Figure 2.

Active and passive stabilization of fruit fly flight. (a) Fruit flies use fast gyroscopic sensors called halteres to mediate flight control. Each haltere vibrates during flight and detects changes in body orientation. If glued down, the haltere no longer properly functions. (b) Dandelion seed fibres add drag to the insect body, thus increasing passive stability. (c) Inset: body orientation and flight trajectory of a fly with halteres disabled (left), showing a tumbling motion while falling downwards. When fibres are attached to a haltere-disabled insect, it is able to keep upright as it descends (right). Main figure: insects are released in air, and flight performance is assessed by measuring the trajectory angle with respect to the downward vertical. Distributions of flight angles for insects with halteres disabled (light grey) and insects with halteres disabled and with fibres attached (dark grey). (Online version in colour.)