In the genus Drosophila, mating is the result of a courtship involving several sensory modalities. A key component is the production of song made by the male. These sounds, directed towards females, are produced by wing vibration. They consist of sine song and intermittent pulse trains varying in length. The pulses are separated by interpulse intervals (lPI), whose mean values are characteristic of each strain. The aim of this work is to compare the development of the species specific song in two related strains Drosophila melanogaster and D. simulans. Is there progressive maturation or a sudden establishment of the song pattern? Is the pattern common at the first stage but divergent afterwards, according to each strain? Males were placed with mature female at six precise stages of maturation (12, 17, 22, 27, 33 hours and mature (4 days)) and the courtship was recorded. In the melanogaster strain, frequencies of pulse and sine are very close to those of the mature stage as early as 12 hours but the rhythm of emission differs. It is only at 27 hours that the mature rhythm appears and consequently that males succeed in mating. In simulans, experiments are under way.