Approximately one-third of homozygous embryos show a severely disrupted muscle phenotype, with the muscles often appearing as round balls or thin disorientated fibres, whereas in less severe cases, various subsets of muscle fibres are missing.

nau^armGFP/Df(3R)Exel6195 embryos show a range of muscle disruptions. The gut constriction pattern is often abnormal with fewer or misplaced constrictions than normal.

Approximately 70% of homozygotes die during the embryonic or larval stages. Those larvae that survive are weak and move in an uncoordinated fashion, often staying in one position, oscillating back and forth. Slightly more than half of the pupae hatch, with extended eclosion times of more than 12 hours compared with a few minutes for normal pupae, whereas the remaining pupae do not open, or flies only partially exit the pupal case. Most of the flies that hatch remain at the bottom of the vial with shriveled wings, unable to move or stand, and eventually die. Surviving adult females develop distended abdomens filled with eggs that remain held for more than 20 days, even when they are mated in groups or in single crosses. The ovarioles of mutant females have egg chambers that are uniform in size and smaller than normal (unlike the clear progression in egg chamber size seen in wild-type ovarioles).