The digestive system of P. interpunctella was characterized during its larval development to determination of carbohydrases using disaccharides (sucrose and maltose) and polysaccharides (starch and inulin) as substrate. At 6(th) instar larval, Invertase>alpha-amylase> maltase activities peaks were observed. Invertase was fractionated with acetone and isolated. The Invertase was 485.5 fold purified by Sephacryl S-200 and DEAE-Sephadex. Its kinetic parameters were K(m) of 6.6 mM, V(max) of 0.48, pH optimum of 5.5 and temperature optimum of 30 degrees C. This enzyme was activated by CaCl(2) and inhibited by EDTA. When analyzed by SDS-PAGE it showed one band of M(r) 34 kDa. The understanding of the digestive system of P. interpunctella could be a key step in the design of bioinsecticides.