I examined the flight behavior of the Mexican bean beetle,Epilachna varivestisMulsant, at 2 types of simulated patch boundaries, and compared such behavior with the assumption of random movement often incorporated into simple diffusion models. I also examined flight behavior from the patch edge with respect to wind direction and sex. Movement from the patch edge was found to be equally nonrandom for both boundary types, with =2/3 of the beetles flyingin the direction of the host plants. Beetles also displayed a tendency to fly upwind or perpendicular to the wind at low wind speeds and downwind at high wind speeds. Flight behavior was not affected by sex of the beetles. Because observed flight preference did not vary between patch boundary types or between sexes, nonrandom movement from the patch boundary could likely be incorporated into diffusion models without significantly increasing their degree of complexity.