"A Bug's Life" is a relatively straight retelling of Kurosawa's "The Seven Samurai," except of course that the characters are bugs. Idealistic young ant Flik is a sweet-natured dreamer and inventor. But his innovative thinking makes him an outcast when one of his inventions goes awry and destroys the food sacrifice that the colony makes annually to a gang of grasshopper hooligans led by the sinister Hopper. Disgraced, Flik is sent to look for "warrior...