Drosophila Melanogaster has been extensively studied for genetic investigations due to its ideal characteristics for the study of animal development. This species contains characteristics such as small size, approximately 1mg, which allows testers to study many at one time. In addition to being small, they can survive in small spaces, which means numerous tests can be conducted and many different mutant stocks can be maintained. Many tests are conducted in small tubes, as fruit flies do not need much space for living. Moreover, the Drosophila Melanogaster has a very simple food plan, meaning it is not hard to take care of these species during testing. They also have a short life cycle of 12 days, which allows scientists to study the life cycle of a fruit fly, and perform test crosses, very easily. Room temperature is an important factor that allows their life cycle to be completed within the 12 days. A fruit fly undergoes metamorphosis, which means it has three stages of development before reaching adulthood. The three stages consist of: egg, larval, and pupal. Egg: Fruit flies are capable of laying up to 500 eggs during their lifetime. Most eggs are laid in fruit or other decaying material. The optimal temperature for laying an egg is 75-80 degrees Fahrenheit, also known as room temperature. Larva: Larva are the small worm-like stages of a fruit fly. Larvae feed on the decaying material in which they were hatched, and tend to consume a lot of food in order to prepare for their next stage, the pupal stage. Larvae shed their skin in order to increase their size. Pupal: Pupating is a resting stage for the larvae to increase in size and begin to form into the adult fly. Fruit fly pupae are small and unnoticed. This is the last stage before the fly reaches the adult stage. Above is an image representing the life cycle of a fruit fly, starting as an egg on day 1, and ending as an adult on day 10 or sometimes 12. The fruit fly spends the longest time as a larva, growing and increasing its size to prepare for adulthood. Background Studies of the Fruit Fly: Thomas Hunt Morgan was one of the well known biologists who had studied the Drosophila in the early 1900’s. He was the first scientist to study genetic recombination and performed thousands of tests on the Drosophila. After test crossing many species of the fruit fly, his results confirmed the chromosomal theory of inheritance, which states that genes are located on chromosomes like beads on a string, and that some genes are linked. Illustrated above is Morgan’s experiment of the cross between the white eyed male fruit fly, and the red eyed female fruit fly. As the f1 generation is crossed, you can see that sex linked inheritance affects the f2 generation as one male becomes white eyed. This image is a better representation of Morgan’s conclusion.