Gossyplure-baited trap studies were conducted from 1981 to 1988 in the Imperial Valley, California, to define the seasonal distribution, seasonal and between-season variation in pink bollworm, Pectinophora gossypiella (Saunders), populations and the effect of several variables that affect trap catches. The results showed that early-season catches reflected the magnitude of emergence from overwintering populations. The data were useful in identifying fields and areas that had a high probability of developing economic infestations during the season. Temperature had a significant impact on trap catches. Also, yearly rates of population increase as measured by moth trap catches were similar during the study period.