Transgenic construct that contains an SV40 transcription terminator at the 5' end (to prevent possible transcription passing through the 5' end of the transgene when it is integrated into the genome), 5xUAS regulatory sequences, the y transcription unit and a mini-w marker (with the w gene transcription terminator). The y promoter is flanked by a pair of FRT sites. A loxP cassette containing the w eye enhancer has been inserted into the intron of the y gene.