Aerodynamics and power consumption of near-hovering lacewings (Chrysoperla nipponensis)

To investigate the flight characteristics and the aerodynamic interactions of a kind of four-winged insect, lacewings (Chrysoperla nipponensis), we experimentally measured the morphological and kinematic parameters in a near-hovering state and numerically calculated the aerodynamic forces and power consumption. It was found that lacewings flap their forewings and hindwings at the same frequency with a constant phase difference (∼30°). Both wings rely on the leading-edge vortex mechanism to produce most of their aerodynamic force during mid-stroke. Comparative analyses of aerodynamic interactions reveal that body motion and contralateral wings have minimal impact on overall aerodynamic performance. However, ipsilateral wings reduce total vertical force by 6%, primarily due to an 18% decrease in hindwing force caused by forewing downwash. Under real-world conditions, hindwings generate approximately 20% less vertical force, leading to a net 6% reduction in total vertical force. All tested specimens satisfied force equilibrium criteria, validating both numerical and experimental approaches. Notably, no kinematic or aerodynamic evidence supports the presence of the clap and fling mechanism. Green lacewings exhibit efficient flight with relatively low power consumption, maintaining near-hovering flight at an energy cost of ∼14 W/kg. The reduced aerodynamic efficiency of the hindwings only slightly increases the total power consumption.