I was expecting one of the boys to get complete mastery of the word "the", then get the power of flight so he could leave the island. So disappointed.

"Shucks to your Ass-mar" Said Ralph, as his face grew white, his eyes lost focus, and a telltale buzzing began emanating from somewhere deep inside of him. His mouth drooped low and spread wide forming a horrifying O at least two feet in diameter. The buzzing became louder and more frantic, as thousands of flies began to spill from his mouth, hurtling towards the small, fat boy in front of him who even now was attempting, futilely, to run from the buzzing, angry, hungry swarm of flies.

"He truly is" said one of the other boys, glad not to be the object of Ralph's ire for once "the lord of the flies"

I don't remember it very well but I thought the title was a reference to something hypothetical one of the kids thought of

Like they saw something they didn't fully understand and extrapolated that the thing they were seeing was the lord of the flies