'Why? You're not frightened of it, are you?It's only an insect.'
'It isn't an insect,Debbie,though it might look like one.
Actually, it's a very useful creature.
The programme I watched last night has completely changed my views on spiders.
Do you want to hear about it?'
'Not really,' sighed Debbie'but I suppose you're going to tell me anyway.'
'Spiders,' said Simon,ignoring her remarks,
'are the enemies of insects and the friends of humans.
That's something that Chinese farmers realized years ago
and scientists are only beginning to understand today.
'Do you know that in parts of China,in the autumn,
farmers build shelters for spiders and put them all over their fields?
They're like little cone-shaped tents made of straw
and the spiders can survive the winter in them.
When spring comes, the spiders emerge healthy and hungry,
at the same time as millions of insects arrive to attack the farmers' crops.'
So the spiders fill their empty stomachs,
and the fanners whose fields are protected are happy.
They've saved their crops and their money.
Because of the spiders their expenditure on insecticides is nil.'
'So everyone's happy except the insects,' said Debbie.
'Right,and now this natural method of pest control
is being copied all over the world.'
'Interesting,'said Debbie.'But now I really must go and...' 'Wait,'cried Simon.
'There's more.Do you know what is stronger than steel,
lighter than a feather and as elastic as a rubber band?'
'No. What is it?'
'It's the silk that spiders make their webs with.
And scientists are trying to develop a material with similar properties.
They plan to use it in spacecraft,artificial organs like hearts,
and to make really bullet-proof vests.'
'I still think spiders are nasty,' said Debbie.
'Their bites are poisonous, aren't they? They're dangerous.'
'To insects, yes, but to people, rarely.
But even their poison is useful.
Doctors think it might be used to treat brain disorders in humans.'
'That's good news for you, then,'laughed Debbie.
'But seriously,I get your point, Simon.
We should try to understand things in nature and not destroy them.'
LISTENING
Understanding descriptions and identifying pictures
MORE LANGUAGE INPUT(Ⅵ)
Reading
Small creatures?
People often think that insects are small delicate creatures.
But in reality, they are tough animals.
As a group,they are much tougher than many bigger animals that we know well
such as birds and fish, cats and dogs.
Insects have six legs and three body parts.
Their antennae and shells help them to detect and protect.
Can you imagine that insects,
with their special body structure and power of senses,
destroy about 10% of the world's food supplies every year?
Insects have an ability to breed rapidly.
This enables them to develop large populations.
If you put all the insects in the world together,
they would weigh more than all the people
and the rest of the animals on the earth!
Small creatures?
Yes,but with enormous strength.
Listening
Food Web
All living things,except plants, depend on other living things.
They eat other species but are also eaten by still others.
They are part of a food chain or a food web inthe world of nature.
In this listening exercise,you will be asked to draw a food web.
Listen to the statements carefully. Fill the missing names of the living things in the boxes.
Then draw arrows to show what eats what.
Remember the arrows in a food web always point from food to feeder.