The flight response of Dendroctonus valens LeConte to monoterpenes from host pines has been well studied, but little is known of the response to behavioral chemicals produced by beetles (i.e., pheromones). In 2006 and 2007, we conducted field studies of the flight response of D. valens to compounds produced by the beetles and related species. The choice of compounds to test in the field was guided by chemical analyses of volatiles from beetles, by electrophysiological analyses of the responses by the beetles to synthetic compounds and extracts, and by preliminary field screening of a larger set of combinations of potential behavioral chemicals. Small groups of JH III-treated or Pinus radiata-fed females produced the bicyclic acetal frontalin (20 to 140 ng/beetle over 46 hr); groups of males did not produce frontalin irrespective of treatment. Both sexes in this experiment also produced cis- and trans-verbenol and verbenone, with females producing more cis- and trans-verbenol and males generally producing more verbenone. GC-EAD analyses showed stereospecific antennal responses by both sexes to synthetic (-)-frontalin, and to synthetic (+)-seudenol, (+)-ipsdienol, (-)-verbenone, (+)-exo-, and (+)-endo-brevicomin, all frequently occurring Dendroctonus spp. pheromone compounds. In a field bioassay, male D. valens responded significantly to all release rates of frontalin (20 µg/d to 2.6 mg/d) when it was presented with host monoterpenes. The response of females to host monoterpenes was not affected by frontalin. We propose that frontalin is a female-produced sex pheromone component for D.valens.