What is distinctive about Bartók's 'night music' passages in his string quartets?

Bartók’s ’night music’ style features evocative, atmospheric passages imitating nocturnal nature sounds — insects and birds — appearing prominently in the second and third movements of several quartets. It’s some of the most distinctive nature-writing in 20th-century classical music, where dissonance and stillness evoke the natural world rather than imitate it.