Lucilia cuprina has a large, heterochromatic X chromosome with few genes. In a study recently published in PLoS ONE, we found that endogenous genes on the X chromosome are dosage compensated, that is expressed equally in males and females. However, transgenes that land on the X chromosome are more highly expressed in females, showing little if any dosage compensation. It appears that endogenous genes can respond to the dosage compensation mechanism but recently arrived transgenes cannot. Rebecca was first author and Esther coauthor on this study.