AbstractIn field studies conducted to improve trapping programs for the white pine cone beetle, Conophthorus coniperda (Schwarz), a twig beetle, Pityophthorus puberulus (LeConte), a common associate of eastern white pine, Pinus strobus L. (Pinaceae), in seed orchards, was also captured. In these experiments, P. puberulus was attracted to traps containing the sex pheromone pityol with or without the monoterpenes (−)-α-pinene and (−)-β-pinene, but attraction to traps was inhibited when S-(−)-limonene was present. We speculate that limonene may play an important role in host recognition and suitability, by indicating a resource suitable for C. coniperda but unsuitable for P. puberulus.