A Cry1Ab-resistant sugarcane borer (SCB) strain, was selected via F2 screening procedures and confirmed on transgenic Bacillus thuringiensis (Bt) corn plants in Louisiana. Larval survival of Bt-susceptible, heterozygous, and resistant SCB strains was recorded on five non-Bt corn and seven Bt-corn hybrids at two vegetative (V6-V8, V9-V10) and two reproductive (VT-R1, R2-R3) stages, respectively, in 2005 and 2006 in greenhouse tests. Twenty neonates were released on each plant and larval survival was checked 21d after infestation. Larval survival rates of resistant SCB were 14.3%, 9.6%, 24.5% and 18.1% respectively at the four plant growth stages. Regardless of growth stage, survival of the resistant SCB was significantly higher than that of the susceptible and heterozygous SCB on Bt-corn plants. Furthermore, the survival rate of heterozygous SCB was higher than that of the susceptible insect at all developmental stages of Bt-corn plants. No significant differences among the survival rates of the three insect strains were observed on the non-Bt corn hybrids at the V9-V10 stage. However, survival rates of both heterozygous and resistant larvae were higher than that of the susceptible larvae on non-Bt corn hybrids at the other three stages. The results also indicated that the survival rates were low when neonates were infested on the V6-V8 stage Bt-corn plants. During later vegetative stages (>V8), SCB survival rates increased, and may be the result of lower Bt-toxin expression in older plants. Nevertheless, during the reproductive stage (R2-R3), SCB larval survival gain decreased. This effect may be related to the poor nutrition status or hard stalks of those plants rather than Bt-protein expression.