Transgenic construct used as a control in an enhancer-blocking assay. Contains a y reporter gene composed of 5' regulatory sequence that includes the wing and body enhancers and which has a deletion from -438 to -70bp, fused upstream of a genomic fragment containing the y coding region (this fragment also includes the y bristle enhancer in the y intron). The w+mC minigene is present downstream of the y coding region.