We describe a method that permits tracking and quantifying the movement patterns of insects in three dimensions under seminatural conditions. We released individualRhagoletis pomonellaflies onto an apple tree and recorded all movements and behavior of the foraging insect. The type information obtained included: measurement of relative distance flown (net and gross displacement, average distance between stops), relative directness of flight from the fly release point to any point within the tree, relative speed of flight, relative angle and vector information for individual and total displacements, and time spent performing individual behaviors. All these parameters were calculated over the total time the insect spent on the tree and for specific time and spatial windows of particular interest. We also describe a computer program that processes and partially analyzes the gathered data. The usefulness of 3-D analysis is illustrated by providing results that show a trend for reduction in the relative distance flown and for an increase in the directness of flight by flies that searched for and landed on fruit models that released synthetic apple odor compared with models that did not.