Homozygotes show a slight drooping of the wings and the indirect flight muscles (dorsal longitudinal and dorsoventral muscles) degenerate to various degrees. A splitting and degeneration of myofibrils is seen in some regions, but in others the myofibrils appear completely normal. Homozygotes with expanded wings generally have weak flight ability, while those homozygotes with normal wings are have weak or moderate flight ability. Homozygotes have significantly reduced viability.