Transgenic construct used to investigate factors that determine the effectiveness of the gypsy insulator. Encodes two divergently transcribed reporters; a w minigene expressed under the control of its own promoter and lacZ driven by a Scr promoter. A 340bp gypsy insulator fragment and the AE1 enhancer from the ftz gene have been inserted in between the two divergent promoters, such that the insulator fragment is proximal to the w minigene reporter.