Normal and mutant fruit fly. Light micrograph (LM) of a normal and a mutant fruit fly of the species Drosophila melanogaster. The fly on the right is the natural, or wild type, known as Oregon R. The fly on the left is a mutant type with almost no wings. D. melanogaster has been used for many years in genetic studies because it is easy to raise in large numbers, reproduces rapidly, and many of its mutations are easy to spot under a low-powered light microscope. The adult flies are 2-3mm long. Magnification: x45 at 10cm wide