none The behavioral response of female Apanteles kariyai Watanabe (Hymenoptera, Braconidae) to the volatiles of plant species, both food plants and non-food plants of the host larvae, Pseudaletia separata Walker (Lepidoptera: Noctuidae) was tested in a Y-tube olfactometer. When uninfested leaves of corn (Zea mays L.) or rice (Oryza sativa L.), which were the food plant species of the host larvae vs. clean air were offered in the Y-tube olfactometer, A. kariyai significantly preferred the leaf odor to clean air. However, the wasps also significantly preferred the odor of plant species which cannot be the host's food plant, such as mulberry (Morus bombycis Koidz.), dandelion (Taraxacum japonicum Koidz.), Welsh onion (Allium fistulosum L.) and kidney bean (Phaselous vulgaris L.), to clean air in the olfactometer. From headspace analysis of uninfested detached corn leaf volatiles, (Z)-3-hexenol and (Z)-3-hexenyl acetate were identified as the main compounds and of these two compounds, only (Z)-3-hexenol attracted A. kariyai .