Optomotor regulation of ground velocity in moths during flight to sex pheromone at different heights

Males of two species of moths ( Grapholitha molesta (Busck) and Heliothis virescens (F.)) were flown in a sustained‐flight tunnel in horizontal pheromone plumes. The up‐tunnel velocity of the moths increased with increasing height of flight and for G.molesta was independent of tunnel wind velocities. Use of moving ground patterns verified that the height of flight above the ground was the factor related to the changes in up‐tunnel velocity. Even though up‐tunnel velocity increased with increased flight height, angular velocity of image motion did not. Males appeared to use visual cues from the ground pattern and from other sources to determine their up‐tunnel velocities. The relationship of preferred retinal velocities to optomotor anemotaxis is discussed.