A 75-year-old man with type 2 diabetes and a history of previous empyema surgery was admitted to our hospital due to difficulty moving caused by chronic obstructive pulmonary disease and dehydration. During the first two days of hospitalization, intestinal myiasis was diagnosed after maggots were found in his diapers. After the maggots disappeared, he developed a fever, prompting antibiotic therapy for a suspected secondary infection, resulting in clinical improvement. Despite thorough home cleaning, no flies or maggots were found, and the source of infection and the fly species remained unknown. Recent reports suggest a higher prevalence of myiasis among the elderly, even with overall improvement in hygiene. While myiasis is typically mild, it is a condition that requires consideration in an aging society. Myiasis is a disease that should be considered in the differential diagnosis of the elderly, especially in people who are bedridden or frail.