The Samsa family no longer had a use for Gregor. The love that was thought to be there began to show. This was a immature love, which had no meaning. His sister made a cruel decision that the rest of the family, excluding Gregor, acted upon. They decided to exterminate Gregor. Apples were thrown at Gregor by his father. One of those apples was thrown and embedded into his back. This apple could not be removed and rotted in his beetle flesh that could not heal. The rotted apple of evil and cruelty in the flesh is what killed Gregor.
In the Metamorphosis, Kafka reminds us of how often certain people and things are taken advantage of. He reminds us of how cruel this society can towards each other, especially in a time of emotional hurt and need. He points out that we all can be mislead and blinded by the cruel activities that society