Fig. 2. Full range of variation in the responses of P. americana males as they tracked a pheromone plume in zero wind after being pre-exposed to (A) wind + pheromone, (B) no wind + no pheromone and (C) wind only in the Series 2 experiments. Controls tracked plumes while being exposed to wind and pheromone continuously (D). Black circle in center of plots represents the point of release of the cockroaches. Cockroach tracks on each experimental day are denoted by a different color. Wind direction was from left to right prior to cessation, and the pheromone source was on the left-hand edge of the arena (the arena is depicted by the black boxes in which the tracks are plotted). Mean tracking times (and s.d.) are given.