Homozygous dsf¹ mutant flies do not show an increase in aggressive behavior compared to controls.

dsf¹/Df(2L)cl7 mutant flies do not have significantly different longevity to wild-type flies.

Young mutant males show minimal head-to-head interaction behaviour and almost no homosexual courtship. Mutant males aged individually for approximately 2 weeks and then grouped together show a high level of head-to-head interactions on the first day after being grouped together. By 5 days after being grouped together, the level of head-to-head interaction is barely above the wild-type level, and is significantly lower than the level of head-to-head interaction on the first day after being grouped together. "Swarming" behaviour is seen on the first day that the mutant males are grouped together, with groups of males moving swiftly throughout the test chamber, seeming to chase other mutant males and be chased by them. When the group of moving males encounters an internal boundary (e.g. the surface of the food) the swarm typically does not break up but moves off in another direction. Swarming behaviour persists to day 5 after being grouped together, although the behaviour occurs less frequently than on the first day after being grouped together. Males can show head-to-head interactions during swarming behaviour, although of shorter duration than head-to-head interactions between a pair of males.

Hemizygous dsf¹/Df(2L)cl7 females lack synapses on the circular muscles of the uterus. Homozygous males are substantially delayed in the average time from initiation of courtship until copulation compared to wild-type flies. Homozygous males court males as well as females and males show pairwise and multiple male courtship. Homozygous males have abnormal neuromuscular synapses on ventral abdominal segment A5.

Homozygous females fail to lay eggs voluntarily or under CO₂ anaesthesia. Eggs mature normally in the ovary and pass through the oviducts into the uterus where they degenerate. Homozygous and hemizygous females show significantly longer times from the initiation of courtship until copulation relative to wild-type. This delay results from active resistance by the female, including running about the mating chamber, wing flicking and kicking the male. Females also show resistance during copulation, showing excess activity and actively trying to dislodge males by flicking their wings, bucking and kicking at the males. Homozygous and hemizygous males initiate courtship with mature wild-type virgin females as rapidly as wild-type males, and actively court females, but they show a substantially delayed time to copulation compared to wild-type. The males are defective in abdominal curling, making fewer bends that fall into the maximum degree category (180^o) that is sufficient for copulation. This probably accounts for the increase in time to copulation seen for homozygous and hemizygous males. Homozygous and hemizygous males also actively court both mutant and wild-type mature males even with virgin females present. This includes all courtship behaviours up to and including attempted copulation. Wild-type males do not court homozygous or hemizygous dsf¹ males. No synapses are detected on the circumferential muscles of the uterus in homozygous and hemizygous females, although the innervation of the other genital muscles and segmental abdominal muscles appears normal. The innervation of the ventral abdominal muscles of abdominal segment 5 is abnormal in homozygous and hemizygous males; a few large spherical boutons are present on each fibre rather than strings of small boutons. XX dsf^- tra^- animals show the ventral abdominal muscle innervation phenotype, while their XX dsf⁺ tra^- siblings do not, indicating that dsf acts downstream of tra. XX dsf¹ dsx^D double hemizygotes have wild-type ventral abdominal muscle innervation phenotype, while XY dsf⁺ tra^- dsf¹ dsx^D double hemizygotes have a dsf¹ ventral abdominal muscle innervation phenotype, indicating that dsf acts independently of dsx.