The baseline premise of this study was that the percentage of bolls susceptible to insect damage decreases as cotton matures and bolls harden, and at some point in the season, further insecticide sprays would not protect enough fruit to offset cost.  Twelve different spray termination points were identified using physiological maturity points in combination with cumulative growing degree days (DD 60s).  Each was placed in a randomized complete block 4-replicate field experiment where individual plants in three, 1-m sections of row were tagged at the uppermost first position white bloom at the appropriate node based on the assigned spray termination treatment.  Lint was hand harvested according to predetermined plant zones.  Treatment lint yields were compared using standard statistical procedures.  Results showed that unacceptable levels of lint loss would have occurred had insecticide sprays been terminated any time prior to NAWF 5, 1127 DD 60s.  The ideal termination point appeared to be NAWF 5 plus the accumulation of 250 additional DD 60s.  Although several weeks remained before actual harvest, there was less than a 2 percent lint advantage to any later insecticide sprays.