Odor-guided flight in moths

Perceived Visual Flow

These three images are maps of the direction of visual flow field movement across the downward-facing half of an insect's visual field (what it sees through the bottom half of its compound eyes where its eyes are pointing) as it flies flat above the ground. The length of the arrows represents the amount of image flow at each position as viewed by the insect.

1. Straight and level forward flight (flow fields indicate the world is moving by underneath you directly from front to back-since you're moving and the world isn't, this means you're flying straight forward).
2. Turning in place while hovering (flow fields indicate that the world is moving in a circle around you with less movement directly below you).
3. Figure C has two possible interpretations, either the insect is side-slipping through still air or it is flying forward straight and level and being drifted to the right at a 45 degree angle by a wind from the left. Information that the insect has about its intended flight direction and other environmental cues will allow it to discriminate between these two possibilities (after David, 1986).

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