Samples of the air at the tops of cotton plants,Gossypiumspp., treated with long-lasting dispensers containing gossyplure, the sex pheromone of the pink bollworm,Pectinophora gossypiella(Saunders), were pulled through adsorbent cartridges during day and night periods (0600–1800, 1800–0600 hours, respectively) and analyzed by gas chromatography for gossyplure content. The gossyplure was applied (≍1,000 dispensers containing 78 g [AI]/ha) at the pin-square or first flower stage of cotton. Air samples were taken during 3-d periods at approximately 1, 20, 40, and 60 d after treatment. Five Delta traps each baited with 1 mg of gossyplure were used to capture males in each test block. Day and night aerial concentrations of gossyplure in treated cotton fields, with few exceptions, were not significantly different. Average 24-h aerial concentration decreased to 1.4–2.0 ng/m3by day 60, regardless of initial concentration. Catches of male moths in the treated blocks were reduced 99.4–100% compared with controls during 60 d after treatment, indicating that aerial concentrations of ≥1.4 ng/m3of gossyplure generally prevented trap catch. The decreased release of gossyplure from dispensers over time is probably partially compensated for by greater retention of gossyplure in the developing plant canopy.