Byers, J.A., Wood, D.L., Browne, L.E., Fish, R.H., Piatek, B., & Hendry, L.B. 1979. Relationship between a host plant compound, myrcene and pheromone production in the bark beetle, Ips paraconfusus. Journal of Insect Physiology 25:477-482.

Intestine of Ips paraconfusus male (female looks identical)
Abstract-- The pheromonal components, ipsenol and ipsdienol were found in increasing quantities in hindguts of only the male sex of I. paraconfusus following exposure of both sexes to a series of increasing concentrations of myrcene (from Pinus ponderosa) vapor. Hindguts of female and male beetles contained similar quantities of myrcene and other volatile compounds associated with myrcene exposure. Unexposed beetles of both sexes did not contain detectable amounts of any volatile compound. This indicates that myrcene induces or is a precursor for sex-specific pheromone biosynthesis.
entire paper
Chemical Ecology