Temperature-sensitive period extends from shortly before puparium formation into early metamorphosis. Heat induced expression during this period irreversibly abolishes male behaviour. Heat induced expression in X/X tra¹/tra¹ tra^hs.PBa and X/Y tra¹/tra¹ tra^hs.PBa mutants during the temperature-sensitive period abolishes male behaviour. These mutants exhibit a female body (except for the CNS) and have a female pheromone pattern. They show indiscriminate mating behaviour, suggesting they are unable to discriminate among their sexual partners (these 'females' will mate with M.domestica males). X/X tra¹/tra¹ tra^hs.PBa females are fertile. Heat induced expression during the temperature-sensitive period abolishes male behaviour and allows partial recovery of female behaviour in the X/X mutants, the X/Y mutants show some female behaviour. Heat induced expression before and after, but not during, the temperature-sensitive period in X/X mutants does not abolish male behaviour. Irrespective of the heat-shock regimen all flies have a female pattern of pheromones. By introducing dsx^D, X/X and X/Y flies now have a male body and male pheromone pattern, these flies are unattractive to males but will still court both sexes.

XX tra^-/tra^- flies carrying tra^hs.PB develop as morphologically normal females, but they do not lay eggs.