Flies that ‘stick’ upside down landings use different approach than thought

Researchers studying one of the least understood aerobatic maneuvers performed by flying insects, and who call their investigation the “most complete exploration of fly landing maneuvers” to date, report that blue bottle flies that land upside down on ceilings use a more complex series of behaviors than thought. This insight will inform efforts to engineer small robotic fliers to perform similar aerobatics, the authors say, and it can also be applied to the field of neuroscience, where it could lead to new hypotheses for understanding how insect brains function. Although the phenomenon of flies and other insects landing on ceilings is so common as to seem unremarkable to casual observers, the sensorimotor processes underlying this behavior remain mysterious. While previous research has shown that flies may not need to actively adjust their body orientation immediately before touchdown, other observations have suggested that rapid body rotational maneuvers as controlled by sensory processes is critical to inverted landing. Pan Liu et al. used high-speed videography to investigate the landing behaviors of blue bottle flies in a flight chamber, uncovering the geometry of the flies’ body and wing motion through digitized anatomical landmarks. Unlike fruit flies, which barely rotate their bodies before touching down on vertical surfaces, the blue bottle flies used a wide range of rotational maneuvers to land, employing a greater average peak angular rate than those reported for fruit fly and hummingbird escape maneuvers, for example. The flies stuck the landing by swinging their bodies into place with forelegs firmly planted on the surface. The results suggest the flies may use neural processes combined with other sensory cues for inverted landings, meaning small robotic fliers seeking to stick upside-down landings would require integrated computational processes and landing gear to achieve this feat.

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