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A computer-controlled video system for real-time recording of insect flight in three dimensions is described. The flight paths of moths were recorded in a flight tunnel using two CCD cameras placed adjacent to each other at angles of 45 and 135° to the flight tunnel axis and separated by a distance of 120 cm. They were connected to two 28-level gray-scale frame grabbers via two external synchronizers. The two-dimensional coordinates of the flying insect were obtained from the two cameras at 40-ms intervals and transferred to host computer for processing and monitor for real-time display. Due to speed limitation in the image acquisition hardware, construction of the three-dimensional file was carried off-line. The flying insect was rendered as a dark spot in a bright background using a homogeneous light source. As the insect enters into the field of view of the two cameras, the light distribution changes, and the frame grabber detects only those variation in the light distribution which results from a flying insect. The target insect can be as small as 3 pixels and can be tracked in a stereoscopic field of view 60 cm long and 50 cm high. A method was developed that allowed for scalar scoring of various pheromone sources to assess their attractiveness using vector flight parameters. This method was applied successfully for optimization of pheromone blend of the grapevine moth, Lobesia botrana.