The title of Golding's celebrated novel Lord of the Flies refers to the severed pig's head that Simon interacts with while hallucinating, which symbolically represents the presence of evil on the island. The title also alludes to the mythological demon Beelzebub, whose name is translated literally as "lord of the flies."

The evil connotation of the title and its association with the severed pig's head corresponds to Golding's primary theme regarding the wicked nature of mankind, which is confirmed during Simon's enlightening experience in the forest. In the story, the British boys stranded on an uninhabited island revert back to their primitive instincts and develop into cruel, bloodthirsty savages. Their dramatic transformation is thematically significant and suggests that the veil of civility is extremely thin.

In chapter 8, Golding refers to the severed pig's head as the Lord of the Flies, which speaks to Simon in his secluded spot and confirms his belief that the beast is not a tangible creature. The Lord of the Flies tells Simon that it is the reason "it's no go" and says, "Fancy thinking the Beast was something you could hunt and kill!"

As a Christ-figure, Simon possesses hidden knowledge and wisdom regarding the true identity of the beast and is the only boy who recognizes that it is not a physical monster. The Lord of the Flies simply confirms Simon's belief and influences him to climb the mountain to examine the beast. In addition to the important message Simon receives, the flies surrounding the pig's head are associated with death, decay, and corruption, which reflect the boys' current condition and diminishing civility on the island.

The title of William Golding's novel "Lord of the Flies" refers to the incident in chapter 8 when Simon has a vision while experiencing a prodrome to an epileptic seizure. Simon, the most sensitive and insightful of the boys, likes to get away by himself in a favorite hideaway in the jungle. After Jack and his hunters kill a sow, they cut off its head and plant it on a stick right outside Simon's retreat. The pile of guts attracts a mass of flies, and the flies, after gorging on blood, come and land on Simon. As Simon turns to face the pig's head, he imagines it as the Lord of the Flies since it seems to be in kingly authority over the buzzing insects.

"Lord of the Flies" is a translation for Beelzebub, a demon mentioned in the New Testament as chief of the demons. Thus it represents the epitome of evil. Simon enters into dialogue with the "pig's head on a stick," as he calls it, trying to diminish it. The head tells him that it is "the Beast," which actually reflects a sentiment Simon had previously when he tried to tell the boys, as they attempted to decipher the nature of the beast, that "maybe it's only us." The head goes on to tell Simon, "I'm part of you. Close, close, close!" This reveals Golding's primary theme of the novel, namely, that the reason societies fall apart is because of "mankind's essential illness," the moral depravity or evil that is within each person.

Using "Lord of the Flies" as the title of the novel points readers' attention to this key scene, helping readers focus in on the message of the book. 

The phrase "lord of the flies" is often associated with the mythological figure of Beelzelbub. 

The name Beelzelbub, from the Hebrew, literally translates to mean "lord of the flies" and this figure is depicted in mythology as a demon in the form of a fly. More specifically, Beelzebub is a name used for "the devil" in some ancient Jewish and Christian texts (and the name is associated with the enemy god, Baal).  

So, in addition to its meaning within the text, the title also references these ideas drawn from well-known mythology. One question then becomes, why would Golding title his novel with a reference to the devil? 

According to scholars of Hebrew literature, the figure of the fly (and its associated god-figure) represents impurity and evil. Perhaps a more compelling view of the use of this reference in the novel's title is to see the idea of Beelzebub as a representative of animalistic, sanguine and brute impulses that stand counter to notions of restraint, civility and tolerance. 

We might argue that this conceptual conflict animates the action of Golding's novel.

"Ralph’s reliance on reason and logic contrasts with Jack’s steady descent into savagery. They thematically represent opposite aspects of human behavior" (eNotes).

The impulse toward expressions of savagery is repeatedly indulged by Jack's character and those who eventually follow him. The symbol of this brute behavior is the boar's head, which "speaks" at one point. 

"Fancy thinking the Beast was something you could hunt and kill!" said the head. 

Considering everything above, we might ultimately suggest that the meaning of the title is a commentary on the inherent evil that exists in human kind. Civilization cannot eradicate evil impulses and savage tendencies but can only mask them or offer alternatives in controlled settings. Take away the controls and the mask falls away. 

The title in Lord of the Flies actually refers to the boar’s head idol that Simon envisions, which is surrounded by flies.  It also metaphorically refers to the rot and decay of society represented by the break-down of the boys’ civilization.

The flies themselves are described in a very specific way, as a “black blob” that “buzzed like a saw” (p. 198).

Simon, the Christlike thinking child, becomes enchanted with the flies.

They tickled under his nostrils and played leapfrog on his thighs. They were black and iridescent green and without number; and in front of Simon, the Lord of the Flies hung on his stick and grinned. (ch 8, p. 198)

Since the boys spend so much time hunting or thinking they are hunting, the fact that the Lord of the Flies is the boar’s head is particularly symbolic.  The boys’ society has retrogressed completely to a more heathen state.

In William Golding's Lord of the Flies, what does the title refer to?

Jack's hunting gang takes a severed pig's head and sticks it on a stake in the middle of the forest as an offering for the "beast."  The head is battered and bloody and soon collects its fair share of flies.

After a while Simon wanders into the spot in the woods where the head is and becomes mesmerized by its grotesque appearance.  He even thinks that the head is talking to him in a "Lord of the Flies" voice.  It declares that Simon will never be able to escape him because he is inside all people.

Lord of the Flies is also a common euphemism for Satan.