Required for activity of the M3 pharyngeal motor neuron. In the anterior pharynx, expressed in the I3 interneuron, the NSM and M3 motor neuron pairs, the three m2 muscle cells and the three e2 epithelial cells (at protein level). Earliest expression is detected in late gastrulation (at protein level). Expression is strongest in elongated embryos and early larvae. Mutants lacking the homeobox domain are viable and fertile but proliferate slightly more slowly than wild-type due to retarded larval development and reduced brood size. About 20% appear starved as they are shorter, thinner and paler at all stages with severely affected adults bearing only a few eggs. M3 neuron activity is decreased. Can substitute for ems in D.melanogaster ems mutants, partially rescuing the mutant phenotype. Belongs to the EMX homeobox family.