By starting out with Gregor's metamorphosis into a bug, The Metamorphosis plays around with some interesting questions as to the significance of transformation. We're never told exactly how or why Gregor got transformed into a vermin, although there are hints that Gregor may have committed some sexual or financial misdeeds. Moreover, Gregor seems to change in other ways during the course of the novella. His metamorphoses have a rippling effect on the other characters as they modify their own behavior in response to his new form. These transformations draw attention to the ways that people change under pressure, not just physically but psychologically and emotionally as well, to the point where they may no longer recognize themselves.
While Gregor's initial transformation into a vermin may be an arbitrary event, his devolution into a refuse-covered carcass shows how the other characters have an equally transformative impact on Gregor through their mistreatment of him.
Gregor continues to change after his transformation into a vermin, as his new body influences his mental life through new needs and behaviors.