What does 추파를 던지다 mean?

Today, I came across the following expression:

가까이선 아양, 멀리서는 추파 던지는 년이다.
A woman who flirts when up close and gives amorous glances when far away.

The above sentence is a way of referring to "a loose woman." (년 is a contemptuous way to refer to a woman. You should probably avoid using it.)

추파(秋波) literally means "autumn wave," which I think is referring the fields of grain stalks rippling in an autumn breeze. However, I do not know how "throwing autumn waves" (추파를 던지다) came to mean "throwing amorous glances"?