The Colorado potato beetle, Leptinotarsa decemlineata (Say) is a very serious pest of potatoes which is highly mobile and capable of rapid evolution of resistance to chemical control. Insect movement, resulting in gene flow between resistant and susceptible populations, is considered to be an important factor affecting the development and spread of insecticide resistance. We investigated the movement of adult Colorado potato beetles by flight and by walking following the treatment with a sublethal dose of imidacloprid in the laboratory. Imidacloprid had a pronounced negative effect on beetle mobility. The proportion of beetles flying and walking, as well as the number and duration of performed flights, were significantly decreased for the treated beetles. Since local selection followed by long-distance dispersal have been reported to lead to serious area-wide problems with the insecticide-resistant Colorado potato beetle, longterm suppression of flight activity recorded in our study suggests that imidacloprid applications may reduce outflow of resistant alleles.