The Pit(1981)

Twelve year-old Jamie Benjamin is a solitary misunderstood boy in his preteens. His classmates pick on him, his neighbors think he's weird and his parents ignore him. But now Jamie has a secret weapon: deep in the woods he has discovered a deep pit full of man-eating creatures he calls Trogs... and it isn't long before he gets an idea for getting revenge and feeding the Trogs in the process!