The banana weevil Cosmopolites sordidus (Germar) (Ceoloptera: Curculionidae) is native to Malaysia and Indonesia but is found in nearly all banana-growing areas in Guam and other Micronesian islands. Injury is caused by grubs (larvae), which tunnel through the corms. Extensive feeding damage by grubs results in root destruction, slowed plant growth, reduced fruit production, and, sometimes, toppled plants. The tunneling by the grubs makes the corms susceptible to invasion by secondary decay organisms. Pheromones traps have been used in various countries to monitor this pest population. In Guam, we have carried out pheromone trapping studies on the monitoring of the population level of C. sordidus. Each Ramp Trap loaded with pheromone lure was set up at 10 locations in the island in November, 2005. Weekly counts were made on the number of weevils caught by the pheromone traps. The data indicated that higher population level (>10/week) was recorded in the northern region while low (<5 weevils/week) to medium level (5-10 weevils/week) population was in the southern parts of the island. Ground traps baited with pheromone lures caught more adults than the alternative trap and were seen to be superior to ramp traps baited with identical compounds.