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Nature's Most Destructive Swarm | 20 Years of Planet Earth | BBC Earth - Video học tiếng Anh

Nature's Most Destructive Swarm | 20 Years of Planet Earth | BBC Earth

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0:23There is no other species on the planet

0:25that responds as quickly and as

0:27dramatically to the good times. s as the

0:30desert locust.

0:32Eggs that have remained in the ground

0:34for 20 years begin to hatch.

0:49The young locusts are known as hoppers,

0:51for at this stage they're flightless.

0:54They find new feeding grounds by

0:57following the smell of sprouting grass.

1:06Normally it takes 4 weeks for hoppers to

1:09become adults, but when the conditions

1:11are right, as now, their development

1:13switches to the fast track.

1:21As the vegetation in one place begins to

1:23run out, the winged adults release

1:25phenommones, scent messages, which tell

1:28others in the group that they must move

1:30on.

1:42And when groups merge, they form a

1:45swarm.

2:08An adult locus eats its entire body

2:11weight every day, and a whole swarm can

2:13consume literally hundreds of tons of

2:16vegetation.

2:19They have to keep on moving.

2:22The swarm travels with the wind. It's

2:25the most energy saving way of flying.

2:31Following the flow of wind means that

2:34they're always heading toward areas of

2:36low pressure, places where wind meets

2:38rain and vegetation starts to grow.

2:44As they fly, swarms join up with other

2:47swarms to form gigantic plagues several

2:50billion strong and as much as 40 m wide.

2:56They will consume every edible thing

2:58that lies in their path.

3:13This is one of planet Earth's greatest

3:15spectacles.

3:17It's rarely seen on this scale, and it

3:19won't last long. Once the food has gone,

3:23the steady roar of a billion beating

3:25locust wings will once again be replaced

3:29by nothing more than the sound of the

3:31desert wind.