"Mayfly shaking a tree" literally means an ant trying to shake a big tree, symbolizing an extremely small force attempting to shake something powerful. This idiom comes from Han Yu's poem "Tiao Zhang Ji" in the Tang Dynasty: "An ant tries to shake a big tree, laughably overestimating itself." Its deeper meaning lies in satirizing those who overestimate their abilities and bite off more than they can chew, often used to describe ineffective challenges against powerful forces or solid things. It is mostly used in a derogatory sense, carrying a tone of mockery and contempt, emphasizing the vast disparity in strength and the challenger's behavior being doomed to fail and laughable. In cultural context, it reflects the wisdom of "acting according to one's ability" in traditional Chinese culture and opposes blind arrogance. For example, when someone tries to challenge authority or a powerful opponent, others might use this idiom to evaluate their behavior. It should be noted that this idiom is usually used for third-party evaluation and is not suitable to say directly to the challenger, lest it appear too harsh.
📝 Example
As a newcomer who had just entered the industry, he wanted to challenge the company president's decision—simply like an ant trying to shake a tree. (A metaphor for overestimating one's own strength in an attempt to shake something far more powerful, with a mocking tone.)
Facing the world champion, this amateur player's challenge was no different from an ant trying to shake a tree—there was no chance of winning. (Describing an act of overestimating one's abilities, doomed to fail.)