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Look at the excerpt from paragraph 5.

(5) Maybe we had gathered the whole mosquito product of many acres. This is shown by the facts that if one rushes through thick bushes for a distance, into a clear space, the mosquitoes seem absent at first. One must wait a minute or so to gather up another legion. When landing from a boat on the Northern Lakes there are comparatively few, but even in a high wind, a walk to the nearest hilltop results in once again moving in a cloud of tormentors.

How does this paragraph refine the author's idea about mosquitoes?

The author refines his idea by