Аннотация:The flight of the smallest insects is of special interest for general biology, biomechanics and aerodynamics, but until recently it was barely researched. It has been shown that the smallest insects are capable of active flight, but for many microinsects it is not known how fast they fly especially compared to larger related species. Ptiliidae and other Staphylinoidea present a convenient range of related species with high variety of body size for this task. We recorded flight of 17 species of Ptiliidae, Staphylinidae and Silphidae by two synchronized high-speed cameras.The beetles were flying in spacious transparent boxes. It allowed beetles to maneuver freely and reach the maximum possible speed. Infrared LED lighting, invisible for insects, made it possible to achieve the necessary exposure for highspeed recording and keep the light level close to natural for beetles. The flight trajectories were reconstructed frame by frame and triangulated. After smoothing, the speeds and accelerations were calculated. Ptiliids, like the other studied beetles, show continuous maneuverable flight with complex trajectories. The average flight speed is from 5 to 44 cm/s, depending on the species, the maximum speed is up to 98 cm/s; the beetles are capable ofaccelerating up to 2.4 g. These measurements indicate the ability of active migration in the absence of wind. We have performed regression analysis of speed and acceleration on body length and shown that among staphylinoids with membranous wings speeds and accelerations allometrically increase with increasing body size, but ptiliids fall out of the trend: their flight characteristics are higher than in the other studied beetles of comparable size. Unlike miniature hymenopterans, thrips and dipterans, flight mechanics of miniature coleopterans have not been studied. To find out what adaptations determine flight performance of Ptiliidae we performed macro high-speedvideo recording and 3D reconstruction of morphology and kinematics in Paratuposa placentis and explored its flight aerodynamics by using new high precision numerical simulation method with a resolution down to individual setae. Wingbeat cycle of P. placentis and other Ptiliidae is unique to insects. The wings follow a pronounced figure-of-eight loop that consists of subperpendicular up and down strokes followed by claps at stroke reversals above and below the body. The elytra act as inertial brakes, halving the excessive body pitch oscillation. Computational analyses suggest functional decomposition of the wingbeat cycle into two power half strokes, which produce a large upward force, and two down-dragging recovery half strokes. In contrast to membranous wings of the same size, bristled wings produce slightly smaller aerodynamic force due to air permeability. But the motion of light bristled wings requires much less inertial power that significantly reduces cycle-averaged and peak power consumption. Muscle mechanical power requirements thus remain positive throughout the wingbeat cycle, making elastic energy storage obsolete. These adaptations explain how Ptiliidae and other miniature insects could preserve good aerial performance during miniaturization.This study was supported by the Russian Science Foundation (project number 22-14-00028), Russian Foundation for Basic Research (project no. 18-34-20063), JSPS KAKENHI (grant numbers 18K13693 and 19H02060), Deutsche Forschungsgemeinschaft (project numbers LE905/16-1 and LE905/18-1).