Mechanisms of boll weevil bait stick (BWACT) activity, including attractiveness relative to traps, competition between traps and bait sticks, and behavior and mortality of weevils responding to the bait stick, were studied in the Lower Rio Grande and Brazos valleys of Texas. Adhesive-coated bait sticks captured two to four times as many weevils as adhesive-coated trap bases; a difference that was not fully explained by the 1.5 fold greater lateral surface area of the bait stick relative to that of the trap base. Overall reductions in trap captures because of competitive interactions with bait sticks were not demonstrated. However, examinations of the temporal patterns of capture suggested that competition from bait sticks may have reduced trap captures during the first 8 to 14 days of trapping, when bait stick pheromone sources were fresh. Weevils responding to bait sticks did not feed or probe the surface of the stick, and when stationary assumed a departure posture with the tip of the abdomen held low and the head held high. Responding weevils contacted the bait stick for an average of 9.4 min, but nearly half remained on the bait stick for less than 5 min. Exposure to the bait stick resulted in 2.2% mortality in 96 h while 3.6% mortality was observed in the unexposed weevils during the same time period. Thus, the bait stick did not supply measurable efficacy against responding weevils.