Studies were conducted at the Macon Ridge and Northeast Research Stations to determine the effectiveness of two Bacillus thuringiensis (Bt) insecticides (Condor OF and Dipel ES) in controlling the bollworm and tobacco budworm (BW-TBW) complex. Results of bioassays using Condor OF on the LSU colony of TBW indicated that rates of Condor OF ò 16 oz (form)/acre and Larvin 3.2 F (16 oz [form]/acre) produced mortality significantly higher than the untreated control at 2 h posttreatment. Rates of Condor OF ò 8 oz (form)/acre and Larvin 3.2 F (16 oz [form]/acre) produced mortality significantly higher than the untreated control at 72 h posttreatment. Results of bioassays using Dipel ES on a field collected TBW strain indicated that rates of Dipel ES ò 8 oz (form)/acre and Larvin 3.2 F (16 oz [form]/acre) produced mortality significantly higher than the untreated control at 2 h posttreatment. Only Dipel ES at 64 oz (form)/acre and Larvin 3.2 F (16 oz [form]/acre) produced mortality significantly higher than the untreated control at 72 h posttreatment. Regardless of TBW strain or Bt (Condor OF and Dipel ES), mortality levels did not dramatically increase as dosage rates increased, indicating a relatively flat dosage response line. LSU colony larvae exposed to a single application of Dipel ES at 4 oz (form)/acre required significantly longer to pupate (ca. 2 d) than unexposed larvae. There were no significant effects of this treatment on pupal weight or days from pupation to adult eclosion. Field studies with increasing rates of Condor OF indicated that rates ò 16 oz (form)/acre and Larvin 3.2 F (16 oz [form]/acre) significantly reduced square damage below that of the untreated control. BW-TBW square damage in plots treated with Condor OF at 4 or 8 oz (form)/acre was not significantly different from the untreated plots.