Bark beetles (Coleoptera: Scolytidae) are believed to use a combination of host kairomones and aggregation pheromones to locate suitable hosts. Rejection likely occurs in the absence of host cues or in the presence of non-host cues such as angiosperm bark volatiles (BV) or green leaf volatiles (GLV), which are collectively termed nonhost angiosperm volatiles (NAV). Several studies have shown that NAVs disrupt the positive chemotactic behavior of coniferophagous bark beetles. While the responses of a number of economically-important bark beetles to NAVs are well-documented, little is known about the response of the western pine beetle (WPB), Dendroctonus brevicomis, to these semiochemicals. We conducted a 30-replicate trapping bioassay at McCloud Flats, Shasta-Trinity National Forest in northern California (41.35 º N, 121.95 º W; 1150 m elevation) in June 2004. Treatments included: (1) a group of BVs consisting of benzaldehyde, benzyl alcohol, guaiacol, conophthorin, nonanal, and salicylaldehyde, (2) a group of GLVs consisting of (E)-2-hexenal, (E)-2-hexen-1-ol, and (Z)-2-hexen-1-ol, (3) the WPB antiaggregation pheromone, 84%-(–)-verbenone, alone, and (4) various combinations of BVs, GLVs, and verbenone. Preliminary results indicate that BVs, GLVs, and verbenone alone and in combination significantly reduced WPB attraction to baited traps. The ternary combination (BVs + GLVs + verbenone) reduced trap catch by 89.5%. Complete analysis and further experimentation to better characterize the response of WPB to NAVs are ongoing. The operational use of NAVs, with or without verbenone, may have merit for reducing WPB infestations in ponderosa pine stands.