The present invention is related to modified, synthetic DNA sequences allowing improved insect control due to their improved mRNA procession, stability and their enhanced translation in higher plants. Said synthetic DNA sequences comprise useful tools for resisitance management, especially for overcoming cross-resistance problems. The improvements are achieved by providing synthetic modifications of the truncated DNA sequence (SEQ ID NO:3:) of the cry9Aa gene, preferably SEQ ID NO:2: coding for a protein characterized by having an amino acid sequence SEQ ID NO:1: or alterations thereof still having substantially the same insecticidal action as the insecticidal protein encoded by the cry9Aa gene of Bacillus thuringiensis ssp. galleria (Btg). Also disclosed is the use of the modified, synthetic DNA sequences for producing said insecticidal protein and for producing transgenic plants expressing effective amounts of the insecticidal proteins.