Nomadic Phase
Certain insects spend time in both extended periods of settlement and extended periods of travel. During a period of travel, the entire group will continually move from one place to another. This is known as a nomadic phase. A nomadic phase may begin because a group of insects has a temporary need for additional resources that cannot be found in the area near the nest. Thus, the group must travel in search of these resources. Once the need for additional resources is over, the nomadic phase ends and the group settles again in one location.
听力材料：
The behavior of a particular kind of ant is a good example of this. These ants live together in colonies or and communities underground. They have these underground nests in the forest and Much of their life is made up of collecting food, finding food near the nest and bring it back to the colony.
Now when there are baby ants in the colony, there isn't enough food in that one location. Baby ants require a lot of nutrition, more food than can be found by just searching around near the underground nest. So colony needs to do something about this to make sure the baby ants have enough food to grow. So what they'll do is pretty dramatic. The entire colony will leave the nest. They'll pick up the baby ants and carry them along to a new location to find a new food supply. And once that food supply runs out, they'll move again to another location to ensure they have a continual fresh food supply. Often moving every night to meet the demanding nutritional needs of the baby ants. And this goes on until eventually the baby ants grow and no longer needs so much food. When this happens, the community events can finally stop moving from place to place and find a spot in the forest to make a new underground nest for the group to stay in and live.
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