The reason Gregor Samsa turns into a bug in Franz Kafka's "The Metamorphosis" is never explained in the story. The story begins with Samsa waking up to find that he has turned into an insect. The rest of the book deals with his attempts to reconcile the fact that he is a human in an insect's body.
"The Metamorphosis" was written by Kafka in 1912 and published in 1915. It is primarily set in the apartment that Samsa shares with his family. A major theme throughout the novella is alienation, as Samsa's family attempts to remove him. In the end, he dies alone after he is injured by his father.