not hurt a fly
(redirected from couldn't hurt a fly)not hurt a fly
To harm nothing or no one. Said of one who is particularly gentle, shy, diffident, or timid by nature. My brother is a very sweet, warm-hearted man who wouldn't hurt a fly. How can you suspect him of committing this crime?
not hurt a fly
Also, not hurt a flea. Not cause harm to anyone, be gentle and mild, as in Paul's the kindest man-he wouldn't hurt a flea, or Bert has a temper but it's all talk; he wouldn't hurt a fly. Both fly and flea are used in the sense of "a small insignificant animal." [Early 1800s]
wouldn't hurt a fly
orwouldn't harm a fly
If someone wouldn't hurt a fly or wouldn't harm a fly, they are very kind and gentle. She was such a lovely girl, who wouldn't have hurt a fly. He is, he insists, a pacifist, who would not harm a fly.