To find some antibacterial peptides responsible for bacteria resistance, we performed differential hybridization with two types of [á-32P]dCTP-labeled total cDNA probes synthesized from normal and immunized larvae. Thirteen individual cDNA transcripts were expressed differentially in a total 1,862 random cDNA clones. To confirm that the selected two cDNA clones are differentially expressed in immunized larvae with E.coli. Northern blot analysis was carried out at 0, 4, 8, 16, and 24 hrs after E.coli injection The mRNA transcript of functionally unidentified gene(clone no. SC1) was up regulated after 4 hrs and began to remarkably increase the expression after 8 hrs after E. coli injection. The expression of the Copris tripartitus HSP 70 gene (clone no. SC2) was up regulated after four hrs, reaching the highest point level after 8 hrs and then declined gradually after 16 hrs.