The dorsal longitudinal muscles of the indirect flight muscles show a reduction in fiber number and muscular degeneration in anterior and posterior regions of the thorax. The flies are rendered flightless. Dorsoventral muscles are wildtype.
The dorsoventral muscles are not affected in mutants. The dorsal longitudinal muscles (DLMs) show severe defects; only 3-5 DLM fibres are present instead of the wild-type six. The fibres are reduced in thickness and appear to be 'wiggly'. There is considerable posterior degeneration of the fibres and defective attachment to the thoracic wall.