What metaphors are used in The Voyage of the "Dawn Treader" by C. S. Lewis?

Edmund states that if there is a wasp in the room he would like to be able to see it and says this in reference to the dragon that Lucy is hoping will skulk away and leave them alone. This is a metaphor for wanting to be able to see the threat or the enemy because a wasp that one cannot see is the one most likely to sting.