Simple pheromone traps were assessed to identify a suitable trap for use in Tanzania to monitor population size and subsequently forecast outbreaks ofHeliothis armigera.The Ukiriguru trap was found to be satisfactory and was therefore adopted. The efficiency of the Ukiriguru pheromone trap relative to a Robinson light trap in monitoring the activity ofH. armigerawas also assessed over a three year period. Overall, although the light trap caught a proportionately higher number of moths, there was evidence that the pheromone trap could be used reliably to monitor the activity of this insect in Tanzania until a more suitable trap is identified. The relationship between the number of moths caught in the pheromone and light traps was studied. Although the number of females and males caught at the light trap at peak catch were in phase in two out of the three years of study, there was no relationship between the ratio of males to females with the size of female catch. The relationship between the number of moths caught at the pheromone trap and moths caught at the light trap was variable. Similarly, the ratio of males caught in the pheromone trap to the number of females caught in the light trap with the size of the female catch in the light trap was also variable. Thus, further studies on the sexual structure of moth catches at the pheromone and light traps is needed to increase the understanding of how these traps function.