Field tests (1993 - 1996) were conducted in Southwest Oklahoma to determine the uppermost harvestable boll that contribute to yield and develop a termination procedure to accurately predict when to stop insect scouting and insect control in cotton. No cotton was harvested above 4NAWF. Following NAWF procedures based on cotton development measured as plant mainstem nodes above white flower and heat unit (HU) accumulation resulted in the early termination of cotton compared to basing decision on personal opinion. Approximately 1 to 2 insecticide applications can be saved following the NAWF procedure that are applied to protect bolls set above 4NAWF. Production practices and growing conditions will influence the uppermost harvestable boll. Monetary value of bolls indicates that 4NAWF bolls values does not justified the expense of insect control for protection against late-season insects. Termination of fields should occur once cotton reach 5NAWF for irrigated fields plus 350HU and 6NAWF for dryland fields plus 350HU.