21 to 71% of ftz11/ftz13 flies are rescued to adulthood by ftz+tDa. 2 to 5% of ftz11/ftz13 flies are rescued to adulthood by ftzT263D. Larval cuticles of ftz11/ftz13 animals rescued by ftzT263D are indistinguishable from wild-type. ftz11/ftz13 flies are not rescued to adulthood by ftzT263A. Larval cuticles of ftz11/ftz13 animals carrying ftzT263A have pair-wise deletions of even-numbered parasegments. The penetrance of the phenotype is variable and defects in each ftz-dependent parasegment (PS) occur with a characteristic frequency. These range from the most to least frequently affected as follows: PS2 > PS6 > PS10 = PS4 > PS12 = PS14 > PS8.