The California fivespined ips, Ips paraconfusus Lanier, attacks various pines in California forests. Males produce a pheromone containing three synergistic monoterpene alcohols, (4S)-(-)-ipsenol, (4S)-(+)-ipsdienol, and (1S,2S)-(+)-cis-verbenol. The commercially available pheromone for I. paraconfusus contains the three alcohols with the most easily produced enantiomers, an equal (racemic) mixture of the optical isomers of ipsenol and ipsdienol, and ~80%-(1R,2R)-(-)-cis-verbenol. To begin refining the aggregation pheromone, we determined whether I. paraconfusus responded differently to various release rates and enantiomers of ipsdienol while keeping ipsenol and cis-verbenol components constant. Also, we tested whether conophthorin, known to interrupt flight of other bark beetles, would influence the flight response of I. paraconfusus. In 2004, funnel traps were baited with commercially available pheromones in Blodgett Research Forest. Treatments included: 1) an unbaited control; 2) racemic ipsdienol (1X), racemic ipsenol, 83%-(–)-cis-verbenol; 3) racemic ipsdienol (2X), ipsenol, cis-verbenol; 4) (S)-(+)-ipsdienol (1X), ipsenol, cis-verbenol; 5) (R)-(-)-ipsdienol (1X), ipsenol, cis-verbenol; 6) (S)-(+)-ipsdienol (1X), racemic conophthorin, ipsenol, cis-verbenol; and 7) racemic conophthorin. All seven treatments were replicated in four blocks with treatments re-randomized nine times. We captured the most I. paraconfusus in the trap containing (+)-ipsdienol. A doubled release rate of racemic ipsdienol attracted fewer beetles than the single release rate of (+)-ipsdienol; this indicates that the (-)-enantiomer of ipsdienol interrupts the attractive response. Conophthorin interrupted its response to (+)-ipsdienol. Among treatments tested, the most effective attractant was racemic ipsenol, (+)-ipsdienol, and (-)-cis-verbenol. Both (-)-ipsdienol and conophthorin could be used to interrupt the aggregation response of I. paraconfusus.