Partial cDNA of hemolin, an insect immune protein, was cloned from indianmeal moth, Plodia interpunctella, and the rates of hemolin mRNA expression were demonstrated in each stage of development and also by bacterial injections. A deduced amino acid sequence from the cloned hemolin cDNA was approximately $44-54\%$ similar to hemolins of 5 other moths. During development the level of hemolin mRNA was the highest at the time of the larval-pupal matamorphosis. Hemolin was also rapidly induced by the injection of bacteria into the $4^{th};or; the; 5^{th}$ instar larvae. Hemolin induction rate by bacterial challenge was higher in the $5^{th}$ instar larvae than in$4^{th}$ instars. Our results suggest that hemolin could have multiple roles that act both on cellular processes during development and on the immune reactions for the resistance to pathogen invasion.