"The Lord of the Flies" is another name for Beelzebub, the devil. Thus, the pig's head with flies around it symbolizes Beelzebub, the force of evil. Although Simon, a Christ-like figure who falls victim to the evil of the boys, recognizes the Beast, or the devil, he forces himself with "mouth labored," to say that this Lord of the Flies is merely a "Pig's head on a stick." But, Beelzebub acknowledges that Simon has intuitively has known all along where evil lies; namely, innately within the boys.
"You know perfectly well you'll only meet me down there--so don't try to escape!"
Certainly, at the beast's center lies man. The flies hover around the pig's head as they focus upon death by savagery, death by violence, and the destruction of what is beautiful and good as represented by the innocent Simon. For, just as the pig's head drips blood, in Chapter 9, Simon's blood stains the sand.
In chapter eight of Lord of the Flies, by William Golding, Jack and his hunters sharpen a stick at both ends and place the dismembered, bloody head of a pig on it. Jack knows his hunters, like nearly all the boys on the island, have a fear of some nameless beast; he hopes to allay some of those fears by this act. He tells his hunters that they are leaving a sacrifice to appease the beast, though the reality is that the creature Simon sees as Lord of the Flies is really just a pig's head jammed onto a stick. Symbolically, the pig's head is much more than that.
Simon has a hiding place where he goes to be away from everyone, and he is there when the hunters erect the faux sacrifice right outside of his secret hideaway. We know that Simon has a tendency to faint, and through the course of his conversation with the Lord of the Flies we have indications that this dialogue is not real but conducted in Simon's head. At the end of the conversation Simon faints.
The Lord of the Flies tries to intimidate and threaten Simon; he calls Simon "just an ignorant, silly little boy" and mocks Simon for thinking the beast is "something you could hunt and kill!" Golding uses this symbolic beast, the Lord of the Flies, to reveal the truth to Simon: they, the boys, are the beast. The Lord of the Flies says,
“You knew, didn’t you? I’m part of you? Close, close, close! I’m the reason why it’s no go? Why things are what they are?”
Before Simon faints, the Lord of the Flies warns Simon that he is not wanted on this island (because Simon represents the soul and spirit of man) and predicts that "Jack and Roger and Maurice and Robert and Bill and Piggy and Ralph" will kill him. And they do.
Thanks teachers! you are great