<p>We describe the identification, synthesis, and field testing of an aggregation-sex pheromone produced by male <i>Acalolepta aesthetica</i> (Olliff 1890) (Coleoptera: Cerambycidae: Lamiinae), a cerambycid beetle native to Australia that has recently become established in Hawai‘i. Comparing extracts of headspace volatiles from both sexes revealed that males emitted two sex-specific volatiles, (3<i>E</i>,5<i>Z</i>)-octadien-2-ol and (3<i>E</i>,5<i>Z</i>)-octadien-2-one. Both compounds were synthesized and their bioactivity was tested in field bioassays. Only (3<i>E</i>,5<i>Z</i>)-octadien-2-ol was attractive to beetles of both sexes in these trials, and the corresponding ketone appeared to antagonize attraction when combined with the alcohol. In a dose-response study, traps baited with all doses of (3<i>E</i>,5<i>Z</i>)-octadien-2-ol except 33.3&#xa0;mg captured more beetles than solvent-control traps, with no significant differences among the effective doses. In a subsequent field trial, beetle capture did not differ between 100&#xa0;mg of a racemic blend and the insect-produced (<i>R</i>)<i>-</i>enantiomer of this compound, indicating that the unnatural (<i>S</i>)-enantiomer is not antagonistic. No other cerambycid species were captured during our field trials. The structural motif of (3<i>E</i>,5<i>Z</i>)-octadien-2-ol is unique among pheromones identified from lamiines to date. Together, our findings provide a foundation for developing pheromone-based tools to detect, delimit and potentially manage <i>A. aesthetica</i>.</p>