The Cry23Aa/Cry37Aa proteins from (Bt) have been described toxic to larvae. In general, it is believed that Cry23Aa and Cry37Aa act jointly to exert the insecticidal activity, while there is no evidence of their toxicity individually. Therefore, in the present study, the contribution of each protein in the insecticidal activity toward larvae has been assessed. The results showed that both proteins were toxic for larvae when tested individually. Contrary to what was claimed previously, our results suggest that the presence of both proteins is not necessary to exert toxicity against larvae. Also, the binding behavior of Cry23Aa protein to midgut receptors of larvae has been determined. According to our results, Cry23Aa binds to brush border membrane vesicles (BBMV) specifically and independently of Cry37Aa. Due to the lack of common binding sites, Cry23Aa can be pyramided with Cry3Aa protein for better management of .