Collections of volatile chemicals emitted from flowers of night-blooming jessamine,Cestrum nocturnumL., yielded three principal chemicals; benzaldehyde, benzyl acetate, and phenylacetaldehyde. Female cabbage looper moths,Trichoplusia ni(Hübner), exhibited upwind oriented flight and contact with dispensers that released an artificial blend of synthetic compounds similar to the natural blend from jessamine flowers. Observed behaviors in response to phenylacetaldehyde alone were not Significantly different from those to the complete blend, although moths also oriented to benzyl acetate. Based on these results, phenylacetaldehyde alone may provide optimum attraction of cabbage looper moths to the flowers and to artificial lures. The plants displayed a diel periodicity in the release of these compounds coincident with the diel pattern of feeding activity of cabbage looper moths. Moth feeding occurs principally at and immediately after dusk, and the production of the floral odor peaked in the first 2 h of the scotophase.