There are several metaphors within Chapter Two of Lord of the Flies:
"He was a shrimp of a boy, about six years old, and one side of his face was blotted bout by a mulberry-colored birthmark."
This metaphor compares the boy to a shrimp, which helps the reader understand exactly how small he is. This sets up an interesting comparison of size when the boy proclaims that there is a "beastie" problem on the island that must be resolved.
"On one side the air was cool, but on the other the fire thrust out a savage arm of heat that crinkled hair on the instant."
This metaphor personifies the fire, comparing the dancing flames and the heat they give off to the aggressive movement of a human arm being extended.
"The sun in the west was a drop of burning gold that slid nearer and nearer the sill of the world."
This metaphor compares the sun to gold and the horizon it is setting upon to a shelf-like structure. It is a picturesque description given the fact that the boys are about to encounter darkness on the island.
"The squirrel leapt on the wings of the wind and clung to another standing tree, eating downwards."
This metaphor is actually introduced by an earlier simile ("One patch touched a tree trunk and scrambled up like a bright squirrel.") and compares the growing flames which are consuming the tree line to a squirrel gnawing away.
This is the chapter where the boys decide they need to build a fire on the mountain so that they can capture the attention of any ships that might be passing by them. There are several metaphors that refer to the fire, flames and logs that they use to make the fire. For example: "smoke on the mountain" and "platform of forest" and "the grotesque dead thing" and "breeze was a river of sparks" and "beard of flame" and "tree of sparks" - all of these apply to the fire or the materials that they use to create the fire. There are other non-fire related metaphors, but these stand out. Earlier, the little boy that is afraid of the "beastie" is referred to as "a shrimp of a boy" and later in the chapter there is "the sun in the west was a drop of buring gold". If you read on towards the end of this chapter, you will see additional fire metaphors - there is a simile that compares the fire to a "squirrel" but then afterwards, this image is intensified with additional "squirrel" metaphors that compare the smoke from the fire to a squirrel.