A mutant strain of the silkworm Bombyx mori (L.) (Lepidoptera: Bombycidae) was proposed as a model for Parkinson’s disease. Homozygous op mutants exhibiting translucent larval integument are reported to exhibit occasional unique actions such as vibration. This study investigates the validity of a previous report on this abnormal behavior and movement of mutant and its suitability as a model for Parkinson’s disease. A previously reported study movie documenting occasional unique actions of op/op larvae was considered; it revealed that these actions were simply reactions to the touch of other larvae. Moreover, xanthine oxidase injection did not rescue the phenotype of op mutant larvae, bringing into question the proposed role of the uric acid synthesis-modulating pathway in this mutant.