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The male red pine sawflyNeodiprion nanulus nanulus Schedl responds mainly to the (2S,3S,7S)-3,7-dimethylpentadecan-2-yl acetate (2S,3S,7S-A) in the field. No other isomer is as effective by itself or syner-gizes 2S,3S, 7S-A in this species. ForNeodiprion sertifer (Geoffroy), however, we confirmed our earlier report that males responded significantly to a 5∶0.003 mixture of 2S,3S,7S-A and either 2S,3R,7R-A or 2S,3R,7R/S-A. The 2S,3S,7S-A isomer was separated from 2S,3R,7R-A by capillary gas-liquid chromatographic (GLC) analysis using Carbowax 20 M and DB-5 columns. The latter column also separated 2S,3S,7S-A from 2S,3R,7S-A. Only 2S,3S,7S-A was found in the natural pheromones ofN. n. nanulus andN. sertifer by GLC analysis.

The sex pheromones ofNeodiprion pinetum (Norton) andDiprion similis (Hartig) consist of two isomers, 2S,3S,7S and 2S,3R,7R, in either the acetate orpropionate forms of 3,7-dimethylpentadecan-2-ol, respectively. The 2S,3S,7S acetate isomer is utilized byN. pinetum as the major pheromone component and the 2S,3R,7R acetate as a Synergist. ConverselyD. similis utilizes 2S,3R,7R as propionate the major pheromone component and 2S,3S,7S propionate as a Synergist. This was confirmed in the field in both Michigan and Wisconsin. Capillary gas-liquid chromatographie analyses revealed that these two isomers are present in the natural pheromones of both species at the ratios close to those predicted by artificial blending of the two optical isomers.