You will find the symbolic Lord of the Flies in chapter eight. Jack and his hunters trap a sow and Roger is particularly cruel and twists his spear in the anus of the sow, causing the sow to scream in anguish:
They corner the wounded pig, and when she falls they are on her. Roger is particularly cruel, driving in his spear slowly by leaning his weight upon it until the sow screams in agony. Then Jack cuts its throat.
Jack smears the pig's blood over Maurice and then he separates the from the sow's body. He then hangs the head on a stick. This pig's head becomes the Lord of the Flies:
They decapitate the sow and leave its head impaled on a stick sharpened at both ends as a sacrifice for the beast. “The silence accepted the gift and awed them. The head remained there, dim-eyed, grinning faintly, blood blackening between the teeth.
The sow's head just hangs there. It is symbolic for the evil that is within Jack and his hunters. Simon sees the sow's head and has a conversation with it. The Lord of the Flies tells Simon that everything is a bad business:
Simon now sits and contemplates the head as it drips guts and draws flies. “The half-shut eyes were dim with the infinite cynicism of adult life. They assured Simon that everything was a bad business.”
Simon looks at the sow's head and determines it is the beast. It is a blob of bleeding guts which is swarming with flies:
“the pile of guts [that] was a black blob of flies that buzzed like a saw.” He ignores the flies that, sated from the pig, land on him and drink his sweat while “in front of [him] the Lord of the Flies hung on his stick and grinned.” Finally Simon looks the pig in the eye and sees the true beast.