Tebufenozide is the most widely used insecticide for sugarcane borer, Diatraea saccharalis, control in the Louisiana sugarcane industry. Our previous studies indicated a reduction in susceptibility among selected field populations. As part of the resistance monitoring program, sugarcane borers from different field locations across Louisiana were collected in the fall 2004 and spring 2005. The borer response to the chemical was measured using diet incorporation bioassays and median lethal concentrations compared to those of a laboratory strain and previously measured baseline. Significant differences (2- and 3- fold) were measured in LC₅₀ values for one field collected strain and the previously measured baseline. Response of Diatraea saccharalis strains varied between seasons and locations based on LC₅₀ values and development of survivors.