Nucleic acid sequences and insecticidal proteins encoded from these sequences are provided. Insecticidal proteins encoded by large operons situated within the primary sequence of large extrachromosomal plasmids present in Bacillus thuringiensis are disclosed. Methods for making transgenic plants resistant to insect infestation as a result of expression of one or more of these proteins is disclosed. Bacillus thuringiensis strains exhibiting broad host range insecticidal specificity are also disclosed.