gadfly
gad.fly \'gad-.fli-\ n 1: any of various flies (as a horsefly, botfly, or warble fly) that bite or annoy livestock 2: a person who annoys or stirs up from lethargy
Webster's English Dictionarygad.fly \'gad-.fli-\ n 1: any of various flies (as a horsefly, botfly, or warble fly) that bite or annoy livestock 2: a person who annoys or stirs up from lethargy