Bark beetles are among the most economically important forest pests in the northern hemisphere and are responsible for the loss of billions of board feet of coniferous standing timber each year. Moreover, trees killed by these aggressive pests add significant fuel loading to the forest and kindle extreme fires that pose significant threat to property and life. These insects produce monoterpenoid aggregation pheromone components that coordinate host colonization and mating. The long term goal of this project is to develop effective pest management tactics targeting the chemically-mediated mating system of the beetles. In this study, we investigate the interplay between feeding on host phloem and the induction of de novo pheromone biosynthesis in Ips confusus, the pinyon Ips. I. confusus has become a major pest in the southwestern United States, destroying hundreds of thousands of acres of pinyon pines. We have found that feeding on host phloem strongly induces pheromone production in male I. confusus. Moreover, feeding, but not JH III treatment, stimulates the activity of a key mevalonate pathway enzyme, 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-R), only in males. However, feeding and JH III both significantly up-regulate mRNA levels of HMG-R and other mevalonate pathway genes. Our data suggest that JH III alone cannot stimulate pheromone biosynthesis in male I. confusus, and some other regulatory factor, perhaps a brain hormone, is required for pheromone production.