Possible Clues:

• It's matured and gone off? Initially, yes
• Fully-grown insect
• Cicada's stage
• Winged insect — amigo (anag)
• Ideal notion of this person's past
• Developed form of life — the writer’s, in the past
• Maybe comma adding nothing to one publication
• I am past the final stage of development
• Adult insect post-metamorphosis
• Mature insect, one initially misidentified in the past