Abstract We report the preparation of 1-tetrahydro-pyranyloxy dodec 11-yne (1), from castor oil, with an overall yield of 9.6%, and illustrate its use with the novel and practical synthesis of 1-oxo octadec (z) 11-ene (2), the insect sex pheromone of Achroia grisella, a species of wax moth, which are specific enemies of bees1. Parenthetically, it has been found that 1 is a good precursor to the surprisingly large number of pheromones that have the structural ...