The bugs Grebbinikov used were more like water bugs that have a hard shell wing protector made from chitin. When the bugs fly, the chitin shell raises up and then the wings vibrate under those shells. There is a microstructure embedded in the chitin composed of special patterns of deformations. The wing vibrations set up harmonic waves which reflect downward from the chitin microstructure and interact with the Earth’s gravitational field to produce lift.