Female germ cells homozygous for vir4 can complete oogenesis. Females carrying these homozygous germ line clones produce eggs but when mated to vir+ males no larvae hatch. This phenotype is rescued if the homozygous germ line clones are induced in females carrying vir+t10. Whole larval gonads of the genotype XY ; vir4/Df(2R)vir130 form sperm after they are transplanted into the abdomen of adult females.
Male homozygotes and male transheterozygotes with other EMS induced vir mutations die during larval or pupal stage, very few male escapers are present. Transheterozygotes with virts transform XX animals into intersexes at 29oC. Sxl+/Sxl+;vir4/virts and Sxlf1/Sxl+;vir4/vir+ are viable but doubly heterozygous Sxlf1/Sxl+;vir4/virts females are lethal.