https://www.smithsonianmag.com/smart-news/study-reveals-secr... (2021)

Study mentioned: https://royalsocietypublishing.org/doi/10.1098/rsif.2020.085...

Fantastic study thank you and such evocative language “The fluttery flight of butterflies over a sunny meadow instils fascination, yet the flight of butterflies remains somewhat a mystery. The few flight mechanistic studies performed so far on butterflies have triggered suggestions that they use a variety of unsteady aerodynamic mechanisms for their force production. Among these mechanisms, the upstroke wing clap, first described by Weis-Fogh for insects already in the early 1970s, is one repeatedly reported as used by butterflies. Despite the importance of this mechanism, as far as we know, quantitative measurements of the aerodynamics of the wing clap in freely flying animals are still lacking.”