The domesticated silkworm is an economically important insect that is widely used as a lepidopteran insect model. Although somatic sex determination in the silkworm is well characterized, germline sex determination is not. Here, we used the transgenic-based CRISPR/Cas9 genome editing system to study the function of the gene in . is the homolog of a factor important in germline sex determination in . mutants had abnormally shaped eggs that were disordered in the ovarioles, and gonad development was abnormal. Interestingly, wing discs and wings did not develop properly, and most of the mutants failed to eclose. Gene expression analyses by qRT-PCR showed that gene was highly expressed in the wing disc and epidermis. Genes involved in the WNT signaling pathway and wing development genes and were downregulated in the mutants when compared with wild-type animals. These results demonstrate that the gene product plays an important role in wing metamorphosis. Thus, this study provides new insights into the multiple functions of beyond germline sex determination.