How does the author use metaphor in the novel, Three-Martini Lunch?

Cliff’s younger brother’s bug collection included a cicada (a large winged insect) that was molting (shedding its shell). He shows it to Cliff just before he leaves for his journey to San Francisco, and Cliff thinks to himself that he is molting, a metaphor for the way he is shedding his past as he travels to his future. He once again returns to the metaphor at the end of the novel after losing Joey, realizes that he was wrong, and he is not like the cicada itself, shedding its shell and leaving it behind. Rather, he is the molted empty shell, clinging to the memory of his time with Joey in the houseboat in San Francisco.