Biosynthesis of the sex pheromone components (Z)-5-dodecenol and (Z,E)-5,7-dodecadienol in Dendrolimus punctatus was studied by topical application of deuterium-labeled fatty acids to pheromone glands and subsequent analysis of fatty acyl groups and pheromone components by gas chromatography-mass spectrometry. Our studies suggest that both (Z)-5-dodecenol and (Z,E)-5,7-dodecadienol can be biosynthetically derived from chain elongation of palmitate to stearate in the gland, and its subsequent Delta11 desaturation to produce (Z)-11-octadecenoate. After three cycles of 2-carbon chain-shortening, the pheromone glands produce (Z)-5-dodecenoate, which is then converted to (Z)-5-dodecenol by reduction. A second Delta11 desaturation of (Z)-9-hexadecenoate produces (Z,E)-9,11-hexadecadienoate, which is then chain shortened in two cycles of beta-oxidation and finally converted to (Z,E)-5,7-dodecadienol by reduction.