Homozygotes have a weak drooping or held-out wing phenotype. The dorsal longitudinal muscles (DLMs) show many defects, including improper splitting, variation in fibre number and degeneration (degeneration occurs a few hours before eclosion). The dorsoventral muscles (DVMs) are usually normal, but degeneration is seen in a few flies. An aberrant splitting is seen along the length of the myofibrils. Homozygotes with expanded wings have weak or moderate flight ability, while most of those homozygotes with normal wings are have moderate flight ability.