As troublesome as a wasp in one's ear. [ Proverb ]

She is as quiet as a wasp in one's ear. [ Proverb ]

Attack not thoughtlessly a wasp's nest, but if you do, stand fast. [ M. Claudius ]

Example is a hazardous lure: where the wasp gets through, the gnat sticks. [ La Fontaine ]

Calumny is like the wasp which worries you, and which it is not best to try to get rid of unless you are sure of slaying it; for otherwise it returns to the charge more furious than ever. [ Chamfort ]