Homozygotes generally have normal wing phenotypes but can have raised/held-out wings. The number of dorsal longitudinal muscle (DLM) fibres varies (due to defects in the splitting of the DLMs during development), but usually only three are present, and the posterior ends of these fibres have degenerated (degeneration occurs a few hours before eclosion). The dorsoventral muscles (DVMs) are disorganised. Myofibrils appear to have a normal banding pattern except for a few breaks and gaps. The anterior ends of the DLMs are completely lost in ifm(2)RU3¹/Df(2R)Px1 flies. Homozygotes with expanded/raised wings are generally flightless, while most of those homozygotes with normal wings are have weak flight ability. Homozygotes have significantly reduced viability.