As the novel progresses, flies become more prevalent in the text, just as the sins of the boys increase and the death toll rises. Initially, the boys think that living on an island with no parents will be joyful and the greatest time of their lives. Eventually, reality set in and a form of order begins to form, something many of the boys despise. Over time, the fun island life turns deadly, as conflict arises between the children and a many of the boys become bloodthirsty. While sows initially fulfilled their thirst for blood, Jack and his followers eventually move onto bigger targets: Simon and Piggy.
The first real sight of flies occurs after Jack sets out a pig head on a stick for the beast. The flies surround the dead carcass and the buzzing sound is rampant. As the novel progresses, more flies appear, always in the wake of someone or something's death. The flies begin shape the idea of savagery that forms within the boys and represents all the deaths that occur within the realm of the island.