Melon fruit fly, Bactrocera cucurbitae (Coquillett) is an important pest of cucurbit crops that can cause severe damage to its host species and thus reduce drastically the crop production. Use of digestive serine proteinases by dipterans has led to the present investigation in which the influence of partially purified chick pea proteinase inhibitors on the survival and digestive processes of melon fruit fly was determined. The artificial diet bioassay using various concentrations (viz. 12.5, 25, 50, 100, 200 and 400µg/ml) of the partially purified chick pea inhibitor on the second instar (64-72old) larvae revealed that the larval weight gain and mean larval growth rate were significantly inhibited (p<0.01) while the food assimilated by the larvae varied with treatment. Enzymatic assays at different concentrations (50, 100, 200 and 400µg/ml) of partially purified chick pea PI significantly reduced the activities of digestive enzymes (trypsin, chymotrypsin and elastase) and significantly induced the activities of other enzymes viz. esterases, acid and alkaline phosphatases, glutathione-S-transferases and catalase.