Two sesquiterpene hydrocarbons, β-copaene and β-ylangene, were isolated from bioactive fractions of angelica seed oil and were shown by field bioassays to be attractive to the male Mediterranean fruit fly. Their relative attractiveness, compared with the(+)-and (-)-α-copaene enantiomers, are: (+)-α-copaene>angelica β-copaene>angelica β-ylangene>(-)-α-copaene. The enantiomer ratios for the two compounds are: β-copaene, 61.4% (+), 38.6% (-); β-ylangene, 91.9% (+), 8.1% (-).trans-α-Bergamotene was also isolated from the same fractions, but in sufficient quantity for bioassay [enantiomer ratio: 95.7% (+), 4.3% (-)].