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