Sexual pheromone traps were used in cotton fields to estimate the population of pink bollworm, Pectinophora gossypiella (Saunders) moths at Behira Governorate during 1999 and 2000 seasons. Relation­ship between early spring trapping of the pest and its population during the cotton season was studied. Moths emerged from diapaused larvae in spring could be used as a monitor of size and population of pink boll­worm at the beginning of the season during cotton flowering. Number of pink bollworm moths caught in pheromone traps during cotton flowering was highly significant positively correlated with the number of moths caught during boll formation. There was an insignificant negative correlation between number of P. gossypiella and Earias insulana larvae inside green boils in cotton fields, 1999 and 2000 seasons. Accordingly, when the inside number of pink bollworm larvae increased, the number of spiny bollworm larvae de­creased. Also, an insignificant positive correlation between average num­ber of pink bollworm in 100 green cotton bolls at the end of the two studied seasons and average number of moths emerged from diapaused larvae in the following spring.