Field experiment was carried out to evaluate the effect of four tested pesticides , namely Bio-fly 30x106 Cells/ ml L. and Biogard 6.4% WP as biopesticides , Lannate 90 %SP and Acron 72 % EC as chemical pesticides in reducing the population of the most destructive pests attacking cowpea plant (Cowpea pod borer Etiella zinckenella Tr. , the leafminer liromyza trifolli (Burgess) and the whitefly Bemisia tabaci (Genn.) besides its affect on the number of associated predator Orius albidipennis(Reut.) and the total yield . Data revealed that biopesticides can be used to minimize the pest populations and give a high total yield and did not affect the population of the predator.