Controls wing pigmentation patterning by regulating scale cell development, thereby playing a key role in mimicry and crypsis (PubMed:27251285). Probably acts as an activator of the anaphase promoting complex/cyclosome (APC/C) that promotes the ubiquitin ligase activity and substrate specificity of the APC/C (By similarity). Variations in cort gene cortex directly affect wing pigmentation patterning. Variations affecting cort expression have become a major target for natural selection acting on color and pattern variation in lepidoptera. Belongs to the WD repeat CORT family.