In olfactometer tests, adult males and females ofEucelatoriasp. deprived of water were strongly attracted to the odor of okra leaves. Okra leaves from plants subjected to short natural photoperiods (late Oct.–early Nov.) and collected at 0800 h were highly attractive to water-deprived flies. The addition of water to olfactometer cages containing water-deprived flies produced an immediate and striking decrease of 99.4 and 99.9% in the attraction of males and females, respectively, to okra volatiles. Water-deprivedEucelatoriaresponded to the airflow from water-saturated paper, but the response was weaker than the attraction to volatile chemicals from okra.