Abstract  [Aim]  The diamondback moth, Plutella xylostella (L.) has developed high levels of resistance to several insecticides. The aim of this study was to identify a novel compound to control the diamondback moth.  [Methods]  We carried out a series of laboratory and field studies to investigate the behavioral effects of crude extract and three terpene compounds from the invasive weed Tithonia diversifolia on the diamondback moth. Crude extracts of T. diversifolia were processed in the laboratory using four different solvents, and the active compounds were identified through gas chromatography coupled with mass spectrometry. Y-tube olfactory assays were performed to evaluate the behavioral responses of unmated female diamondback moth to the crude extract and the three terpene compounds. [Results]  The results showed that unmated adult female moths were significantly attracted to crude extracts obtained using dichloromethane, ethyl acetate, and absolute ethyl alcohol. Among these, the crude extract derived from the ethyl acetate fraction demonstrated the most potent effect. Three terpene compounds, phytol, squalene and α-pinene, were identified in the crude extract. Field studies showed that phytol attracted moths at high concentrations (1×10^﹣2 mg·mL^﹣1), whereas squalene consistently repelled moths. [Conclusion]  This research identified three active terpene compounds in T. diversifolia and demonstrated the regulatory effect of phytol and squalene on diamondback moth behavior.