brk^F124 larvae have essentially the same denticle phenotype as brk^M68 larvae, although the residual denticle belts are slightly broader.

Alterations in the pattern of the denticle belts are seen in mutant embryos; the denticle belts often have fewer rows of setae than normal as the anterior rows are absent. Salivary glands are small and remain in the anteriormost position of older embryos due to head defects.

Male escapers have ectopic wing veins. In brk^F124 mutant embryos, small salivary glands are found in the anterior head region. The salivary glands are also not fully invaginated and the invagination appears delayed compared to wild-type. However in the resulting smaller salivary glands a lumen can often be detected indicating that final morphogenesis is unaffected. No evidence for cell death is found. In brk^F124 mutant larvae, the trapezoid form of the abdominal denticle belts is lost and denticle belts appear slightly narrowed in the dorsal ventral extent when compared to wild-type. The anterior row of setae is preferentially missing and a few single scattered setae are formed instead. the loss of setae in the first abdominal denticle rows is more pronounced in the anterior abdominal segments than in the more posterior segments. In the nervous system of brk^F124 mutant embryos, the longitudinal connectives appear thinner and breaks can often be found. Commissures form normally but sometimes have an irregular shape.