AbstractA recombinant plasmid vector was constructed in which the bacterialLacZgene was placed under the control of aBombyx moribaculovirus early promoter. The vector proved to be active in transfected cultured dipteran and lepidopteran cells. Co‐transfection carried out with this recombinant plasmid vector and a plasmid containing the hygromycin phosphotransferase gene followed by selection with the antibiotic hygromycin B, resulted in stable transformation of culturedDrosophila melanogasterSchneider 2 cells. Southern blot analysis of the host cell's genomic DNA in combination with chromosomalin situhybridization demonstrated that multiple copies of both plasmids were integrated in the host cell's genom