What is the irony in The Lord of the Flies

Considering William Golding's Lord of the Flies as a whole, the greatest irony is that the boys, who escape war and death by their saving arrival on a paradisiacal island far removed from the "evils of society" degenerate into worse creatures than they would have become if they had remained in their homeland.  For the "evils of society," ironically, lie within the human heart; evil is inherent in man, the "beast" is he, as Simon discovers.  So, just as in the Garden of Eve where it is Adam and Eve who commit the evil act, so, too, is it in Lord of the Flies.  Interestingly, Golding eliminates any Eve from the situation to prove that the evil is inherent and not caused by any temptress or anyone else that can be blamed.  As the Lord of Flies hangs in space before Simon, it says,

'Fancy thinking the Beast was something you could hunt and kill!' said the head.  For a moment or two the forest and all the other dimly appreciated places echoed with the parody of laughter.  'You knew, didn't you?  I'm part of you?  close, close, close! I'm the reason why it's no go?  Why things are what they are?'