Drosophila’s widespread use in genetic studies is no accident. The fruit fly has a number of characteristics that make it an ideal subject for genetic investigations. Compared with other organisms, it has a relatively short generation time: fruit flies complete an entire generation in about 10 days at room temperature, so several generations can be studied within a few weeks. Despite this short generation time, D. melanogaster possesses a complex life cycle, passing through several different developmental stages, including egg, larva, pupa, and adult. A female fruit fly is capable of mating within 8 hours of emergence from the pupa and typically begins to lay eggs after about 2 days. Fruit flies also produce large numbers of offspring, laying as many as 400 to 500 eggs in a 10-day period. Thus, large numbers of progeny can be obtained from a single genetic cross.

Another advantage is that fruit flies are easy to culture in the laboratory. They are usually raised in small glass vials or bottles on easily prepared, pastelike food consisting of bananas or corn meal and molasses. Males and females are readily distinguished and virgin females are easily isolated, which facilitates genetic crosses. The flies are small, requiring little space—several hundred can be raised in a half-pint bottle—but they are large enough for many mutations to be easily observed with a hand lens or a dissecting microscope.

Finally, D. melanogaster is an organism of choice for many geneticists because it has a relatively small genome consisting of approximately 180 million base pairs of DNA (only about 5% of the size of the human genome). It has four pairs of chromosomes: three pairs of autosomes and one pair of sex chromosomes. The X chromosome (designated chromosome 1) is large and acrocentric, whereas the Y chromosome is large and submetacentric, although it contains very little genetic information. Chromosomes 2 and 3 are large and metacentric; chromosome 4 is a very small acrocentric chromosome. In the salivary glands, the chromosomes are very large, making Drosophila an excellent subject for chromosome studies. In 2000, the complete genome of D. melanogaster was sequenced, and this was followed in 2005 by the sequencing of the genome of D. pseudoobscura. The genomes of several different species of Drosophila have now been sequenced. Drosophila continues today to be one of the most versatile and powerful of all genetic model organisms.