This article describes a case of intestinal myiasis--the presence of fly larvae in the intestines--in a 12-month-old baby. The asymptomatic child was twice treated by her physician for a presumptive diagnosis of pinworm infection. The mother continued to see "worms" in the child's stool and brought her to a public health primary care clinic where she was evaluated by nurse practitioners. Larvae (maggots) of the false stable fly, Muscina stabulans, were identified in each of two stool specimens collected on different days. Examination of stool specimens from other family members showed no larvae. The likely source of the child's infection was over-ripened bananas, which were kept in a hanging basket. No pharmacologic treatment was prescribed, but the parents were instructed to cover the fruit and wash it before consumption. Nurse practitioners are encouraged to report suspected cases of myiasis and to work with patients, their families and public health personnel in order to confirm the diagnosis, identify the source and make suggestions to prevent further infestation.