Biological control of aphids using "banker-plants with the parasitoiid, Aphidius colemani Viereck (BPAC)" was carried out on cucumber in greenhouse. The BPAC consisting of barley seedlings infested with Schizaphis graminum (Rondani) enhanced the early establishment of Aphidius colemani in the greenhouse and prolonged the control of Aphis gossypii on May 8, 2001. The BPAC was placed in the greenhouse at transplanting at the rate of 1 per 30 m2 of cucumber. Although good control effect was gained until early August after placing banker plants on May 9, the effect after then because of high temperature. The aphid population on cucumber in control plots reached to a peak on June 26, and decreased because of entomopathogenic fungus for rainy season of July, and increased again to a very high population on August. Animals and man; Control; Biological control; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Habitat Aphidius colemani (Aphidiidae); Control of; Aphis gossypii (Hemiptera); Control using 'banker plant' system in greenhouses, evaluation; Hemipteran hosts; Aphis gossypii Aphis gossypii (Aphidoidea); Control by; Aphidius colemani (Hymenoptera); Control using 'banker plant' system in greenhouses, evaluation; Hymenopteran parasites; Aphidius colemani; Man made habitat; Greenhouses none