Reproduction in Drosophila is rapid. A single pair of flies can produce hundreds of offspring within a couple of weeks, and the offspring become sexually mature within one week (Lutz 1948).
As in all insect species Drosophila melanogaster lays eggs. The eggs are placed on fruit, and hatch into fly larvae (maggots), which instantly start consuming the fruit on which they were laid (Patterson and Stone 1952).
Male flies have sex combs on their front legs. It has been theorized that these sex combs might be used for mating. However, when these combs are removed it seems to have little effect on mating sucess (Patterson, et al 1943). (Lutz, 1948; Patterson and Stone, 1952; Patterson et al., 1943)