Embryos that are homozygous for fs(1)pyr^Su(b) r^Su(b) and b^unspecified and originate from a female homozygous for these 3 mutations show reduced viability; most progeny die at early developmental stages. Embryos that are homozygous for fs(1)pyr^Su(b) r^Su(b)DK7 and b^unspecified and originate from a female homozygous for these 3 mutations show severely reduced viability. Newly laid eggs begin development normally, and early embryogenesis proceeds normally through the syncytial blastoderm, gastrulation and extended germ band stages. Abnormalities such as shrinkage of the embryo and lack of muscle contraction are seen near the end of embryogenesis and the majority of embryos die just before the eggs are due to hatch.