The effectiveness of 7 insecticides, which included 4 synthetic pyrethroids (NRDC-1614, permethrin, resmethrin and d-phenothrin) and 3 organophosphorous (OP) compounds (fenthion, malathion and naled), was tested against field-collected adult female Culicoides mississippiensis in a laboratory wind tunnel. Knockdown (1 hr posttreatment mortality) and 24-hr mortalities were determined for each compound to indicate relative effectiveness. The pyrethroids were more effective than OP compounds tested. NRDC-161 was the most effective pyrethroid followed by permethrin, resmethrin and d-phenothrin. Of the OP compounds, naled was slightly more effective than malathion, and fenthion was the least effective.