Hemizygous larvae hatch somewhat later than their wild-type counterparts. They appear small and flaccid and move poorly. Shortly after hatching, the larvae move at 60% the rate of their wild-type counterparts, by 24 hours after hatching movement is reduced to 25% of wild type, and by 48 hours after hatching the larvae are immobile. Larval growth does not occur. One day old larvae have muscle defects; large areas where the muscle filaments are disorganised are seen using electron microscopy. Myofibrils are grossly disorganised in older larvae. Rhabdomeres within homozygous clones in the eye appear normal in size, density and morphology.

Phenotype of homozygous germ line clones demonstrates is there is no maternal effect.