Diseases caused by beetle larvae infestation are known as intestinal canthariasis. Canthariasis from the cigarette beetle, Lasioderma serricorne, is quite rare; however, with the accumulation of genetic references, such cases of accidental pseudo-parasitism have been increasingly recognized. Here, we describe a case of asymptomatic gastrointestinal passage of L. serricorne in a 4-year-old male. Larval identification was conducted by PCR-sequencing targeting cytochrome c oxidase subunit 1 using DNA extracted from the larvae. Due to the difficulty of differential identification of beetles using larval morphology, DNA barcoding is essential.