A Roundabout for Studying Sustained Flight of Locusts

Abstract

The purpose of the technique described here was to study the influence of external factors upon the flying speed and the ability of small ‘swarms’ of locusts to sustain prolonged flight. The wind forces acting on a flying animal depend only on the motion of its elements relative to the air mass, i.e. on the relative wind. Instead of investigating actual free flight, a locust can therefore be suspended in front of a wind tunnel and made to fly against a streamlined and uniform current of air, the wind speed being adjusted so as to correspond to the air speed of the freely flying insect. Under such conditions it has been possible to make a single individual fly for several hours. But a very large tunnel would be necessary for a number of animals to fly simultaneously as is required for quantitative work. Instead of moving the air mass, one can move the suspended animal through still air with a speed corresponding to the flying speed and so have several insects flying at once. Thus proper aerodynamic conditions for flight can be obtained by attaching the animals to a revolving ring, provided the ring is made so large that the angular velocity is kept small.