The present study was conducted at Sakha Agricultural Research Station during 1994 and 1995 cotton seasons. The relationship be‌tween cotton leafworm and bollworms population and field infestations was investigated. Adult populations of Spodoptera littoralis, Pectinopho‌ra gossypiella and Earias insulana were more attracted to pheromone traps than to light traps. From the total catch, pheromone baited traps attracted 76.38, 78.74 and 93.46, respectively, in 1994. On the sec‌ond season 1995 they attracted 76.39, 88.12 and 61.98% of adults of the three pests, respectively. Also, they better detect pest population particularly early in the growing season. A week correlation between S.Iittoralis adult catch and egg deposition were computed in spite of high adult catch by both types of traps. Bollworms adult population progressively increased toward fate summer and early fall and then declined, but field infestation consistent‌ly increased due to cumulation of larvae. Correlation coefficient values (r) between % infestation and trapped adults of P.gossypiella by light and pheromone traps were 0.41 and 0.91 in the first season. Similar trend was noticed during the second one for light-trapped adults, but not for the pheromone trapped ones. The correlation values between % infestation of E.insulana and number of trapped adults were higher in pheromone traps than light traps. In conclusion, as number of field adults fluctuates and pest de‌pends on many factors, direct examination of cotton fields is a must to detect population changes, consquently timing of insecticide application, if any is required.