Homozygous animals show a delay in pupation; the third larval instar last 12-16 hours longer than normal. Development ceases at pupal stage P4(ii) in homozygotes. The imaginal discs and central nervous system are smaller than normal in homozygous larvae, but reach the normal size at pupation. Homozygous stage P4(ii) pupae show development of symmetrical lateral melanotic pseudotumours. These melanotic tumours are at sites of fusion of the thoracic imaginal discs (no melanisation is seen in regions of eye-antennal disc fusion).