What idiom is the word flying behind?

Idioms with the word "fly" behind them are: the grass grows and the warbler flies, the old swallow flies separately, the stupid bird flies first, Feng Huang Yu Fei and so on.

The grass grows and the warbler flies.

Explanation: oriole: oriole. Describe the scenery of Jiangnan in late spring.

Source: Qiu Chi, Liang of the Southern Dynasties, and the Book: "In late spring and March, the grass grows in the south of the Yangtze River, the peanut trees are mixed, and the warblers fly around." Ding's "Village Residence": "The grass grows in February, and the willows are drunk with spring smoke. The children came back from school early and were busy flying kites in the east wind. "

In this way, flowers and birds sing, grass grows and warblers fly, all of which are the languages of nature. (Zhu Kezhen's Language of Nature)

◎ Combined type; Make attributes and clauses; Describe the scene of spring.