Lethal phase is during the third larval instar stage. Homozygous larvae contain rudimentary imaginal discs, but the disc primordia do not grow during larval development. Testes and ovaries are smaller than normal and cell number in the central nervous system is reduced. Mitotic abnormalities are seen but salivary chromosomes are apparently normal. Mutant gonads do not survive metamorphosis when implanted into wild-type larvae. Homozygous cuticular clones appear to develop normally. Mutant larvae support growth of implanted wild-type discs.