n. any of various flies, that bite or annoy livestock and other animals; irritating person
Like a gadfly, he irritated all the guests at the hotel; within forty-eight hours, everyone regarded him as an annoying busybody.
Sentence in Classic:
They fled to the other end of the court like a herd of cattle maddened by the gadfly in early summer when the days are at their longest.
The wind, that seemed to blow as they drove, dropped when the carriage stood still; gadflies settled on the steaming horses that angrily shook them off.
Anna Karenina(V2) By Leo Tolstoy Context