This article presents the activity of carbohydratases and proteases in the midgut of Cameraria ohridella larvae--an oligophagous pest whose preferred feeding is horse chestnuts leaves. Optimal media pH of the assayed enzymes were similar to those of other Lepidopterans. Relatively high amylase activity, as well as maltase and sucrase activities, indicates that starch and sucrose are the main digested saccharides. Trehalase activity was similar to that described in other Lepidopterans. Activities of glycosidases were significantly lower than those of disaccharidases what suggests that neither cellulose nor glycosides are important for C. ohridella. Trypsin is the main endoprotease of this pest. Like in other leaf-eaters carboxypeptidase activity was higher than that of aminopeptidase. The activity of the majority of examined enzymes increased in the following successive pest generations, which could be explained by the decreased nutritional value of older leaves. Probably this phenomenon in hydrolases activity in Cameraria is a nonspecific mechanism present at this stage of co-evolution of the horse chestnut and its pest.