We report identification of the sex attractant of the rosy Russian gypsy moth, Lymantria mathura Moore. Two compounds, Z,Z,Z-3,6,9-nonadecatriene 1 and its monoepoxide Z,Z-(9S,10R)-9,10-epoxy-3,6-nonadecadiene 4a, have been identified from abdominal tip ex tracts of female moths based on coupled gas chromatography/electroantennogram detector responses and dose response curves. Single cell recordings showed that only one of the mo noepoxide enantiomers (S,R) was active. In field tests, both the (S,R)-monoepoxide and the racemate were active. This type of pheromone system, unusual for a Lymantriid, is more typical of those found in the families Arctiidae, Noctuidae and Geometridae.