Downwind migration of the African army worm moth, Spodoptera exempta, studied by mark‐and‐capture and by radar

Abstract. 1. About 166,000 African armyworm moths, Spodoptera exempta (Walk.), were marked at an emergence site near Nairobi when they fed at night on trees baited with dyed molasses. 2. Six marked moths were captured in pheromone traps, including one at 90 km after flying for only one night, and another at 147 km. 3. Moth flight trajectories deduced from radar and from marking showed that migration was downwind. 4. During migration, moths become dispersed; hence the high densities that lead to outbreaks must be produced by concentration. 5. Some moths were ready to mate on the same night they completed their long‐distance flight.