Abstract. Laboratory and field trials were conducted to determine the action of bendiocarb against triatomine vectors of Trypanosoma cruzi. Bendiocarb concentrations of 100 mg active ingredients/m2 killed all exposed triatomines; at lower concentrations Triatoma infestans was the most susceptible, followed by Rhodnius prolixus and Panstrongylus megistus. The ovicidal effect of bendiocarb was slight. Residual activity of bendiocarb applied to earthen walls ("barro") was depleted by % within 2 months postspray and virtually nil 4 months after application. Field trials in an endemic area of Brazil where P. megistus is the sole domestic triatomine demonstrated that bendiocarb is effective in reducing triatomine densities. Household infestation rates were reduced from 18% prespray to 7% postspray. Panstrongylus megistus density was reduced from 7 per man-h prespray to 1.5 per man-h postspray. The practical use of bendiocarb in large-scale campaigns for the control of Chagas' disease will depend on cost.