The decision to terminate insecticide treatments at the end of the growing season is one of the most perplexing management decisions that cotton growers and their consultants face. Recently research data has shown the level of boll maturity required for bolls to be safe from injury by boll weevil and bollworm/tobacco budworm. This maturity is measured in heat units (HUs) accumulated on a daily basis. Knowledge of boll maturity and susceptibility to insect injury, combined with recent advances in plant monitoring have made it possible to identify the last harvestable boll population and thus determine when it is safe to terminate insecticide treatments.