“Powered only by an elastic band, it flits up and down and flaps its wings languidly – just like the swallowtail butterfly it was modelled on. The band powers a mechanical crank that drives the wing motion.

“To our knowledge, our model is the first free-flying replica that has the same basic dimensions, mass and shape as a real insect,” says Hiroto Tanaka of Harvard University’s microrobotics lab, who designed the model with Isao Shimoyama of the University of Tokyo, Japan.”