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As they migrate (迁徙), butterflies and moths choose the winds they want to fly with, and they change
their body positions if they start floating in the wrong direction. This new finding suggests that insects may
employ some of the same methods that birds use for traveling long distances. Scientists have long thought
that insects were simply at the mercy of the wind.
Fascinating as their skills of flight are, migrating behavior has been difficult to study in insects because
many long distant trips happen thousands of feet above ground. Only recently have scientists developed
technologies that can detect such little creatures at such great heights.
To their surprise, though, the insects weren't passive travelers in the winds. In autumn, for example,
most light winds blew from the east, but the insects somehow sought out ones that carried them south and
they positioned themselves to navigate directly to their wintering homes.
Even in the spring, when most winds flowed northward, the insects didn't always go with the flow. If
breezes weren't blowing in the exact direction they wanted to go, the insects changed their body positions
to compensate. Many migrating birds do the same thing.
The study also found, butterflies and moths actively flew within the air streams that pushed them along. By adding flight speeds to wind speeds, the scientists calculated that butterflies and moths can ravel as fast as 100 kilometers an hour. The findings may have real-world applications. With climate warming, migrating insects are growing in number. Knowing how and when these pests move could help farmers decide when to spray their crops.
1. What's the main idea of the text?
A. Insects migrate with the seasons.
B. The wind helps insects greatly in migrating.
C. Windsurfing insects have real direction.
D. Scientists have trouble in observing insects.
2. Scientists originally thought that _____________.
A. insects always waited for their favorable winds
B. insects chose the winds they wanted to ride
C. insects were just blown about by the wind
D. insects positioned themselves in the winds
3. It is not easy to study the migrating behavior of the insects because _____________.
A. the little creatures can fly very fast
B. they have no regular migrating courses
C. the wind's direction is hard to foresee
D. their flight is long and high above ground
4. We can learn form the text that _______________.
A. insects fly in the way birds do
B. insects travel more easily in autumn
C. insects never position themselves when flying low
D. insects rest a lot when the wind pushes them along
