Hmmmm, in looking at Gregor's metamorphosis, we can consider a few different things. First, he transforms into an insect (you cite that he's pictured as a cockroach). How does Gregor's pre-transformation life parallel the life of an insect? Well, insects generally live in working colonies; certain workers (think ants and bees) are the workers, while others take no part in caring for the group. Gregor is the worker "bee" per se.
Once Gregor figures out that his work goes unappreciated and is expected, he tranforms and the family begins a necessary role reversal. Unfortunately, his isolation and new role leave him completely alone. Everyone in the family moves on, but Gregor is left with nothing....... he doesn't even have his family anymore.
As for the second part of your question, are you referring to the time in which Kafka wrote for him personally?