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 ftz 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 lacZ reporter.