How is the loss of innocence shown in Lord of the Flies?

In Golding's novel Lord of the Flies, the boys quickly lose their innocence during their time on the island. Golding shows the downward spiral from relative innocence to depravity in numerous ways, including the boys' clothing, the hunting, and the deaths. At first the boys wear clothing that associates them with their British schools. British choir boys are a symbol of innocence with their sweet-sounding childish voices and dignified demeanor. When Jack's choir boys first appear, he is making them march across the beach fully clad in their black choir robes. They immediately take those off, and before long most of the boys are running around the island barely clothed. That doesn't fully represent loss of innocence, though. Jack finds a new way to clothe himself, namely with paint. Wearing paint instead of clothing, Jack finds himself "liberated from shame and self-consciousness." He goes even further. At his feast in chapter 9, Jack wears a garland. Showing a repudiation of all orthodox religious adherence, "Jack, painted and garlanded, sat there like an idol." 

Second, the way Golding portrays hunting shows the boys' loss of innocence. In chapter 1, the boys find a piglet caught in a thicket. Although Jack raises his knife to kill it, he can't bring himself to do so "because of the unbearable blood." He is still too innocent. But when the boys kill their first pig, Jack experiences

"the knowledge that had come to them when they closed in on the struggling pig, knowledge that they had ... imposed their will upon it, taken away its life like a long satisfying drink."

This is like the knowledge of good and evil that Adam and Eve experienced when they lost their innocence in the Garden of Eden. Later Jack is able to play with the spilled blood, and the boys are "wedded to [the sow] in lust, excited by the ... dropped blood." Ultimately, Jack has descended so far away from innocence that he actually hunts Ralph, intending to kill him like a pig and impale his head on the stick they have sharpened at both ends.

Finally, the deaths that occur on the island show the fall from innocence. The first to die, the boy with the birthmark, is killed because of negligence, a crime that, although horrible, is nevertheless not a crime of passion. Simon, the next to die, is murdered by manslaughter by the mob of boys. The crime is intentional, but not premeditated. Piggy's death is premeditated, and Jack rejoices afterward, showing a complete loss of innocence. The boys then hunt Ralph, intending to kill him, planning out his murder with no glimmer of conscience restraining them. 

The loss of the boys' innocence can be traced in several ways through the novel, especially through the boys' clothing, their reaction to hunting, and the way that deaths occur.