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.
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.