In particular aspects of the invention, nucleic acid molecules encoding novel proteases identified in the midgut of Diabrotica virgfera virgfera (i.e., western corn rootworm) are provided. The nucleotide sequences encode novel cysteine proteases that belong to the cathepsin L-like subfamily of proteases. Variants and fragments of the nucleotide sequences that encode polypeptide sequences that possess proteolytic activity are further disclosed. Methods of using the nucleic acid sequences that encode novel proteases to protect a plant from an insect pest are provided. Particular embodiments also provide vectors, expression cassettes and transformed host cells comprising a protease nucleic acid of the invention.