Homozygous animals show growth defects; larvae hatch normally and initially show healthy behaviour, although with a constant delay in development compared to wild-type. The larvae are arrested at the first larval instar stage, although they can survive for longer than 7 days. The adult precursor cells and imaginal cells do not proliferate in homozygous larvae. The midgut epithelial cells of 5 day old larvae are smaller than in wild-type third instar larvae of the same age. The level of polyploidy in their nuclei is lower than wild-type. The number of adult midgut precursor cells is smaller in these larvae than in wild-type larvae, corresponding approximately to the number in wild-type first instar rather than third instar larvae. Salivary glands are smaller than in wild-type larvae and do not incorporate BrdU, indicating a failure in DNA replication. Homozygous pit¹⁰ larvae carrying pit^mod.PZ can survive to the third larval instar, although they have a delayed developmental schedule. Only a few of these larvae pupariate and adults are not produced. pit⁵/pit¹⁰ larvae develop normally, but with a delay. Although they pupariate, they never give rise to adults. Homozygous clones in the thorax are small and are only seen when induced late in development (at the end of the third larval instar stage). Homozygous clones in the wing imaginal discs are very small and composed of only a few cells.