SrpRβ^rK561 mutants have major defects in cuticular development; the larval cuticles are smaller (on average only 40-50% the length of wild-type) and weaker than the cuticles of their wild-type siblings, the mouthparts and filzkorper are poorly formed, and SrpRβ^rK561 mutants frequently have large holes in the dorsal cuticle. In addition, there appears to be a general defect in patterning of the cuticle, with dorsal and ventral structures appearing more lateralized. The ventral cuticle exhibits a loss of denticles and the denticles that are present have a very light pigmentation, more consistent with the pigmentation found in more lateral denticles of wild-type larvae. The dorsal surfaces of the mutant larvae consist of thin hairs and naked cuticle, an arrangement more typical of dorsal-lateral reiogns of wild-type cuticles.