Control of Flight Speed by Minimization of the Apparent Ground Pattern Movement

When a male moth flies towards a chemically alluring female, he determines both the upwind direction and his forward progress from the ground pattern movement beneath him (Kennedy 1940, Heran 1955, Schneider 1965, Kennedy and Marsh 1974, Miller and Roelofs 1978). Thus, the insect completely compensates for its wind-drift, and maintains a constant speed over ground (Marsh et al. 1978). In order to reveal the underlying mechanism by which this information is processed, we measured the flight speed of a moth over a moving ground pattern.