(Z ,Z )-3,9-cis-6,7-Epoxyheptadecadiene, and (Z,Z)-6,9-cis -3,4-epoxyheptadecadiene were identified by gas chromatography/flame ionization detection-electroantennographic detection (GC/FID-EAD) and coupled gas chromatography-mass spectrometry (GC-MS) from abdominal tip extracts of Tephrina arenacearia (Lepidoptera: Geometridae), an alfalfa pest. In gas chromatography/flame ionization-single sensillum detection (GC/FID-SC) analyses, specific olfactory receptor cells were found for (Z,Z)-6,9-cis-3,4-epoxyheptadecadiene, and tricosane. Synthetic samples of racemic (Z,Z )-6,9-cis-3,4-epoxyheptadecadiene attracted large numbers of male T. arenacearia into traps. Best catches were observed at 100-1000 μg dosages. The addition of (Z,Z,Z)-3,6,9-heptadecatriene did not influence catches. (Z,Z,Z)-3,6,9-Heptadecatriene and (Z,Z)-6,9-cis-3,4-epoxyheptadecadiene were also identified in the pheromone gland extract of Chiasma clathrata, an other geometrid pest of alfalfa.