Porapak Q-captured volatiles from both sexes of Trypodendron betulae Swaine (Coleoptera: Curculionidae: Scolytinae) excised from newly attacked logs of paper birch, Betula papyrifera Marshall (Betulaceae), as well as volatiles from unattacked birch logs, were analysed by coupled gas chromatographic electroantennographic detection analysis. Active compounds were identified by gas chromatographic mass spectroscopy. The enantiomeric ratio of 6-ethenyl-2,2,6-trimethyloxan-3-ol (linalool oxide pyranoid) was determined using a Cyclodex B column. Field-trapping experiments disclosed that the female-produced aggregation pheromone of T. betulae is a blend of the (3S,6R)-trans- and (3R,6R)-cis-linalool oxide pyranoid. Trap catches were synergistically increased when the pheromone was combined with both the host volatile ethanol and with conophthorin, which was found in female beetles as well as host volatiles. Use of linalool oxide pyranoid reproductively isolates T. betulae from sympatric Trypodendron Stephens species for which only (+)-lineatin has been identified as an aggregation pheromone.