Embryos expressing oc^Scer\UAS.cWa under the control of Scer\GAL4^{nos.bcd3'UTR.T:Scer\GCN4} (where Scer\GAL4^{nos.bcd3'UTR.T:Scer\GCN4} is provided maternally) show 60% embryonic lethality. Only a few embryos survive the larval stages and become adults. 48% of the embryos show a weak distortion of the pharyngeal wall and defects in the mouth hooks, mostly lacking the internal part. Most of the remaining embryos (51%) show head involution defects. The number of stomatogastric nervous system precursor invaginations is drastically reduced in most embryos. Most surviving larvae derived from embryos expressing oc^Scer\UAS.cWa under the control of Scer\GAL4^{nos.bcd3'UTR.T:Scer\GCN4} (where Scer\GAL4^{nos.bcd3'UTR.T:Scer\GCN4} is provided maternally) have feeding problems, since food never reaches the midgut. In most larvae, the food is engorged at the caudal end of proventriculus and the gastric caeca.