The sex attractant pheromone blend of Hemileuca maia (Lepidoptera: Saturniidae) from the vicinity of Baton Rouge, Louisiana, has been identified. The major component of the blend is (E10,Z12)-hexadeca-10,12-dienal (E10,Z12-16:Ald), in combination with the minor components (E10,Z12)-hexadeca-10,12-dien-1-ol (E10,Z 12-16:OH), and (E10,Z12)-hexadeca-10,12dien-1-yl acetate (E10,Z12-16:Ac). Ratios of the compounds in extracts of female pheromone glands varied around a mean of 100:7.4:6.3. None of the three components were attractive to male moths when tested as single components. Several other compounds were tentatively identified from female pheromone gland extracts, including E10,E12-16:Ald, E10,E12-16:OH, and E10,E12-16:Ac, but addition of these components, either alone or in combination, at biologically relevant rates, did not significantly increase the attractiveness of lures. The saturated analogs, hexadecanal, hexadecanol, and hexadecyl acetate, also were identified in gland extracts, but had no apparent effect as pheromone components.