The history of transposable elements over evolutionary time can often be partially reconstructed on the basis of genome analysis. In this study, we identified and extensively characterized the NLTR BS retrotransposon in 12 sequenced Drosophila genomes, by its sequence diversity within and among genomes, its degeneration pattern and its transcriptional activity. We show that the BS element has a variable copy number and patchy distribution within the Drosophila genus, that it is at distinct stages of the evolutionary cycle in the different Drosophila species and that its evolution is characterized by vertical transmission and by bursts of transposition in certain species.