Rover the dog left a bone only half cleaned under the fence, and forgot to go for it again, so Mrs. Fly laid her eggs on it. In a day or two the eggs hatched out into tiny white creatures with no legs. They ate hard for a few days at the meat left on the bone, and then settled down and kept still while they changed into flies. When they broke their way out of their old skins you would hardly believe they had once been white and helpless, for now they were dark in colour, with wings that gleamed as they moved, and wonderful eyes and feelers and legs.