Hogg.
0:52:25 > 0:52:29Just an interesting point Stephen was just telling me.
0:52:29 > 0:52:34Stephen's our spider expert, but he's actually afraid of spiders!
0:52:34 > 0:52:38Well, since childhood I'm terrified of them!
0:52:38 > 0:52:41It makes my heart beat, they terrify me.
0:52:41 > 0:52:48And just like Warrick and his Redbacks, Stephen's fear of spiders has somehow led to a fascination.
0:52:48 > 0:52:51..Will walk along the lines of silk.
0:52:51 > 0:52:55The spider detects this and lunges out and grabs its prey.
0:52:57 > 0:53:03That night, Stephen and Gavin return to film this nocturnal spider in its burrow
0:53:03 > 0:53:05with the help of a chip on the tip camera -
0:53:05 > 0:53:10a remote controlled probe with a tiny camera and light on the end.
0:53:12 > 0:53:19As Gavin carefully feeds the probe into the spider's burrow, Stephen can watch from a distance.
0:53:19 > 0:53:22Unlike Warwick he hasn't quite got over his arachnophobia.
0:53:22 > 0:53:25That's it...hold it. That's good.
0:53:25 > 0:53:32Though that's hardly surprising when you get a close look at this spider - hairy legs, huge fangs.
0:53:34 > 0:53:38But with this probe, he can see beyond all that.
0:53:40 > 0:53:46And for the very first time, we can film the detail of this spider's remarkable trap.
0:53:48 > 0:53:53An ingenious silk collar connected to the external tripwires keep the spider's feet
0:53:53 > 0:53:58constantly in touch with the outside world, ready to pounce.
0:54:03 > 0:54:08Another night, another spider. This time, not quite so scary -
0:54:08 > 0:54:10the bolas spider.
0:54:12 > 0:54:14It's also nocturnal...
0:54:14 > 0:54:17and is very sensitive to light.
0:54:17 > 0:54:20So we have to approach it very carefully under red light at first.
0:54:20 > 0:54:24Then when it is comfortable with our cameras, we wait...
0:54:28 > 0:54:29Here's its prey.
0:54:31 > 0:54:35Once it's locked onto the moth, it won't mind the light.
0:54:49 > 0:54:51Its weapon -
0:54:51 > 0:54:55a single strand of silk with a drop of glue on the end.
0:54:57 > 0:55:02The more we look at spiders, the more fascinating they become.
0:55:02 > 0:55:06You can't help your jaw sagging just a little and saying,
0:55:06 > 0:55:11my goodness how absolutely extraordinary that they can behave
0:55:11 > 0:55:14in this complicated and seemingly intelligent way,
0:55:14 > 0:55:20when they are the size they are with the number of brain cells they must have tucked away
0:55:20 > 0:55:28in a little tiny invisible point in the middle of that head.
0:55:28 > 0:55:30Amazing.
0:55:34 > 0:55:42But to really understand spiders, you have to completely immerse yourself in their world.
0:55:43 > 0:55:49Tim Shepherd spent a total of 200 hours filming a spider that you can commonly find in your garden -
0:55:49 > 0:55:51a wolf spider.
0:55:51 > 0:55:57They really are little. Their leg span is probably the width of your little finger nail.
0:55:57 > 0:56:01When you start to see them under really big macro lenses,
0:56:01 > 0:56:05you go into a completely different world
0:56:05 > 0:56:07and you start to, after a while,
0:56:07 > 0:56:11begin to get a feel of what it might be like to be a spider
0:56:11 > 0:56:15and to walk past a piece of moss that's actually like a tree trunk.
0:56:17 > 0:56:22It's nearly impossible to film a spider this small in the wild
0:56:22 > 0:56:24but, because it's so tiny,
0:56:24 > 0:56:28Tim can easily create a complete habitat for it in a studio
0:56:28 > 0:56:31in which it will be quite at home.
0:56:31 > 0:56:35Filming these wolf spiders has revealed
0:56:35 > 0:56:38a whole array of behaviour
0:56:38 > 0:56:42from the superb little courtship behaviours that the males do,
0:56:42 > 0:56:47through to the female making this incredible little egg pouch -
0:56:47 > 0:56:51it's a structure that's intricate and beautiful -
0:56:51 > 0:56:56and then she carries it around and looks after the babies when they hatch.
0:56:56 > 0:57:01So she's got this wonderful maternal care to her character.
0:57:01 > 0:57:07So all these different things help to make spiders much more interesting
0:57:07 > 0:57:10than a big scary creature that's about to bite you.
0:57:10 > 0:57:15But that's not to say that some spiders aren't big and scary.
0:57:15 > 0:57:19In Australia, Warrick is proof that no-one's immune from arachnophobia,
0:57:19 > 0:57:24and he's determined to convince everyone that it's something well worth getting over,
0:57:24 > 0:57:30with Incy Wincy, his big, hairy and venomous bird eating spider.
0:57:30 > 0:57:33Go on, David, have a cuddle.
0:57:33 > 0:57:35- Oh... - OTHERS LAUGH
0:57:36 > 0:57:41If there are many reasons to dislike spiders,
0:57:41 > 0:57:45then Incy Wincy encapsulates all of them.
0:57:47 > 0:57:53However, knowing that she was no threat to me as long as I was no threat to her, reassured me.
0:57:53 > 0:57:54We had an understanding.
0:57:54 > 0:57:57Just two creatures trying to solve life's problems.
0:58:33 > 0:58:36Subtitles by Red Bee Media Ltd