Abstract The partial success of applications of dieldrin, deltamethrin and endosulfan for tsetse control in also reducing populations of Simulium spp. in a riverine Guinea savanna habitat in Upper Volta has been established. However, there is insufficient information available concerning the resting sites of adult Simulium to determine the best location of spray swaths to achieve the maximum effect. Further trials based on knowledge of the biology of adult Simulium could improve the success of the technique for blackfly control. It is suggested that localised adulticiding in onchocerciasis control schemes could be effective, particularly where a high level of reinvasion causes unacceptable levels of disease transmission for short periods of the year.