The dorsal longitudinal muscles of the indirect flight muscles are denatured and the flies are rendered flightless. Dorsoventral muscles are wildtype.
Mutants have defective dorsal longitudinal muscles (DLMs) with considerable thinning of the fibres. The fibres are disrupted, appear to be loosely bundled and show degeneration in the posterior region of the thorax. All six fibres of the DLMs are formed. The dorsoventral muscles show slight thinning but are otherwise normal.