Odor-guided flight in moths

Floor Patterns

These images show four sequential flights of the same male moth to the same pheromone source, in the same wind speed, over four different floor patterns. (As with previous tracks the moth's position is marked each 1/30 s, and the wind is blowing from right to left). In all of these images the time averaged envelope of the pheromone plume is represented by gray shading.

Image 1, above, is the flight track of the moth over the standard pseudo-random pattern of dark dots on a light background. Dots have been chosen because the dark-light transition at their edges has no preferred orientation.

Image 2, above, is the flight track of the moth over transverse stripes the same width as the dots in panel 1. In this pattern the dark-light edges are all oriented perpendicular to the wind direction. Thus, when the moth crosses one of these edges as it flies upwind it gets very strong front-to-back visual flow, but very little side-to-side flow (since it rarely crosses a dark-light edge from the side). The result is that the moth can control it's speed toward the source very well, but because the visual information on it's sideways movement is poor it slides much further across the wind than when flying over the edge-rich dot pattern.

Image 3 is the flight track of the same moth flying over stripes oriented in parallel with the wind direction. In this case the moth crosses the dark-light edges only when moving across the wind. Thus it gets very good visual information that it is moving sideways, but very poor visual information about it's speed with respect to the wind. The result is that the zigzag flight track of the moth is much narrower over the longitudinal stripes, but he flies faster than when he is flying over the dot pattern.

Finally, Image 4 is the flight track of the moth over a checkerboard pattern that combines elements of the longitudinal and transverse stripes. The result is a flight track very similar to the moth's performance over the dot pattern. This is because the moth is crossing many dark-light edges as it moves side-to-side and forward, thus receiving high quality visual information about it's movements.

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