The general name Lord of the Flies gets its original inspiration from an Old Testament biblical name. Beelzebub is the name of a "pagan" god from a story involving King Ochozias. The god was an oracle that people went to for answers (like any oracle). It is thought that Beelzebub was a god of sacrifice or sun, hence the translation to Lord of the Flies--flies either attracted or brought about by each. Later, in the New Testament, there is an evil demon or spirit with a similar sounding name to Beelzebub, and so Beelzebub is often refered to as a demon character. It is referenced as thus in the band Queen's famous song "Bohemian Rhapsody."
In the story, the pig head speared on the end of a stick is called The Lord of the Flies. It is a key symbol of the feral wildness that has come forward in all of the boys since they crashed from civilization.
It also produces an interesting contradiction of terms when considering the positive conotation or associations with the word Lord and the negaitve conotation of the word flies.