Pink bollworm, Pectinophora gossypiella (Saunders) infestations in upland Gossypium hirsutum L., Deltapine 90 and long staple Pima S-6, G. barbadense L., cotton bolls were initiated at about the same time during the cotton growing season. The upland cotton was planted 11 days earlier than the Pima cotton. Cotton squares (flower buds) of both cotton types were available in mid-May as host material for larval development from eggs laid by overwintering pink bollworm moths. Male moth trap catches in gossyplure-baited Delta traps followed similar trends in both cottons throughout the season, but tended to be higher in Pima S-6 cotton than in Deltapine 90 cotton late in the season. Late crop termination (last irrigation 26 September) as practiced in Pima cotton production vs. earlier crop termination (last irrigation 1 September) as practiced in upland cotton production resulted in higher numbers of late-season immature green bolls, higher numbers of pink bollworm larvae per boll and higher populations of diapause larvae at harvest time in Pima than occurred in the upland cotton cultivar. Pink bollworm seed damage was lower in the Deltapine 90 cultivar than in the Pima S-6 cotton cultivar. Deltapine 90 lint yield was higher than Pima S-6 lint yield.