In Chapter 5 we see a meeting of the boys who come together to discuss their failure to accomplish certain tasks (namely keeping the signal fire going) but also their fear of "the Beast". It is interesting to note that this fear stems from rumours and dreams, but the fear threatens to drive the boys, and especially the smaller ones, to the point of hysteria. Percial reports to Jack that the beast "comes out of the sea" which then prompts Maurice to comment on how there are sea creatures that we know nothing about. He says:
My daddy says there's things, what d'you call'em that make ink - squids - that are hundreds of yards long and eat whales whole.
No mention is made of what the Beast might eat specifically, but the obvious suggestion is that the Beast would be able to eat the boys themselves, and perhaps especially the little ones.
....Then Piggy held out his hand. 'I don't agree with all Jack said, but with some. 'Course there isn't a beast in the forest. How could there be? What would a beast eat?'
'We eat pig.'
In Chapter 5 of "Lord of the Flies" as the boys discuss their fear of the beast, the logical Piggy tries to convince that a beast cannot exist since it has nothing to eat, but the boys reply that it, like them, can eat the feral pigs on the island. That they call out Piggy's name after saying the common noun pig is significant. For, this heckling of Piggy foreshadows the cruel death of the Piggy and the death of the rational element as the predatory, evil nature of the boys surfaces later in the novel. The beast, which is the inherent evil in the boys, can eat what they eat since it is, indeed, they.