Pheromone traps were reliable for detection and estimation ofEarias insulana (Boisduval) (Lepidoptera: Noctuidae) adult populations in cotton fields. Due to the aggregated distribution in traps, estimates of moth populations were more accurate at low than at high population levels. The relationship betweenE. insulana male catch and larval density could not be assessed because of the numerous chemical treatments applied to the cotton fields. However, when chemical applications were avoided, an increase in male catch was followed by an increase in larval density. SinceE. insulana eggs are difficult to detect and the larvae penetrate the cotton bolls soon after hatching and are therefore hard to control, pheromone traps are particularly useful as a warning device for potential larval infestation.