Bark beetles in the genus Ips produce and perceive blends of pheromone compounds. Ipsenol and ipsdienol are two pheromone and allomone components whose specificity may guide resource partitioning of the same host pine by sympatric species in different subgeneric groups. The stereochemistry of ipsdienol is particularly crucial to the aggregation behavior of I. pini. Because both males and females respond to male-produced blends of (-)-ipsdienol, the link between the stereospecificity of response and production can be tested directly by measuring the production of ipsdienol for each response group. In the sympatric species I. paraconfusus, the presence or absence of monoterpene precursors may delineate which hosts can be colonized. The analysis of extract samples using GC-MS instrumentation and field bioassays on the aggregation behavior of I. pini will improve understanding of Ips chemical ecology, a subject of great interest to foresters since bark beetles are serious forest pests.