Maternal expression of one copy of bin3^EY11308 under the control of Scer\GAL4^{mat.αTub67C.T:Hsim\VP16} results in defects in egg development (only 47% of the eggs produced initiate development) and in embryogenesis (65% of the embryos that initiate development show embryonic lethality). The mutant embryos that develop show a high penetrance of head defects, ranging from a failure of head involution to a complete absence of head structures, and often have strong segmentation defects. Undeveloped embryos derived from females expressing bin3^EY11308 under the control of Scer\GAL4^{mat.αTub67C.T:Hsim\VP16} show dose-dependent ventralisation, with completely fused dorsal appendages at a frequency of up to 5%.