Fruit fly. Macrophotograph of the pomace fly, Drosophila melanogaster, commonly but inaccurately known as the fruit fly because of its appearance on overripe fruit. Extensive investigations using this species resulted in fundamental genetic discoveries in the early part of this century. The fly is easily accessible to study. It is small & reproduces rapidly & in large numbers. The number of chromosomes per cell is small and hence manageable for investigative purposes. The chromosomes are large & easily identified. Finally, Drosophila mutates spontaneously. Magnification: x6 at 35 mm size.