45% of homozygotes die in late embryogenesis with no obvious morphological defects and a normal cuticle. 55% of homozygotes hatch into larvae and live for 4-8 days, but they remain very small. These larvae move and feed normally and have no morphological defects. The growth of these larvae closely resembles that of sucrose-fed wild-type larvae, which remain arrested in the first instar stage without protein accumulation. Homozygous larvae show greatly reduced BrdU labeling, indicating that DNA replication is reduced, at 0-24 hours after hatching compared to their heterozygous siblings. Between 24 and 48 hours after hatching there is no DNA replication in homozygous larvae, except in the mushroom body neuroblasts in the brain. Homozygous clones induced 24-24 hours after egg deposition (AED) do not survive (clones are not seen in third larval instar imaginal discs or adults). Homozygous clones induced later in development (110-114 hours AED) survive. These clones produce occasional defects in some chemo- and mechanosensory bristles of the anterior wing margin. The defects include deletion and disruption of the bristles. Cuticle defects and rough eye phenotypes are also seen. Early induction of homozygous clones in a Minute^- background results in pupal lethality. Females containing homozygous germ line clones do not produce viable eggs. Malformed, deflated eggs are sometimes laid. Oocytes in homozygous germ line clones often contain incorrect numbers of nurse cells (the number ranges from 0 to more than 30), suggesting a defect early in oogenesis when cysts pinch off from the germarium. Germ line proliferation, DNA endoreplication and overall growth do not appear to be completely blocked in the cysts.