Studies conducted during 1996 through 1998 showed that the use of an at-planting insecticide significantly reduced densities of thrips (adults and immature) compared to the non-treated control. In these studies the use of an at-planting insecticide also resulted in significantly greater lint yield compared to the non-treated. Additional studies were conducted during 1999 and 2000 to determine how thrips infestations impact yield. Thrips densities were lower during 1999 and 2000 compared to those observed during 1996 through 1998. Fewer differences in thrips densities were observed between treated and non-treated plots. Analysis of yield components using plant mapping procedures did not detect any differences between the treated and non-treated plots and there were no significant differences in total yield observed. Results from these studies and previous studies indicate that environmental conditions might influence cotton response to thrips infestations. This interaction warrants further study.