"Flies" is a science fiction short story by Isaac Asimov.
It was first published in the June 1953 issue of Magazine of Fantasy and Science Fiction, and later appeared in Asimov's collections Nightfall and Other Stories (1969).
[1] A group of former college students meet at a reunion twenty years after graduation and discuss their achievements.
One of the ex-students, now an animal behaviorist, is tormented by his ability to read the thoughts of his former friends in their small behavioral tics and gestures.
Unbeknownst to all but the behaviorist, the flies' behavior is caused by their belief that he is Beelzebub.