To evaluate the field feasibility and agronomic efficiency of the mixture of the sexual pheromone (Grandlure) - 0.8%, mixed with cypermethrin - 6.4% (experimental compound Sirene BW), for the control of the boll weevil (Anthonomus grandis, Boh.), two tests were conducted at different locations in Paraná state (Brazil), during the 1994-95 cotton season. Application of Sirene BW was made with the help of a pistol, so that each pull on the trigger released a standard drop placed on the top leaves of a cotton plant. The drops had high viscosity, resembling a grease. The plots measured ca. 3.5-4.0 ha. On the central area of the plots, the drops were distributed 8 m apart from each other, and only 4 m apart on the borders (30 m around all the plot). The mixture was applied three times, with 10-14 day intervals. The first application was made 31-32 days after seed emergence and before square setting time. Plots with similar management practices were conducted for comparison purposes, where insecticides for boll weevil control were applied following official IPM recommendations. Evaluation of the treatments was made weekly, randomly choosing 12 locations measuring 400 m2, assessing 25 squares/location and counting the number of bolls damaged either by feeding or oviposition. Results demonstrated that the mixture of pheromone and cypermethrin can efficiently control the pest up to 80 days after seed emergence. This treatment provided improved protection to the boll structure present on the lower half of the canopy, resulting in higher crop yield when compared to plots where the pest was exclusively controlled by insecticides. Application of Sirene BW near overwintering refugia sites delayed the spread of the boll weevil on the entire cotton field.