A ▵11-desaturase gene was cloned from the sex pheromone gland of the obliquebanded leafroller moth, Choristoneura rosaceana. The desaturase cDNA sequence spans 1300 nucleotides with an open reading frame encoding a 335 amino-acid protein, which has 81% identity to a Z/E11-desaturase of the redbanded leafroller moth, Argyrotaenia velutinana. A functional assay with a pYES2 yeast expression system demonstrated that the ▵11-desaturase exhibits unusual substrate and stereospecificities in producing a Z/E11 mixture (7:1) of only C14 acids. A metabolic Z9-desaturase also was cloned from fat body of this species, and proved to be in the class that produces more Z9-16:Acid than Z9-18:Acid.