Tilting motion helps butterflies soar

Butterflies soar by using big wings and slow wingbeats—about 10 beats per second, compared with about 200 in honey bees. A new model shows how they control this jerky, erratic flight: good posture and a bit of waggle. Research on butterfly flight has been limited to studying tethered butterflies in wind tunnels, or simulations focusing only on horizontal motion. In the new study, researchers took high-speed videos of orange oakleaf butterflies free-flying in the lab, and then simulated their unruly flight patterns, along with the intricate air currents they produce. The team found that a body posture perpendicular to the ground helps the insects fly upward, especially when combined with a large rotation of their body timed with each flap of their wings. By toning down this waggle or the angle of their body, butterflies can move forward instead of upward, according to a study to be published in Physical Review Letters E. The researchers say that butterfly flight would make a good model for developing tiny flying vehicles that could be used for surveillance and rescue operations. Frenzied fliers like bees are hard to mimic, but a butterfly’s slower, waggling flight might be more manageable for the rescue robots of the future.