Who gave the fly the idea in The Trick of the Fly?

Not sure. The Fly's Trick is a novel written by william golding, which tells the story of a group of English students living on a desert island. In the novel, it is not explicitly mentioned who gave the fly the idea. But the characters in the novel all have their own thoughts and actions, and their survival and decision-making on a desert island are influenced by their own background and experience. So it can be said that the thought and behavior of the whole group led to the appearance and influence of flies.