Relative attraction of the black turpentine beetle (BTB),Dendroctonus terebrans(Olivier), to the monoterpene constituents of gum turpentine, a synthetic mixture of monoterpenes approximating the composition of turpentine, and whole gum turpentine was determined in the field by comparing each of the test substances as baits in standard BTB traps. Both individual monoterpenes and the monoterpene mixture were less attractive to BTB adults than whole gum turpentine. The preferential attraction of BTB adults to slash pine,Pinus elliottiiEngelm. var.elliottii, trees stressed by application of the herbicide paraquat to a bark wound was investigated and changes in the monoterpene compositions of the stressed trees were compared with BTB attack and landing rates. Paraquat-treated trees attracted significantly more BTB and received significantly more attacks than wounded or nontreated trees. Paraquat treatments resulted in small but significant changes in the oleoresin percentages of α-pinene and β-pinene. These changes could not be correlated with increased attraction of BTB to paraquat-treated trees, however.